[tarantool-patches] [PATCH v1 1/1] sql: replace sql column mask with core mask

Kirill Shcherbatov kshcherbatov at tarantool.org
Thu Aug 30 18:18:01 MSK 2018


Refactored SQL Bitmask with tarantool core uint64_t column mask
and API functions.

Closes #3571.
---
Branch: http://github.com/tarantool/tarantool/tree/kshch/gh-3571-replace-sql-column-mask
Issue: https://github.com/tarantool/tarantool/issues/3571

 src/box/column_mask.h   |   23 +-
 src/box/sql/delete.c    |    4 +-
 src/box/sql/expr.c      |   76 ++--
 src/box/sql/resolve.c   |   25 +-
 src/box/sql/sqliteInt.h |   69 ++--
 src/box/sql/update.c    |   10 +-
 src/box/sql/vdbeaux.c   |    2 +-
 src/box/sql/where.c     | 1051 ++++++++++++++++++++++++-----------------------
 src/box/sql/whereInt.h  |  149 +++++--
 src/box/sql/wherecode.c |  509 ++++++++++++-----------
 src/box/sql/whereexpr.c |  160 ++++----
 11 files changed, 1069 insertions(+), 1009 deletions(-)

diff --git a/src/box/column_mask.h b/src/box/column_mask.h
index d71911d..cf52913 100644
--- a/src/box/column_mask.h
+++ b/src/box/column_mask.h
@@ -50,7 +50,9 @@
  * in such case we set not one bit, but a range of bits.
  */
 
-#define COLUMN_MASK_FULL UINT64_MAX
+#define COLUMN_MASK_FULL	UINT64_MAX
+#define COLUMN_MASK_BIT(n)	(((uint64_t)1)<<(n))
+#define COLUMN_MASK_SIZE	((int)(sizeof(uint64_t)*8))
 
 /**
  * Set a bit in the bitmask corresponding to a
@@ -61,12 +63,12 @@
 static inline void
 column_mask_set_fieldno(uint64_t *column_mask, uint32_t fieldno)
 {
-	if (fieldno >= 63)
+	if (fieldno >= COLUMN_MASK_SIZE - 1)
 		/*
 		 * @sa column_mask key_def declaration for
 		 * details.
 		 */
-		*column_mask |= ((uint64_t) 1) << 63;
+		*column_mask |= ((uint64_t) 1) << (COLUMN_MASK_SIZE - 1);
 	else
 		*column_mask |= ((uint64_t) 1) << fieldno;
 }
@@ -80,7 +82,7 @@ column_mask_set_fieldno(uint64_t *column_mask, uint32_t fieldno)
 static inline void
 column_mask_set_range(uint64_t *column_mask, uint32_t first_fieldno_in_range)
 {
-	if (first_fieldno_in_range < 63) {
+	if (first_fieldno_in_range < COLUMN_MASK_SIZE - 1) {
 		/*
 		 * Set all bits by default via COLUMN_MASK_FULL
 		 * and then unset bits preceding the operation
@@ -90,11 +92,22 @@ column_mask_set_range(uint64_t *column_mask, uint32_t first_fieldno_in_range)
 		*column_mask |= COLUMN_MASK_FULL << first_fieldno_in_range;
 	} else {
 		/* A range outside "short" range. */
-		*column_mask |= ((uint64_t) 1) << 63;
+		*column_mask |= ((uint64_t) 1) << (COLUMN_MASK_SIZE - 1);
 	}
 }
 
 /**
+ * Test if overflow flag is set in mask.
+ * @param column_mask Mask to test.
+ * @retval true If mask overflowed, false otherwise.
+ */
+static inline bool
+column_mask_is_overflowed(uint64_t column_mask)
+{
+	return column_mask & (((uint64_t) 1) << (COLUMN_MASK_SIZE - 1));
+}
+
+/**
  * True if the update operation does not change the key.
  * @param key_mask Key mask.
  * @param update_mask Column mask of the update operation.
diff --git a/src/box/sql/delete.c b/src/box/sql/delete.c
index 93ada3a..d146201 100644
--- a/src/box/sql/delete.c
+++ b/src/box/sql/delete.c
@@ -501,10 +501,8 @@ sql_generate_row_delete(struct Parse *parse, struct Table *table,
 		 */
 		sqlite3VdbeAddOp2(v, OP_Copy, reg_pk, first_old_reg);
 		for (int i = 0; i < (int)table->def->field_count; i++) {
-			testcase(mask != 0xffffffff && iCol == 31);
-			testcase(mask != 0xffffffff && iCol == 32);
 			if (mask == 0xffffffff
-			    || (i <= 31 && (mask & MASKBIT32(i)) != 0)) {
+			    || (i <= 31 && (mask & COLUMN_MASK_BIT(i)) != 0)) {
 				sqlite3ExprCodeGetColumnOfTable(v, table->def,
 								cursor, i,
 								first_old_reg +
diff --git a/src/box/sql/expr.c b/src/box/sql/expr.c
index 50505b1..fd0b2b2 100644
--- a/src/box/sql/expr.c
+++ b/src/box/sql/expr.c
@@ -1539,7 +1539,7 @@ sqlite3SrcListDup(sqlite3 * db, SrcList * p, int flags)
 		    sqlite3SelectDup(db, pOldItem->pSelect, flags);
 		pNewItem->pOn = sqlite3ExprDup(db, pOldItem->pOn, flags);
 		pNewItem->pUsing = sqlite3IdListDup(db, pOldItem->pUsing);
-		pNewItem->colUsed = pOldItem->colUsed;
+		pNewItem->column_used_mask = pOldItem->column_used_mask;
 	}
 	return pNew;
 }
@@ -2402,20 +2402,18 @@ sqlite3FindInIndex(Parse * pParse,	/* Parsing context */
 			/* Search for an existing index that will work for this IN operator */
 			for (pIdx = pTab->pIndex; pIdx && eType == 0;
 			     pIdx = pIdx->pNext) {
-				Bitmask colUsed; /* Columns of the index used */
-				Bitmask mCol;	/* Mask for the current column */
 				uint32_t part_count =
 					pIdx->def->key_def->part_count;
 				struct key_part *parts =
 					pIdx->def->key_def->parts;
 				if ((int)part_count < nExpr)
 					continue;
-				/* Maximum nColumn is BMS-2, not BMS-1, so that we can compute
-				 * BITMASK(nExpr) without overflowing
+				/*
+				 * Maximum nColumn is COLUMN_MASK_SIZE-2, not
+				 * COLUMN_MASK_SIZE-1, so that we can compute
+				 * bitmasks without overflowing.
 				 */
-				testcase(part_count == BMS - 2);
-				testcase(part_count == BMS - 1);
-				if (part_count >= BMS - 1)
+				if (part_count >= COLUMN_MASK_SIZE - 1)
 					continue;
 				if (mustBeUnique &&
 				    ((int)part_count > nExpr ||
@@ -2427,8 +2425,8 @@ sqlite3FindInIndex(Parse * pParse,	/* Parsing context */
 					 */
 					continue;
 				}
-
-				colUsed = 0;	/* Columns of index used so far */
+				/* Columns of the index used mask. */
+				uint64_t col_used_mask = 0;
 				for (i = 0; i < nExpr; i++) {
 					Expr *pLhs = sqlite3VectorFieldSubexpr(pX->pLeft, i);
 					Expr *pRhs = pEList->a[i].pExpr;
@@ -2451,20 +2449,25 @@ sqlite3FindInIndex(Parse * pParse,	/* Parsing context */
 					}
 					if (j == nExpr)
 						break;
-					mCol = MASKBIT(j);
-					if (mCol & colUsed)
-						break;	/* Each column used only once */
-					colUsed |= mCol;
+					/* Each column used only once. */
+					if (COLUMN_MASK_BIT(j) & col_used_mask)
+						break;
+					column_mask_set_fieldno(&col_used_mask,
+								j);
 					if (aiMap)
 						aiMap[i] = pRhs->iColumn;
 					else if (pSingleIdxCol && nExpr == 1)
 						*pSingleIdxCol = pRhs->iColumn;
 					}
 
-				assert(i == nExpr
-				       || colUsed != (MASKBIT(nExpr) - 1));
-				if (colUsed == (MASKBIT(nExpr) - 1)) {
-					/* If we reach this point, that means the index pIdx is usable */
+				assert((COLUMN_MASK_BIT(nExpr) - 1) !=
+				       col_used_mask || i == nExpr);
+				if (col_used_mask ==
+				    (COLUMN_MASK_BIT(nExpr) - 1)) {
+					/*
+					 * If we reach this point, that means
+					 * the index pIdx is usable.
+					 */
 					int iAddr = sqlite3VdbeAddOp0(v, OP_Once);
 					VdbeCoverage(v);
 					sqlite3VdbeAddOp4(v, OP_Explain,
@@ -2486,18 +2489,12 @@ sqlite3FindInIndex(Parse * pParse,	/* Parsing context */
 
 					if (prRhsHasNull) {
 #ifdef SQLITE_ENABLE_COLUMN_USED_MASK
-							i64 mask =
-							    (1 << nExpr) - 1;
-							sqlite3VdbeAddOp4Dup8(v,
-									      OP_ColumnsUsed,
-									      iTab,
-									      0,
-									      0,
-									      (u8
-									       *)
-									      &
-									      mask,
-									      P4_INT64);
+						uint64_t mask = (1 << nExpr) - 1;
+						sqlite3VdbeAddOp4Dup8(v,
+								      OP_ColumnsUsed,
+								      iTab, 0, 0,
+								      (u8*)&mask,
+								      P4_INT64);
 #endif
 						*prRhsHasNull = ++pParse->nMem;
 						if (nExpr == 1) {
@@ -3943,7 +3940,6 @@ sqlite3ExprCodeTarget(Parse * pParse, Expr * pExpr, int target)
 			int nFarg;	/* Number of function arguments */
 			FuncDef *pDef;	/* The function definition object */
 			const char *zId;	/* The function name */
-			u32 constMask = 0;	/* Mask of function arguments that are constant */
 			int i;	/* Loop counter */
 			sqlite3 *db = pParse->db;	/* The database connection */
 			struct coll *coll = NULL;
@@ -4005,12 +4001,13 @@ sqlite3ExprCodeTarget(Parse * pParse, Expr * pExpr, int target)
 							     target);
 			}
 
+			/* Mask of function arguments that are constant. */
+			uint64_t farg_const_mask = 0;
 			for (i = 0; i < nFarg; i++) {
-				if (i < 32
-				    && sqlite3ExprIsConstant(pFarg->a[i].
-							     pExpr)) {
-					testcase(i == 31);
-					constMask |= MASKBIT32(i);
+				if (i < 32 &&
+				    sqlite3ExprIsConstant(pFarg->a[i].pExpr)) {
+					column_mask_set_fieldno(&farg_const_mask,
+								i);
 				}
 				if ((pDef->funcFlags & SQLITE_FUNC_NEEDCOLL) !=
 				    0 && coll == NULL) {
@@ -4022,7 +4019,7 @@ sqlite3ExprCodeTarget(Parse * pParse, Expr * pExpr, int target)
 				}
 			}
 			if (pFarg) {
-				if (constMask) {
+				if (farg_const_mask != 0) {
 					r1 = pParse->nMem + 1;
 					pParse->nMem += nFarg;
 				} else {
@@ -4070,12 +4067,11 @@ sqlite3ExprCodeTarget(Parse * pParse, Expr * pExpr, int target)
 				sqlite3VdbeAddOp4(v, OP_CollSeq, 0, 0, 0,
 						  (char *)coll, P4_COLLSEQ);
 			}
-			sqlite3VdbeAddOp4(v, OP_Function0, constMask, r1,
+			sqlite3VdbeAddOp4(v, OP_Function0, farg_const_mask, r1,
 					  target, (char *)pDef, P4_FUNCDEF);
 			sqlite3VdbeChangeP5(v, (u8) nFarg);
-			if (nFarg && constMask == 0) {
+			if (nFarg != 0 && farg_const_mask == 0)
 				sqlite3ReleaseTempRange(pParse, r1, nFarg);
-			}
 			return target;
 		}
 	case TK_EXISTS:
diff --git a/src/box/sql/resolve.c b/src/box/sql/resolve.c
index 9a2d6ff..134292a 100644
--- a/src/box/sql/resolve.c
+++ b/src/box/sql/resolve.c
@@ -437,20 +437,18 @@ lookupName(Parse * pParse,	/* The parsing context */
 		pTopNC->nErr++;
 	}
 
-	/* If a column from a table in pSrcList is referenced, then record
-	 * this fact in the pSrcList.a[].colUsed bitmask.  Column 0 causes
-	 * bit 0 to be set.  Column 1 sets bit 1.  And so forth.  If the
-	 * column number is greater than the number of bits in the bitmask
-	 * then set the high-order bit of the bitmask.
+	/*
+	 * If a column from a table in pSrcList is referenced,
+	 * then record this fact in pSrcList.a.column_used_mask
+	 * bitmask.  Column 0 causes bit 0 to be set. Column 1
+	 * sets bit 1.  And so forth.  If the column number is
+	 * greater than the number of bits in the bitmask then
+	 * set the high-order bit of the bitmask.
 	 */
 	if (pExpr->iColumn >= 0 && pMatch != 0) {
-		int n = pExpr->iColumn;
-		testcase(n == BMS - 1);
-		if (n >= BMS) {
-			n = BMS - 1;
-		}
 		assert(pMatch->iCursor == pExpr->iTable);
-		pMatch->colUsed |= ((Bitmask) 1) << n;
+		column_mask_set_fieldno(&pMatch->column_used_mask,
+					pExpr->iColumn);
 	}
 
 	/* Clean up and return
@@ -492,10 +490,7 @@ sqlite3CreateColumnExpr(sqlite3 * db, SrcList * pSrc, int iSrc, int iCol)
 		p->space_def = pItem->pTab->def;
 		p->iTable = pItem->iCursor;
 		p->iColumn = (ynVar) iCol;
-		testcase(iCol == BMS);
-		testcase(iCol == BMS - 1);
-		pItem->colUsed |=
-			((Bitmask) 1) << (iCol >= BMS ? BMS - 1 : iCol);
+		column_mask_set_fieldno(&pItem->column_used_mask, iCol);
 		ExprSetProperty(p, EP_Resolved);
 	}
 	return p;
diff --git a/src/box/sql/sqliteInt.h b/src/box/sql/sqliteInt.h
index 1d32c9a..6945121 100644
--- a/src/box/sql/sqliteInt.h
+++ b/src/box/sql/sqliteInt.h
@@ -67,6 +67,7 @@
 
 #include <stdbool.h>
 
+#include "box/column_mask.h"
 #include "box/field_def.h"
 #include "box/sql.h"
 #include "box/txn.h"
@@ -2296,49 +2297,28 @@ struct IdList {
 	int nId;		/* Number of identifiers on the list */
 };
 
-/*
- * The bitmask datatype defined below is used for various optimizations.
- *
- * Changing this from a 64-bit to a 32-bit type limits the number of
- * tables in a join to 32 instead of 64.  But it also reduces the size
- * of the library by 738 bytes on ix86.
- */
-#ifdef SQLITE_BITMASK_TYPE
-typedef SQLITE_BITMASK_TYPE Bitmask;
-#else
-typedef u64 Bitmask;
-#endif
-
-/*
- * The number of bits in a Bitmask.  "BMS" means "BitMask Size".
- */
-#define BMS  ((int)(sizeof(Bitmask)*8))
-
-/*
- * A bit in a Bitmask
- */
-#define MASKBIT(n)   (((Bitmask)1)<<(n))
-#define MASKBIT32(n) (((unsigned int)1)<<(n))
-#define ALLBITS      ((Bitmask)-1)
-
-/*
- * The following structure describes the FROM clause of a SELECT statement.
- * Each table or subquery in the FROM clause is a separate element of
- * the SrcList.a[] array.
- *
- * With the addition of multiple database support, the following structure
- * can also be used to describe a particular table such as the table that
- * is modified by an INSERT, DELETE, or UPDATE statement.  In standard SQL,
- * such a table must be a simple name: ID.  But in SQLite, the table can
- * now be identified by a database name, a dot, then the table name: ID.ID.
- *
- * The jointype starts out showing the join type between the current table
- * and the next table on the list.  The parser builds the list this way.
- * But sqlite3SrcListShiftJoinType() later shifts the jointypes so that each
- * jointype expresses the join between the table and the previous table.
- *
- * In the colUsed field, the high-order bit (bit 63) is set if the table
- * contains more than 63 columns and the 64-th or later column is used.
+/**
+ * The following structure describes the FROM clause of a SELECT
+ * statement. Each table or subquery in the FROM clause is a
+ * separate element of the SrcList.a[] array.
+ *
+ * With the addition of multiple database support, the following
+ * structure can also be used to describe a particular table such
+ * as the table that is modified by an INSERT, DELETE, or UPDATE
+ * statement.  In standard SQL,
+ * such a table must be a simple name: ID.  But in SQLite, the
+ * table can now be identified by a database name, a dot, then
+ * the table name: ID.ID.
+ *
+ * The jointype starts out showing the join type between the
+ * current table and the next table on the list.  The parser
+ * builds the list this way. But sqlite3SrcListShiftJoinType()
+ * later shifts the jointypes so that each jointype expresses the
+ * join between the table and the previous table.
+ *
+ * In the column_used_mask field, the high-order bit (bit 63) is
+ * set if thetable contains more than 63 columns and the 64-th or
+ * later column is used.
  */
 struct SrcList {
 	int nSrc;		/* Number of tables or subqueries in the FROM clause */
@@ -2365,7 +2345,8 @@ struct SrcList {
 		int iCursor;	/* The VDBE cursor number used to access this table */
 		Expr *pOn;	/* The ON clause of a join */
 		IdList *pUsing;	/* The USING clause of a join */
-		Bitmask colUsed;	/* Bit N (1<<N) set if column N of pTab is used */
+		/** Bit N (1<<N) set if column N of pTab is used. */
+		uint64_t column_used_mask;
 		union {
 			char *zIndexedBy;	/* Identifier from "INDEXED BY <zIndex>" clause */
 			ExprList *pFuncArg;	/* Arguments to table-valued-function */
diff --git a/src/box/sql/update.c b/src/box/sql/update.c
index 3e39688..4d9abdc 100644
--- a/src/box/sql/update.c
+++ b/src/box/sql/update.c
@@ -195,9 +195,9 @@ sqlite3Update(Parse * pParse,		/* The parser context */
 	}
 	/*
 	 * The SET expressions are not actually used inside the
-	 * WHERE loop. So reset the colUsed mask.
+	 * WHERE loop. So reset the column_used_mask mask.
 	 */
-	pTabList->a[0].colUsed = 0;
+	pTabList->a[0].column_used_mask = 0;
 
 	hasFK = fkey_is_required(pTab->def->id, aXRef);
 
@@ -325,13 +325,13 @@ sqlite3Update(Parse * pParse,		/* The parser context */
 	if (is_pk_modified || hasFK != 0 || trigger != NULL) {
 		struct space *space = space_by_id(pTab->def->id);
 		assert(space != NULL);
-		u32 oldmask = hasFK ? space->fkey_mask : 0;
+		uint64_t oldmask = hasFK != 0 ? space->fkey_mask : 0;
 		oldmask |= sql_trigger_colmask(pParse, trigger, pChanges, 0,
 					       TRIGGER_BEFORE | TRIGGER_AFTER,
 					       pTab, on_error);
 		for (i = 0; i < (int)def->field_count; i++) {
 			if (oldmask == 0xffffffff
-			    || (i < 32 && (oldmask & MASKBIT32(i)) != 0)
+			    || (i < 32 && (oldmask & COLUMN_MASK_BIT(i)) != 0)
 			    || table_column_is_in_pk(pTab, i)) {
 				testcase(oldmask != 0xffffffff && i == 31);
 				sqlite3ExprCodeGetColumnOfTable(v, def,
@@ -365,7 +365,7 @@ sqlite3Update(Parse * pParse,		/* The parser context */
 			sqlite3ExprCode(pParse, pChanges->a[j].pExpr,
 					regNew + i);
 		} else if (0 == (tmask & TRIGGER_BEFORE) || i > 31
-			   || (newmask & MASKBIT32(i))) {
+			   || (newmask & COLUMN_MASK_BIT(i))) {
 			/* This branch loads the value of a column that will not be changed
 			 * into a register. This is done if there are no BEFORE triggers, or
 			 * if there are one or more BEFORE triggers that use this value via
diff --git a/src/box/sql/vdbeaux.c b/src/box/sql/vdbeaux.c
index 3b0c90c..7569970 100644
--- a/src/box/sql/vdbeaux.c
+++ b/src/box/sql/vdbeaux.c
@@ -2713,7 +2713,7 @@ sqlite3VdbeDeleteAuxData(sqlite3 * db, AuxData ** pp, int iOp, int mask)
 		AuxData *pAux = *pp;
 		if ((iOp < 0)
 		    || (pAux->iOp == iOp
-			&& (pAux->iArg > 31 || !(mask & MASKBIT32(pAux->iArg))))
+			&& (pAux->iArg > 31 || !(mask & COLUMN_MASK_BIT(pAux->iArg))))
 		    ) {
 			testcase(pAux->iArg == 31);
 			if (pAux->xDelete) {
diff --git a/src/box/sql/where.c b/src/box/sql/where.c
index a4a1c45..850e2a7 100644
--- a/src/box/sql/where.c
+++ b/src/box/sql/where.c
@@ -166,62 +166,61 @@ whereOrMove(WhereOrSet * pDest, WhereOrSet * pSrc)
 	memcpy(pDest->a, pSrc->a, pDest->n * sizeof(pDest->a[0]));
 }
 
-/*
- * Try to insert a new prerequisite/cost entry into the WhereOrSet pSet.
- *
+/**
+ * Try to insert a new prerequisite/cost entry into the WhereOrSet @set.
  * The new entry might overwrite an existing entry, or it might be
  * appended, or it might be discarded.  Do whatever is the right thing
  * so that pSet keeps the N_OR_COST best entries seen so far.
+ *
+ * @param set The WhereOrSet to be updated.
+ * @param prereq_mask Prerequisites of the new entry.
+ * @param run_cost Run-cost of the new entry.
+ * @param outputs_cnt Number of outputs for the new entry.
+ * @retval 1 on new record has been inserted, 0 otherwise.
  */
 static int
-whereOrInsert(WhereOrSet * pSet,	/* The WhereOrSet to be updated */
-	      Bitmask prereq,	/* Prerequisites of the new entry */
-	      LogEst rRun,	/* Run-cost of the new entry */
-	      LogEst nOut)	/* Number of outputs for the new entry */
+sql_where_or_set_append(struct WhereOrSet *set, uint64_t prereq_mask,
+			LogEst run_cost, LogEst outputs_cnt)
 {
 	u16 i;
 	WhereOrCost *p;
-	for (i = pSet->n, p = pSet->a; i > 0; i--, p++) {
-		if (rRun <= p->rRun && (prereq & p->prereq) == prereq) {
+	for (i = set->n, p = set->a; i > 0; i--, p++) {
+		if (run_cost <= p->rRun &&
+		    (prereq_mask & p->prereq_mask) == prereq_mask)
 			goto whereOrInsert_done;
-		}
-		if (p->rRun <= rRun && (p->prereq & prereq) == p->prereq) {
+		if (p->rRun <= run_cost &&
+		    (p->prereq_mask & prereq_mask) == p->prereq_mask)
 			return 0;
-		}
 	}
-	if (pSet->n < N_OR_COST) {
-		p = &pSet->a[pSet->n++];
-		p->nOut = nOut;
+	if (set->n < N_OR_COST) {
+		p = &set->a[set->n++];
+		p->nOut = outputs_cnt;
 	} else {
-		p = pSet->a;
-		for (i = 1; i < pSet->n; i++) {
-			if (p->rRun > pSet->a[i].rRun)
-				p = pSet->a + i;
+		p = set->a;
+		for (i = 1; i < set->n; i++) {
+			if (p->rRun > set->a[i].rRun)
+				p = set->a + i;
 		}
-		if (p->rRun <= rRun)
+		if (p->rRun <= run_cost)
 			return 0;
 	}
  whereOrInsert_done:
-	p->prereq = prereq;
-	p->rRun = rRun;
-	if (p->nOut > nOut)
-		p->nOut = nOut;
+	p->prereq_mask = prereq_mask;
+	p->rRun = run_cost;
+	if (p->nOut > outputs_cnt)
+		p->nOut = outputs_cnt;
 	return 1;
 }
 
-/*
- * Return the bitmask for the given cursor number.  Return 0 if
- * iCursor is not in the set.
- */
-Bitmask
-sqlite3WhereGetMask(WhereMaskSet * pMaskSet, int iCursor)
+
+uint64_t
+sql_where_get_mask(struct WhereMaskSet *mask_set, int cursor)
 {
 	int i;
-	assert(pMaskSet->n <= (int)sizeof(Bitmask) * 8);
-	for (i = 0; i < pMaskSet->n; i++) {
-		if (pMaskSet->ix[i] == iCursor) {
-			return MASKBIT(i);
-		}
+	assert(mask_set->n <= COLUMN_MASK_SIZE);
+	for (i = 0; i < mask_set->n; i++) {
+		if (mask_set->ix[i] == cursor)
+			return COLUMN_MASK_BIT(i);
 	}
 	return 0;
 }
@@ -441,55 +440,24 @@ where_scan_init(struct WhereScan *scan, struct WhereClause *clause,
 	return whereScanNext(scan);
 }
 
-/*
- * Search for a term in the WHERE clause that is of the form "X <op> <expr>"
- * where X is a reference to the iColumn of table iCur or of index pIdx
- * if pIdx!=0 and <op> is one of the WO_xx operator codes specified by
- * the op parameter.  Return a pointer to the term.  Return 0 if not found.
- *
- * If pIdx!=0 then it must be one of the indexes of table iCur.
- * Search for terms matching the iColumn-th column of pIdx
- * rather than the iColumn-th column of table iCur.
- *
- * The term returned might by Y=<expr> if there is another constraint in
- * the WHERE clause that specifies that X=Y.  Any such constraints will be
- * identified by the WO_EQUIV bit in the pTerm->eOperator field.  The
- * aiCur[]/iaColumn[] arrays hold X and all its equivalents. There are 11
- * slots in aiCur[]/aiColumn[] so that means we can look for X plus up to 10
- * other equivalent values.  Hence a search for X will return <expr> if X=A1
- * and A1=A2 and A2=A3 and ... and A9=A10 and A10=<expr>.
- *
- * If there are multiple terms in the WHERE clause of the form "X <op> <expr>"
- * then try for the one with no dependencies on <expr> - in other words where
- * <expr> is a constant expression of some kind.  Only return entries of
- * the form "X <op> Y" where Y is a column in another table if no terms of
- * the form "X <op> <const-expr>" exist.   If no terms with a constant RHS
- * exist, try to return a term that does not use WO_EQUIV.
- */
-WhereTerm *
-sqlite3WhereFindTerm(WhereClause * pWC,	/* The WHERE clause to be searched */
-		     int iCur,		/* Cursor number of LHS */
-		     int iColumn,	/* Column number of LHS */
-		     Bitmask notReady,	/* RHS must not overlap with this mask */
-		     u32 op,		/* Mask of WO_xx values describing operator */
-		     Index * pIdx)	/* Must be compatible with this index, if not NULL */
+struct WhereTerm *
+sql_where_find_term(struct WhereClause *where, int cursor, int column,
+		    uint64_t is_not_ready, u32 op, struct Index *index)
 {
-	WhereTerm *pResult = 0;
-	WhereTerm *p;
-	WhereScan scan;
-
-	p = whereScanInit(&scan, pWC, iCur, iColumn, op, pIdx);
+	struct WhereScan scan;
+	struct WhereTerm *p =
+		whereScanInit(&scan, where, cursor, column, op, index);
+	struct WhereTerm *result = NULL;
 	op &= WO_EQ;
-	while (p) {
-		if ((p->prereqRight & notReady) == 0) {
-			if (p->prereqRight == 0 && (p->eOperator & op) != 0)
-				return p;
-			if (pResult == 0)
-				pResult = p;
-		}
-		p = whereScanNext(&scan);
+	for (; p != NULL; p = whereScanNext(&scan)) {
+		if ((p->prereq_right_mask & is_not_ready) != 0)
+			continue;
+		if (p->prereq_right_mask == 0 && (p->eOperator & op) != 0)
+			return p;
+		if (result == NULL)
+			result = p;
 	}
-	return pResult;
+	return result;
 }
 
 /**
@@ -511,7 +479,7 @@ sqlite3WhereFindTerm(WhereClause * pWC,	/* The WHERE clause to be searched */
  */
 static inline struct WhereTerm *
 where_clause_find_term(struct WhereClause *where_clause, int cursor, int column,
-		       Bitmask is_ready, u32 op, struct space_def *space_def,
+		       uint64_t is_ready, u32 op, struct space_def *space_def,
 		       struct key_def *key_def)
 {
 	struct WhereTerm *result = NULL;
@@ -520,8 +488,9 @@ where_clause_find_term(struct WhereClause *where_clause, int cursor, int column,
 					      column, op, space_def, key_def);
 	op &= WO_EQ;
 	while (p != NULL) {
-		if ((p->prereqRight & is_ready) == 0) {
-			if (p->prereqRight == 0 && (p->eOperator & op) != 0)
+		if ((p->prereq_right_mask & is_ready) == 0) {
+			if (p->prereq_right_mask == 0 &&
+			   (p->eOperator & op) != 0)
 				return p;
 			if (result == NULL)
 				result = p;
@@ -618,13 +587,14 @@ isDistinctRedundant(Parse * pParse,		/* Parsing context */
 			continue;
 		int col_count = pIdx->def->key_def->part_count;
 		for (i = 0; i < col_count; i++) {
-			if (0 ==
-			    sqlite3WhereFindTerm(pWC, iBase, i, ~(Bitmask) 0,
-						 WO_EQ, pIdx)) {
-				if (findIndexCol
-				    (pParse, pDistinct, iBase, pIdx, i) < 0)
+			if (sql_where_find_term(pWC, iBase, i,
+						COLUMN_MASK_FULL, WO_EQ,
+						pIdx) == NULL) {
+				if (findIndexCol(pParse, pDistinct, iBase,
+						 pIdx, i) < 0)
 					break;
-				uint32_t j = pIdx->def->key_def->parts[i].fieldno;
+				uint32_t j =
+					pIdx->def->key_def->parts[i].fieldno;
 				if (pIdx->pTable->def->fields[j].is_nullable)
 					break;
 			}
@@ -691,7 +661,7 @@ termCanDriveIndex(WhereTerm * pTerm,	/* WHERE clause term to check */
 		return 0;
 	if ((pTerm->eOperator & WO_EQ) == 0)
 		return 0;
-	if ((pTerm->prereqRight & notReady) != 0)
+	if ((pTerm->prereq_right_mask & notReady) != 0)
 		return 0;
 	if (pTerm->u.leftColumn < 0)
 		return 0;
@@ -1643,8 +1613,8 @@ whereTermPrint(WhereTerm * pTerm, int iTerm)
 		} else if ((pTerm->eOperator & WO_OR) != 0
 			   && pTerm->u.pOrInfo != 0) {
 			sqlite3_snprintf(sizeof(zLeft), zLeft,
-					 "indexable=0x%lld",
-					 pTerm->u.pOrInfo->indexable);
+					 "indexable_mask=0x%lld",
+					 pTerm->u.pOrInfo->indexable_mask);
 		} else {
 			sqlite3_snprintf(sizeof(zLeft), zLeft, "left=%d",
 					 pTerm->leftCursor);
@@ -1688,10 +1658,11 @@ whereLoopPrint(WhereLoop * p, WhereClause * pWC)
 	int nb = 1 + (pWInfo->pTabList->nSrc + 3) / 4;
 	struct SrcList_item *pItem = pWInfo->pTabList->a + p->iTab;
 	Table *pTab = pItem->pTab;
-	Bitmask mAll = (((Bitmask) 1) << (nb * 4)) - 1;
+	uint64_t all_mask = COLUMN_MASK_BIT(nb * 4) - 1;;
 #ifdef SQLITE_DEBUG
 	sqlite3DebugPrintf("%c%2d.%0*llx.%0*llx", p->cId,
-			   p->iTab, nb, p->maskSelf, nb, p->prereq & mAll);
+			   p->iTab, nb, p->self_mask, nb,
+			   p->prereq_mask & all_mask);
 	sqlite3DebugPrintf(" %12s",
 			   pItem->zAlias ? pItem->zAlias : pTab->def->name);
 #endif
@@ -1883,10 +1854,10 @@ whereLoopCheaperProperSubset(const WhereLoop * pX,	/* First WhereLoop to compare
 		if (j < 0)
 			return 0;	/* X not a subset of Y since term X[i] not used by Y */
 	}
-  	if ((pX->wsFlags & WHERE_IDX_ONLY) != 0 
-		&& (pY->wsFlags & WHERE_IDX_ONLY) == 0) {
-    	return 0;  /* Constraint (5) */
-  	}
+	/* Constraint (5). */
+	if ((pX->wsFlags & WHERE_IDX_ONLY) != 0 &&
+	    (pY->wsFlags & WHERE_IDX_ONLY) == 0)
+		return 0;
 
 	return 1;		/* All conditions meet */
 }
@@ -1972,9 +1943,11 @@ whereLoopFindLesser(WhereLoop ** ppPrev, const WhereLoop * pTemplate)
 		assert(p->rSetup == 0 || pTemplate->rSetup == 0
 		       || p->rSetup == pTemplate->rSetup);
 
-		/* whereLoopAddBtree() always generates and inserts the automatic index
-		 * case first.  Hence compatible candidate WhereLoops never have a larger
-		 * rSetup. Call this SETUP-INVARIANT
+		/*
+		 * sql_where_loop_add_btree() always generates
+		 * and inserts the automatic index case first.
+		 * Hence compatible candidate WhereLoops never
+		 * have a larger rSetup. Call this SETUP-INVARIANT.
 		 */
 		assert(p->rSetup >= pTemplate->rSetup);
 
@@ -1986,32 +1959,28 @@ whereLoopFindLesser(WhereLoop ** ppPrev, const WhereLoop * pTemplate)
 		    && (pTemplate->nSkip) == 0
 		    && (pTemplate->wsFlags & WHERE_INDEXED) != 0
 		    && (pTemplate->wsFlags & WHERE_COLUMN_EQ) != 0
-		    && (p->prereq & pTemplate->prereq) == pTemplate->prereq) {
+		    && (p->prereq_mask & pTemplate->prereq_mask) ==
+		       pTemplate->prereq_mask)
 			break;
-		}
 
 		/* If existing WhereLoop p is better than pTemplate, pTemplate can be
 		 * discarded.  WhereLoop p is better if:
 		 *   (1)  p has no more dependencies than pTemplate, and
 		 *   (2)  p has an equal or lower cost than pTemplate
 		 */
-		if ((p->prereq & pTemplate->prereq) == p->prereq	/* (1)  */
-		    && p->rSetup <= pTemplate->rSetup	/* (2a) */
-		    && p->rRun <= pTemplate->rRun	/* (2b) */
-		    && p->nOut <= pTemplate->nOut	/* (2c) */
-		    ) {
-			return 0;	/* Discard pTemplate */
-		}
+		if ((p->prereq_mask & pTemplate->prereq_mask) ==
+		     p->prereq_mask && p->rSetup <= pTemplate->rSetup &&
+		     p->rRun <= pTemplate->rRun	&& p->nOut <= pTemplate->nOut)
+			return 0;
 
 		/* If pTemplate is always better than p, then cause p to be overwritten
 		 * with pTemplate.  pTemplate is better than p if:
 		 *   (1)  pTemplate has no more dependences than p, and
 		 *   (2)  pTemplate has an equal or lower cost than p.
 		 */
-		if ((p->prereq & pTemplate->prereq) == pTemplate->prereq	/* (1)  */
-		    && p->rRun >= pTemplate->rRun	/* (2a) */
-		    && p->nOut >= pTemplate->nOut	/* (2b) */
-		    ) {
+		if ((p->prereq_mask & pTemplate->prereq_mask) ==
+		    pTemplate->prereq_mask && p->rRun >= pTemplate->rRun &&
+		    p->nOut >= pTemplate->nOut) {
 			assert(p->rSetup >= pTemplate->rSetup);	/* SETUP-INVARIANT above */
 			break;	/* Cause p to be overwritten by pTemplate */
 		}
@@ -2060,9 +2029,10 @@ whereLoopInsert(WhereLoopBuilder * pBuilder, WhereLoop * pTemplate)
 			u16 n = pBuilder->pOrSet->n;
 			int x =
 #endif
-			    whereOrInsert(pBuilder->pOrSet, pTemplate->prereq,
-					  pTemplate->rRun,
-					  pTemplate->nOut);
+				sql_where_or_set_append(pBuilder->pOrSet,
+							pTemplate->prereq_mask,
+							pTemplate->rRun,
+							pTemplate->nOut);
 #ifdef WHERETRACE_ENABLED		/* 0x8 */
 			if (sqlite3WhereTrace & 0x8) {
 				sqlite3DebugPrintf(x ? "   or-%d:  " :
@@ -2181,7 +2151,7 @@ whereLoopOutputAdjust(WhereClause * pWC,	/* The WHERE clause */
 		      LogEst nRow)		/* Number of rows in the entire table */
 {
 	WhereTerm *pTerm, *pX;
-	Bitmask notAllowed = ~(pLoop->prereq | pLoop->maskSelf);
+	uint64_t not_allowed_mask = ~(pLoop->prereq_mask | pLoop->self_mask);
 	int i, j, k;
 	LogEst iReduce = 0;	/* pLoop->nOut should not exceed nRow-iReduce */
 
@@ -2189,9 +2159,9 @@ whereLoopOutputAdjust(WhereClause * pWC,	/* The WHERE clause */
 	for (i = pWC->nTerm, pTerm = pWC->a; i > 0; i--, pTerm++) {
 		if ((pTerm->wtFlags & TERM_VIRTUAL) != 0)
 			break;
-		if ((pTerm->prereqAll & pLoop->maskSelf) == 0)
+		if ((pTerm->prereq_all_mask & pLoop->self_mask) == 0)
 			continue;
-		if ((pTerm->prereqAll & notAllowed) != 0)
+		if ((pTerm->prereq_all_mask & not_allowed_mask) != 0)
 			continue;
 		for (j = pLoop->nLTerm - 1; j >= 0; j--) {
 			pX = pLoop->aLTerm[j];
@@ -2326,7 +2296,6 @@ whereLoopAddBtreeIndex(WhereLoopBuilder * pBuilder,	/* The WhereLoop factory */
 	WhereTerm *pTerm;	/* A WhereTerm under consideration */
 	int opMask;		/* Valid operators for constraints */
 	WhereScan scan;		/* Iterator for WHERE terms */
-	Bitmask saved_prereq;	/* Original value of pNew->prereq */
 	u16 saved_nLTerm;	/* Original value of pNew->nLTerm */
 	u16 saved_nEq;		/* Original value of pNew->nEq */
 	u16 saved_nBtm;		/* Original value of pNew->nBtm */
@@ -2380,7 +2349,8 @@ whereLoopAddBtreeIndex(WhereLoopBuilder * pBuilder,	/* The WhereLoop factory */
 	saved_nSkip = pNew->nSkip;
 	saved_nLTerm = pNew->nLTerm;
 	saved_wsFlags = pNew->wsFlags;
-	saved_prereq = pNew->prereq;
+	/* Original value of pNew->prereq_mask. */
+	uint64_t saved_prereq = pNew->prereq_mask;
 	saved_nOut = pNew->nOut;
 	pTerm = whereScanInit(&scan, pBuilder->pWC, pSrc->iCursor, saved_nEq,
 			      opMask, pProbe);
@@ -2402,7 +2372,7 @@ whereLoopAddBtreeIndex(WhereLoopBuilder * pBuilder,	/* The WhereLoop factory */
 			 */
 			continue;
 		}
-		if (pTerm->prereqRight & pNew->maskSelf)
+		if (pTerm->prereq_right_mask & pNew->self_mask)
 			continue;
 
 		/* Do not allow the upper bound of a LIKE optimization range constraint
@@ -2430,8 +2400,8 @@ whereLoopAddBtreeIndex(WhereLoopBuilder * pBuilder,	/* The WhereLoop factory */
 		if (whereLoopResize(db, pNew, pNew->nLTerm + 1))
 			break;	/* OOM */
 		pNew->aLTerm[pNew->nLTerm++] = pTerm;
-		pNew->prereq =
-		    (saved_prereq | pTerm->prereqRight) & ~pNew->maskSelf;
+		pNew->prereq_mask =
+		    (saved_prereq | pTerm->prereq_right_mask) & ~pNew->self_mask;
 
 		assert(nInMul == 0
 		       || (pNew->wsFlags & WHERE_COLUMN_NULL) != 0
@@ -2648,7 +2618,7 @@ whereLoopAddBtreeIndex(WhereLoopBuilder * pBuilder,	/* The WhereLoop factory */
 		pNew->nOut = saved_nOut;
 		pBuilder->nRecValid = nRecValid;
 	}
-	pNew->prereq = saved_prereq;
+	pNew->prereq_mask = saved_prereq;
 	pNew->nEq = saved_nEq;
 	pNew->nBtm = saved_nBtm;
 	pNew->nTop = saved_nTop;
@@ -2756,74 +2726,86 @@ indexMightHelpWithOrderBy(WhereLoopBuilder * pBuilder,
 	return 0;
 }
 
-/*
- * Add all WhereLoop objects for a single table of the join where the table
- * is identified by pBuilder->pNew->iTab.
+/**
+ * Add all WhereLoop objects for a single table of the join where
+ * the table is identified by loop_builder->pNew->iTab.
  *
- * The costs (WhereLoop.rRun) of the b-tree loops added by this function
- * are calculated as follows:
+ * The costs (WhereLoop.rRun) of the b-tree loops added by this
+ * function are calculated as follows:
  * rRun = log2(cost) * 10
  *
- * For a full scan, assuming the table (or index) contains nRow rows:
+ * For a full scan, assuming the table (or index) contains nRow
+ * rows:
  *
- *     cost = nRow * 3.0                          // full-table scan
- *     cost = nRow * K -> 4.0 for Tarantool       // scan of covering index
- *     cost = nRow * (K+3.0) -> 4.0 for Tarantool // scan of non-covering index
+ *    full-table scan:
+ *    cost = nRow * 3.0
+ *    scan of covering index:
+ *    cost = nRow * K -> 4.0 for Tarantool
+ *    scan of non-covering index:
+ *    cost = nRow * (K+3.0) -> 4.0 for Tarantool
  *
- * This formula forces usage of pk for full-table scan for Tarantool
+ * This formula forces usage of pk for full-table scan for
+ * Tarantool.
  *
- * where K is a value between 1.1 and 3.0 set based on the relative
- * estimated average size of the index and table records.
+ * where K is a value between 1.1 and 3.0 set based on the
+ * relative estimated average size of the index and table records.
  *
- * For an index scan, where nVisit is the number of index rows visited
- * by the scan, and nSeek is the number of seek operations required on
- * the index b-tree:
+ * For an index scan, where nVisit is the number of index rows
+ * visited by the scan, and nSeek is the number of seek operations
+ * required on the index b-tree:
  *
- *     cost = nSeek * (log(nRow) + K * nVisit)          // covering index
- *     cost = nSeek * (log(nRow) + (K+3.0) * nVisit)    // non-covering index
+ *    covering index:
+ *    cost = nSeek * (log(nRow) + K * nVisit)
+ *    non-covering index:
+ *    cost = nSeek * (log(nRow) + (K+3.0) * nVisit)
  *
- * Normally, nSeek is 1. nSeek values greater than 1 come about if the
- * WHERE clause includes "x IN (....)" terms used in place of "x=?". Or when
- * implicit "x IN (SELECT x FROM tbl)" terms are added for skip-scans.
+ * Normally, nSeek is 1. nSeek values greater than 1 come about
+ * if the WHERE clause includes "x IN (....)" terms used in place
+ * of "x=?". Or when implicit "x IN (SELECT x FROM tbl)" terms are
+ * added for skip-scans.
  *
- * The estimated values (nRow, nVisit, nSeek) often contain a large amount
- * of uncertainty.  For this reason, scoring is designed to pick plans that
- * "do the least harm" if the estimates are inaccurate.  For example, a
- * log(nRow) factor is omitted from a non-covering index scan in order to
- * bias the scoring in favor of using an index, since the worst-case
- * performance of using an index is far better than the worst-case performance
- * of a full table scan.
+ * The estimated values (nRow, nVisit, nSeek) often contain a
+ * large amount of uncertainty.  For this reason, scoring is
+ * designed to pick plans that "do the least harm" if the
+ * estimates are inaccurate.  For example, a log(nRow) factor is
+ * omitted from a non-covering index scan in order to bias the
+ * scoring in favor of using an index, since the worst-case
+ * performance of using an index is far better than the worst-case
+ * performance of a full table scan.
+ *
+ * @param loop_builder WHERE clause information.
+ * @param prereq_mask Extra prerequesites for using this table.
+ * @retval 0 On success, not 0 elsewhere.
  */
 static int
-whereLoopAddBtree(WhereLoopBuilder * pBuilder,	/* WHERE clause information */
-		  Bitmask mPrereq)		/* Extra prerequesites for using this table */
+sql_where_loop_add_btree(struct WhereLoopBuilder *loop_builder,
+			 uint64_t prereq_mask)
 {
-	WhereInfo *pWInfo;	/* WHERE analysis context */
-	Index *pProbe;		/* An index we are evaluating */
 	Index fake_index;		/* A fake index object for the primary key */
-	SrcList *pTabList;	/* The FROM clause */
-	struct SrcList_item *pSrc;	/* The FROM clause btree term to add */
-	WhereLoop *pNew;	/* Template WhereLoop object */
 	int rc = SQLITE_OK;	/* Return code */
 	int iSortIdx = 1;	/* Index number */
-	int b;			/* A boolean value */
 	LogEst rSize;		/* number of rows in the table */
-	WhereClause *pWC;	/* The parsed WHERE clause */
-	Table *pTab;		/* Table being queried */
 
-	pNew = pBuilder->pNew;
-	pWInfo = pBuilder->pWInfo;
-	pTabList = pWInfo->pTabList;
-	pSrc = pTabList->a + pNew->iTab;
-	pTab = pSrc->pTab;
-	pWC = pBuilder->pWC;
-
-	if (pSrc->pIBIndex) {
-		/* An INDEXED BY clause specifies a particular index to use */
-		pProbe = pSrc->pIBIndex;
+	/* Template WhereLoop object. */
+	struct WhereLoop *new_where_loop = loop_builder->pNew;
+	/* WHERE analysis context. */
+	struct WhereInfo *where_info = loop_builder->pWInfo;
+	/* The FROM clause. */
+	struct SrcList *tab_list = where_info->pTabList;
+	/* The FROM clause btree term to add. */
+	struct SrcList_item *src_list_table = tab_list->a + new_where_loop->iTab;
+	/* Table being queried. */
+	struct Table *table = src_list_table->pTab;
+	/* The parsed WHERE clause. */
+	struct WhereClause *where_clause = loop_builder->pWC;
+	/* An index we are evaluating. */
+	struct Index *index;
+	if (src_list_table->pIBIndex) {
+		/* An INDEXED BY clause specifies a particular index to use. */
+		index = src_list_table->pIBIndex;
 		fake_index.def = NULL;
-	} else if (pTab->pIndex) {
-		pProbe = pTab->pIndex;
+	} else if (table->pIndex) {
+		index = table->pIndex;
 		fake_index.def = NULL;
 	} else {
 		/* There is no INDEXED BY clause.  Create a fake Index object in local
@@ -2833,16 +2815,16 @@ whereLoopAddBtree(WhereLoopBuilder * pBuilder,	/* WHERE clause information */
 		 */
 		Index *pFirst;	/* First of real indices on the table */
 		memset(&fake_index, 0, sizeof(Index));
-		fake_index.pTable = pTab;
+		fake_index.pTable = table;
 
 		struct key_def *key_def = key_def_new(1);
 		if (key_def == NULL) {
-			pWInfo->pParse->nErr++;
-			pWInfo->pParse->rc = SQL_TARANTOOL_ERROR;
+			where_info->pParse->nErr++;
+			where_info->pParse->rc = SQL_TARANTOOL_ERROR;
 			return SQL_TARANTOOL_ERROR;
 		}
 
-		key_def_set_part(key_def, 0, 0, pTab->def->fields[0].type,
+		key_def_set_part(key_def, 0, 0, table->def->fields[0].type,
 				 ON_CONFLICT_ACTION_ABORT,
 				 NULL, COLL_NONE, SORT_ORDER_ASC);
 
@@ -2850,7 +2832,7 @@ whereLoopAddBtree(WhereLoopBuilder * pBuilder,	/* WHERE clause information */
 		index_opts_create(&opts);
 		opts.sql = "fake_autoindex";
 		fake_index.def =
-			index_def_new(pTab->def->id, 0,"fake_autoindex",
+			index_def_new(table->def->id, 0,"fake_autoindex",
 					sizeof("fake_autoindex") - 1,
 					TREE, &opts, key_def, NULL);
 		key_def_delete(key_def);
@@ -2858,8 +2840,8 @@ whereLoopAddBtree(WhereLoopBuilder * pBuilder,	/* WHERE clause information */
 		fake_index.def->iid = UINT32_MAX;
 
 		if (fake_index.def == NULL) {
-			pWInfo->pParse->nErr++;
-			pWInfo->pParse->rc = SQL_TARANTOOL_ERROR;
+			where_info->pParse->nErr++;
+			where_info->pParse->rc = SQL_TARANTOOL_ERROR;
 			return SQL_TARANTOOL_ERROR;
 		}
 
@@ -2867,18 +2849,18 @@ whereLoopAddBtree(WhereLoopBuilder * pBuilder,	/* WHERE clause information */
 			(struct index_stat *) malloc(sizeof(struct index_stat));
 		stat->tuple_log_est =
 			(log_est_t *) malloc(sizeof(log_est_t) * 2);
-		stat->tuple_log_est[0] = sql_space_tuple_log_count(pTab);
+		stat->tuple_log_est[0] = sql_space_tuple_log_count(table);
 		stat->tuple_log_est[1] = 0;
 		fake_index.def->opts.stat = stat;
 
-		pFirst = pSrc->pTab->pIndex;
-		if (pSrc->fg.notIndexed == 0) {
+		pFirst = src_list_table->pTab->pIndex;
+		if (src_list_table->fg.notIndexed == 0) {
 			/* The real indices of the table are only considered if the
 			 * NOT INDEXED qualifier is omitted from the FROM clause
 			 */
 			fake_index.pNext = pFirst;
 		}
-		pProbe = &fake_index;
+		index = &fake_index;
 	}
 
 #ifndef SQLITE_OMIT_AUTOMATIC_INDEX
@@ -2939,39 +2921,42 @@ whereLoopAddBtree(WhereLoopBuilder * pBuilder,	/* WHERE clause information */
 
 	/* Loop over all indices
 	 */
-	for (; rc == SQLITE_OK && pProbe; pProbe = pProbe->pNext, iSortIdx++) {
-		rSize = index_field_tuple_est(pProbe, 0);
-		pNew->nEq = 0;
-		pNew->nBtm = 0;
-		pNew->nTop = 0;
-		pNew->nSkip = 0;
-		pNew->nLTerm = 0;
-		pNew->iSortIdx = 0;
-		pNew->rSetup = 0;
-		pNew->prereq = mPrereq;
-		pNew->nOut = rSize;
-		pNew->pIndex = pProbe;
-		b = indexMightHelpWithOrderBy(pBuilder, pProbe, pSrc->iCursor);
+	for (; rc == SQLITE_OK && index != NULL;
+	     index = index->pNext, iSortIdx++) {
+		rSize = index_field_tuple_est(index, 0);
+		new_where_loop->nEq = 0;
+		new_where_loop->nBtm = 0;
+		new_where_loop->nTop = 0;
+		new_where_loop->nSkip = 0;
+		new_where_loop->nLTerm = 0;
+		new_where_loop->iSortIdx = 0;
+		new_where_loop->rSetup = 0;
+		new_where_loop->prereq_mask = prereq_mask;
+		new_where_loop->nOut = rSize;
+		new_where_loop->pIndex = index;
+		int b = indexMightHelpWithOrderBy(loop_builder, index,
+						  src_list_table->iCursor);
 		/* The ONEPASS_DESIRED flags never occurs together with ORDER BY */
-		assert((pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED) == 0
-		       || b == 0);
-		if (pProbe->def->iid == UINT32_MAX) {
+		assert((where_info->wctrlFlags & WHERE_ONEPASS_DESIRED) == 0 ||
+			b == 0);
+		if (index->def->iid == UINT32_MAX) {
 			/* Integer primary key index */
-			pNew->wsFlags = WHERE_IPK;
+			new_where_loop->wsFlags = WHERE_IPK;
 
 			/* Full table scan */
-			pNew->iSortIdx = b ? iSortIdx : 0;
+			new_where_loop->iSortIdx = b != 0 ? iSortIdx : 0;
 			/* TUNING: Cost of full table scan is (N*3.0). */
-			pNew->rRun = rSize + 16;
-			whereLoopOutputAdjust(pWC, pNew, rSize);
-			rc = whereLoopInsert(pBuilder, pNew);
-			pNew->nOut = rSize;
+			new_where_loop->rRun = rSize + 16;
+			whereLoopOutputAdjust(where_clause, new_where_loop,
+					      rSize);
+			rc = whereLoopInsert(loop_builder, new_where_loop);
+			new_where_loop->nOut = rSize;
 			if (rc)
 				break;
 		} else {
-			pNew->wsFlags = WHERE_IDX_ONLY | WHERE_INDEXED;
+			new_where_loop->wsFlags = WHERE_IDX_ONLY | WHERE_INDEXED;
 			/* Full scan via index */
-			pNew->iSortIdx = b ? iSortIdx : 0;
+			new_where_loop->iSortIdx = b != 0 ? iSortIdx : 0;
 
 			/* The cost of visiting the index rows is N*K, where K is
 			 * between 1.1 and 3.0 (3.0 and 4.0 for tarantool),
@@ -2982,24 +2967,27 @@ whereLoopAddBtree(WhereLoopBuilder * pBuilder,	/* WHERE clause information */
 			 * of secondary indexes, because secondary indexes
 			 * are not really store any data (only pointers to tuples).
 			 */
-			int notPkPenalty = sql_index_is_primary(pProbe) ? 0 : 4;
-			pNew->rRun = rSize + 16 + notPkPenalty;
-			whereLoopOutputAdjust(pWC, pNew, rSize);
-			rc = whereLoopInsert(pBuilder, pNew);
-			pNew->nOut = rSize;
+			int not_pk_penalty =
+				sql_index_is_primary(index) ? 0 : 4;
+			new_where_loop->rRun = rSize + 16 + not_pk_penalty;
+			whereLoopOutputAdjust(where_clause, new_where_loop,
+					      rSize);
+			rc = whereLoopInsert(loop_builder, new_where_loop);
+			new_where_loop->nOut = rSize;
 			if (rc)
 				break;
 		}
 
-		rc = whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, 0);
-		sqlite3Stat4ProbeFree(pBuilder->pRec);
-		pBuilder->nRecValid = 0;
-		pBuilder->pRec = 0;
+		rc = whereLoopAddBtreeIndex(loop_builder, src_list_table,
+					    index, 0);
+		sqlite3Stat4ProbeFree(loop_builder->pRec);
+		loop_builder->nRecValid = 0;
+		loop_builder->pRec = 0;
 
 		/* If there was an INDEXED BY clause, then only that one index is
 		 * considered.
 		 */
-		if (pSrc->pIBIndex)
+		if (src_list_table->pIBIndex != NULL)
 			break;
 	}
 	if (fake_index.def != NULL)
@@ -3010,132 +2998,150 @@ whereLoopAddBtree(WhereLoopBuilder * pBuilder,	/* WHERE clause information */
 	return rc;
 }
 
-/*
+/**
  * Add WhereLoop entries to handle OR terms.
+ * @param loop_builder WHERE clause information.
+ * @param prereq_mask Extra prerequesites for using this table.
+ * @retval 0 On success, not 0 elsewhere.
  */
 static int
-whereLoopAddOr(WhereLoopBuilder * pBuilder, Bitmask mPrereq, Bitmask mUnusable)
+sql_where_loop_add_or(struct WhereLoopBuilder *loop_builder,
+		      uint64_t prereq_mask)
 {
-	WhereInfo *pWInfo = pBuilder->pWInfo;
-	WhereClause *pWC;
-	WhereLoop *pNew;
-	WhereTerm *pTerm, *pWCEnd;
 	int rc = SQLITE_OK;
-	int iCur;
-	WhereClause tempWC;
-	WhereLoopBuilder sSubBuild;
-	WhereOrSet sSum, sCur;
-	struct SrcList_item *pItem;
-
-	pWC = pBuilder->pWC;
-	pWCEnd = pWC->a + pWC->nTerm;
-	pNew = pBuilder->pNew;
-	memset(&sSum, 0, sizeof(sSum));
-	pItem = pWInfo->pTabList->a + pNew->iTab;
-	iCur = pItem->iCursor;
-
-	for (pTerm = pWC->a; pTerm < pWCEnd && rc == SQLITE_OK; pTerm++) {
-		if ((pTerm->eOperator & WO_OR) != 0
-		    && (pTerm->u.pOrInfo->indexable & pNew->maskSelf) != 0) {
-			WhereClause *const pOrWC = &pTerm->u.pOrInfo->wc;
-			WhereTerm *const pOrWCEnd = &pOrWC->a[pOrWC->nTerm];
-			WhereTerm *pOrTerm;
-			int once = 1;
-			int i, j;
-
-			sSubBuild = *pBuilder;
-			sSubBuild.pOrderBy = 0;
-			sSubBuild.pOrSet = &sCur;
+	struct WhereClause *where_clause = loop_builder->pWC;
+	struct WhereLoop *where_loop = loop_builder->pNew;
+	struct WhereOrSet where_costs_set;
+	memset(&where_costs_set, 0, sizeof(where_costs_set));
+	struct WhereInfo *where_info = loop_builder->pWInfo;
+	struct SrcList_item *src_list_table =
+		where_info->pTabList->a + where_loop->iTab;
+	int cursor = src_list_table->iCursor;
+	struct WhereTerm *where_term = where_clause->a;
+	struct WhereTerm *where_term_end =
+		where_clause->a + where_clause->nTerm;
+	for (; where_term < where_term_end && rc == SQLITE_OK; where_term++) {
+		if ((where_term->eOperator & WO_OR) == 0
+		    || (where_term->u.pOrInfo->indexable_mask &
+			where_loop->self_mask) == 0)
+			continue;
 
-			WHERETRACE(0x200,
-				   ("Begin processing OR-clause %p\n", pTerm));
-			for (pOrTerm = pOrWC->a; pOrTerm < pOrWCEnd; pOrTerm++) {
-				if ((pOrTerm->eOperator & WO_AND) != 0) {
-					sSubBuild.pWC =
-					    &pOrTerm->u.pAndInfo->wc;
-				} else if (pOrTerm->leftCursor == iCur) {
-					tempWC.pWInfo = pWC->pWInfo;
-					tempWC.pOuter = pWC;
-					tempWC.op = TK_AND;
-					tempWC.nTerm = 1;
-					tempWC.a = pOrTerm;
-					sSubBuild.pWC = &tempWC;
-				} else {
-					continue;
-				}
-				sCur.n = 0;
+		WHERETRACE(0x200,
+			   ("Begin processing OR-clause %p\n", where_term));
+		int once = 1;
+		struct WhereLoopBuilder sub_loop_builder;
+		sub_loop_builder = *loop_builder;
+		sub_loop_builder.pOrderBy = 0;
+		struct WhereOrSet where_or_set;
+		sub_loop_builder.pOrSet = &where_or_set;
+		struct WhereClause temp_wc;
+
+		struct WhereClause *const or_wc = &where_term->u.pOrInfo->wc;
+		struct WhereTerm *or_term = or_wc->a;
+		struct WhereTerm *const or_term_end = &or_wc->a[or_wc->nTerm];
+		for (; or_term < or_term_end; or_term++) {
+			if ((or_term->eOperator & WO_AND) != 0) {
+				sub_loop_builder.pWC =
+				    &or_term->u.pAndInfo->wc;
+			} else if (or_term->leftCursor == cursor) {
+				temp_wc.pWInfo = where_clause->pWInfo;
+				temp_wc.pOuter = where_clause;
+				temp_wc.op = TK_AND;
+				temp_wc.nTerm = 1;
+				temp_wc.a = or_term;
+				sub_loop_builder.pWC = &temp_wc;
+			} else {
+				continue;
+			}
+			where_or_set.n = 0;
 #ifdef WHERETRACE_ENABLED
-				WHERETRACE(0x200,
-					   ("OR-term %d of %p has %d subterms:\n",
-					    (int)(pOrTerm - pOrWC->a), pTerm,
-					    sSubBuild.pWC->nTerm));
-				if (sqlite3WhereTrace & 0x400) {
-					sqlite3WhereClausePrint(sSubBuild.pWC);
-				}
+			WHERETRACE(0x200,
+				   ("OR-term %d of %p has %d subterms:\n",
+				    (int)(or_term - or_wc->a), where_term,
+				    sub_loop_builder.pWC->nTerm));
+			if (sqlite3WhereTrace & 0x400) {
+				sqlite3WhereClausePrint(sub_loop_builder.
+							pWC);
+			}
 #endif
-				{
-					rc = whereLoopAddBtree(&sSubBuild,
-							       mPrereq);
-				}
-				if (rc == SQLITE_OK) {
-					rc = whereLoopAddOr(&sSubBuild, mPrereq,
-							    mUnusable);
-				}
-				assert(rc == SQLITE_OK || sCur.n == 0);
-				if (sCur.n == 0) {
-					sSum.n = 0;
-					break;
-				} else if (once) {
-					whereOrMove(&sSum, &sCur);
-					once = 0;
-				} else {
-					WhereOrSet sPrev;
-					whereOrMove(&sPrev, &sSum);
-					sSum.n = 0;
-					for (i = 0; i < sPrev.n; i++) {
-						for (j = 0; j < sCur.n; j++) {
-							whereOrInsert(&sSum,
-								      sPrev.a[i].prereq
-								      | sCur.a[j].prereq,
-								      sqlite3LogEstAdd(sPrev.a[i].rRun,
-										       sCur.a[j].rRun),
-								      sqlite3LogEstAdd(sPrev.a[i].nOut,
-										       sCur.a[j].nOut));
-						}
+			rc = sql_where_loop_add_btree(&sub_loop_builder,
+						      prereq_mask);
+			if (rc == SQLITE_OK) {
+				rc = sql_where_loop_add_or(&sub_loop_builder,
+							   prereq_mask);
+			}
+			assert(rc == SQLITE_OK || where_or_set.n == 0);
+			if (where_or_set.n == 0) {
+				where_costs_set.n = 0;
+				break;
+			} else if (once) {
+				whereOrMove(&where_costs_set,
+					    &where_or_set);
+				once = 0;
+			} else {
+				struct WhereOrSet prev_costs_set;
+				whereOrMove(&prev_costs_set, &where_costs_set);
+				where_costs_set.n = 0;
+				for (int i = 0; i < prev_costs_set.n; i++) {
+					for (int j = 0; j < where_or_set.n;
+					     j++) {
+						uint64_t prereq =
+							prev_costs_set.a[i].
+							prereq_mask |
+							where_or_set.a[j].
+							prereq_mask;
+						LogEst run_cost =
+							sqlite3LogEstAdd(prev_costs_set.a[i].rRun,
+									 where_or_set.a[j].rRun);
+						LogEst outputs_cnt =
+							sqlite3LogEstAdd(prev_costs_set.a[i].nOut,
+									 where_or_set.a[j].nOut);
+						sql_where_or_set_append(&where_costs_set,
+									prereq,
+									run_cost,
+									outputs_cnt);
 					}
 				}
 			}
-			pNew->nLTerm = 1;
-			pNew->aLTerm[0] = pTerm;
-			pNew->wsFlags = WHERE_MULTI_OR;
-			pNew->rSetup = 0;
-			pNew->iSortIdx = 0;
-			pNew->nEq = 0;
-			pNew->nBtm = 0;
-			pNew->nTop = 0;
-			pNew->pIndex = NULL;
-			for (i = 0; rc == SQLITE_OK && i < sSum.n; i++) {
-				/* TUNING: Currently sSum.a[i].rRun is set to the sum of the costs
-				 * of all sub-scans required by the OR-scan. However, due to rounding
-				 * errors, it may be that the cost of the OR-scan is equal to its
-				 * most expensive sub-scan. Add the smallest possible penalty
-				 * (equivalent to multiplying the cost by 1.07) to ensure that
-				 * this does not happen. Otherwise, for WHERE clauses such as the
-				 * following where there is an index on "y":
-				 *
-				 *     WHERE likelihood(x=?, 0.99) OR y=?
-				 *
-				 * the planner may elect to "OR" together a full-table scan and an
-				 * index lookup. And other similarly odd results.
-				 */
-				pNew->rRun = sSum.a[i].rRun + 1;
-				pNew->nOut = sSum.a[i].nOut;
-				pNew->prereq = sSum.a[i].prereq;
-				rc = whereLoopInsert(pBuilder, pNew);
-			}
-			WHERETRACE(0x200,
-				   ("End processing OR-clause %p\n", pTerm));
 		}
+		where_loop->nLTerm = 1;
+		where_loop->aLTerm[0] = where_term;
+		where_loop->wsFlags = WHERE_MULTI_OR;
+		where_loop->rSetup = 0;
+		where_loop->iSortIdx = 0;
+		where_loop->nEq = 0;
+		where_loop->nBtm = 0;
+		where_loop->nTop = 0;
+		where_loop->pIndex = NULL;
+		for (int i = 0; rc == SQLITE_OK && i < where_costs_set.n; i++) {
+			/*
+			 * TUNING:
+			 * Currently where_costs_set.a[i].rRun
+			 * is where_or_set to the sum of the costs
+			 * of all sub-scans required by the
+			 * OR-scan. However, due to rounding
+			 * errors, it may be that the cost of the
+			 * OR-scan is equal to its most expensive
+			 * sub-scan. Add the smallest possible
+			 * penalty (equivalent to multiplying the
+			 * cost by 1.07) to ensure that this does
+			 * not happen. Otherwise, for WHERE
+			 * clauses such as the following where
+			 * there is an index on "y":
+			 *
+			 *     WHERE likelihood(x=?, 0.99) OR y=?
+			 *
+			 * the planner may elect to "OR" together
+			 * a full-table scan and an index lookup.
+			 * And other similarly odd results.
+			 */
+			where_loop->rRun = where_costs_set.a[i].rRun + 1;
+			where_loop->nOut = where_costs_set.a[i].nOut;
+			where_loop->prereq_mask = where_costs_set.a[i].prereq_mask;
+			rc = whereLoopInsert(loop_builder, where_loop);
+		}
+		WHERETRACE(0x200,
+			   ("End processing OR-clause %p\n", where_term));
 	}
 	return rc;
 }
@@ -3147,8 +3153,8 @@ static int
 whereLoopAddAll(WhereLoopBuilder * pBuilder)
 {
 	WhereInfo *pWInfo = pBuilder->pWInfo;
-	Bitmask mPrereq = 0;
-	Bitmask mPrior = 0;
+	uint64_t prereq_mask = 0;
+	uint64_t prior_mask = 0;
 	int iTab;
 	SrcList *pTabList = pWInfo->pTabList;
 	struct SrcList_item *pItem;
@@ -3162,25 +3168,23 @@ whereLoopAddAll(WhereLoopBuilder * pBuilder)
 	pNew = pBuilder->pNew;
 	whereLoopInit(pNew);
 	for (iTab = 0, pItem = pTabList->a; pItem < pEnd; iTab++, pItem++) {
-		Bitmask mUnusable = 0;
 		pNew->iTab = iTab;
-		pNew->maskSelf =
-		    sqlite3WhereGetMask(&pWInfo->sMaskSet, pItem->iCursor);
+		pNew->self_mask =
+			sql_where_get_mask(&pWInfo->sMaskSet, pItem->iCursor);
 		if (((pItem->fg.
 		      jointype | priorJointype) & (JT_LEFT | JT_CROSS)) != 0) {
 			/* This condition is true when pItem is the FROM clause term on the
 			 * right-hand-side of a LEFT or CROSS JOIN.
 			 */
-			mPrereq = mPrior;
+			prereq_mask = prior_mask;
 		}
 		priorJointype = pItem->fg.jointype;
 		{
-			rc = whereLoopAddBtree(pBuilder, mPrereq);
-		}
-		if (rc == SQLITE_OK) {
-			rc = whereLoopAddOr(pBuilder, mPrereq, mUnusable);
+			rc = sql_where_loop_add_btree(pBuilder, prereq_mask);
 		}
-		mPrior |= pNew->maskSelf;
+		if (rc == SQLITE_OK)
+			rc = sql_where_loop_add_or(pBuilder, prereq_mask);
+		prior_mask |= pNew->self_mask;
 		if (rc || db->mallocFailed)
 			break;
 	}
@@ -3189,31 +3193,43 @@ whereLoopAddAll(WhereLoopBuilder * pBuilder)
 	return rc;
 }
 
-/*
- * Examine a WherePath (with the addition of the extra WhereLoop of the 5th
- * parameters) to see if it outputs rows in the requested ORDER BY
- * (or GROUP BY) without requiring a separate sort operation.  Return N:
+/**
+ * Examine a WherePath (with the addition of the extra WhereLoop
+ * of the 5th parameters) to see if it outputs rows in the
+ * requested ORDER BY (or GROUP BY) without requiring a separate
+ * sort operation.
  *
- *   N>0:   N terms of the ORDER BY clause are satisfied
- *   N==0:  No terms of the ORDER BY clause are satisfied
- *   N<0:   Unknown yet how many terms of ORDER BY might be satisfied.
+ * Note that processing for WHERE_GROUPBY and WHERE_DISTINCTBY
+ * is not as strict.  With GROUP BY and DISTINCT the only
+ * requirement is that equivalent rows appear immediately adjacent
+ * to one another.  GROUP BY
+ * and DISTINCT do not require rows to appear in any particular
+ * order as long as equivalent rows are grouped together. Thus
+ * for GROUP BY and DISTINCT the pOrderBy terms can be matched
+ * in any order.  With ORDER BY, the pOrderBy terms must be
+ * matched in strict left-to-right order.
+ * @param where_info The WHERE clause.
+ * @param order_expr_list ORDER BY or GROUP BY or DISTINCT clause
+ *        to check.
+ * @param where_path The WherePath to check.
+ * @param wctrl_flags WHERE_GROUPBY or _DISTINCTBY or
+ *                    _ORDERBY_LIMIT.
+ * @param loop_cnt Number of entries in pPath->aLoop[].
+ * @param new_where_loop Add this WhereLoop to the end of
+ *                       pPath->aLoop[].
+ * @param rev_mask Mask of WhereLoops to run in reverse order.
  *
- * Note that processing for WHERE_GROUPBY and WHERE_DISTINCTBY is not as
- * strict.  With GROUP BY and DISTINCT the only requirement is that
- * equivalent rows appear immediately adjacent to one another.  GROUP BY
- * and DISTINCT do not require rows to appear in any particular order as long
- * as equivalent rows are grouped together.  Thus for GROUP BY and DISTINCT
- * the pOrderBy terms can be matched in any order.  With ORDER BY, the
- * pOrderBy terms must be matched in strict left-to-right order.
+ * @retval  N>0:   On N terms of the ORDER BY clause are satisfied
+ *          N==0:  No terms of the ORDER BY clause are satisfied
+ *          N<0:   Unknown yet how many terms of ORDER BY might be
+ *                 satisfied.
  */
 static i8
-wherePathSatisfiesOrderBy(WhereInfo * pWInfo,	/* The WHERE clause */
-			  ExprList * pOrderBy,	/* ORDER BY or GROUP BY or DISTINCT clause to check */
-			  WherePath * pPath,	/* The WherePath to check */
-			  u16 wctrlFlags,	/* WHERE_GROUPBY or _DISTINCTBY or _ORDERBY_LIMIT */
-			  u16 nLoop,		/* Number of entries in pPath->aLoop[] */
-			  WhereLoop * pLast,	/* Add this WhereLoop to the end of pPath->aLoop[] */
-			  Bitmask * pRevMask)	/* OUT: Mask of WhereLoops to run in reverse order */
+sql_path_match_order_by(struct WhereInfo *where_info,
+			struct ExprList *order_expr_list,
+			struct WherePath *where_path, u16 wctrl_flags,
+			u16 loop_cnt, struct WhereLoop *new_where_loop,
+			uint64_t *rev_mask)
 {
 	u8 revSet;		/* True if rev is known */
 	u8 rev;			/* Composite sort order */
@@ -3224,7 +3240,6 @@ wherePathSatisfiesOrderBy(WhereInfo * pWInfo,	/* The WHERE clause */
 	u16 eqOpMask;		/* Allowed equality operators */
 	u16 nColumn;		/* Total number of ordered columns in the index */
 	u16 nOrderBy;		/* Number terms in the ORDER BY clause */
-	int iLoop;		/* Index of WhereLoop in pPath being processed */
 	int i, j;		/* Loop counters */
 	int iCur;		/* Cursor number for current WhereLoop */
 	int iColumn;		/* A column number within table iCur */
@@ -3232,11 +3247,16 @@ wherePathSatisfiesOrderBy(WhereInfo * pWInfo,	/* The WHERE clause */
 	WhereTerm *pTerm;	/* A single term of the WHERE clause */
 	Expr *pOBExpr;		/* An expression from the ORDER BY clause */
 	Index *pIndex;		/* The index associated with pLoop */
-	sqlite3 *db = pWInfo->pParse->db;	/* Database connection */
-	Bitmask obSat = 0;	/* Mask of ORDER BY terms satisfied so far */
-	Bitmask obDone;		/* Mask of all ORDER BY terms */
-	Bitmask orderDistinctMask;	/* Mask of all well-ordered loops */
-	Bitmask ready;		/* Mask of inner loops */
+	/* Database connection. */
+	struct sqlite3 *db = where_info->pParse->db;
+	/* Mask of ORDER BY terms satisfied so far. */
+	uint64_t ob_sat_mask = 0;
+	/* Mask of all ORDER BY terms. */
+	uint64_t ob_all_mask = 0;
+	/* Mask of all well-ordered loops. */
+	uint64_t ob_dist_mask;
+	/* Mask of inner loops */
+	uint64_t ready_mask;
 
 	/*
 	 * We say the WhereLoop is "one-row" if it generates no more than one
@@ -3256,33 +3276,32 @@ wherePathSatisfiesOrderBy(WhereInfo * pWInfo,	/* The WHERE clause */
 	 * To be order-distinct, the columns must be UNIQUE and NOT NULL.
 	 */
 
-	assert(pOrderBy != 0);
-	if (nLoop && OptimizationDisabled(db, SQLITE_OrderByIdxJoin))
+	assert(order_expr_list != 0);
+	if (loop_cnt && OptimizationDisabled(db, SQLITE_OrderByIdxJoin))
 		return 0;
 
-	nOrderBy = pOrderBy->nExpr;
-	testcase(nOrderBy == BMS - 1);
-	if (nOrderBy > BMS - 1)
+	nOrderBy = order_expr_list->nExpr;
+	if (nOrderBy > COLUMN_MASK_SIZE - 1)
 		return 0;	/* Cannot optimize overly large ORDER BYs */
 	isOrderDistinct = 1;
-	obDone = MASKBIT(nOrderBy) - 1;
-	orderDistinctMask = 0;
-	ready = 0;
+	ob_all_mask = COLUMN_MASK_BIT(nOrderBy) - 1;
+	ob_dist_mask = 0;
+	ready_mask = 0;
 	eqOpMask = WO_EQ | WO_ISNULL;
-	if (wctrlFlags & WHERE_ORDERBY_LIMIT)
+	if (wctrl_flags & WHERE_ORDERBY_LIMIT)
 		eqOpMask |= WO_IN;
-	for (iLoop = 0; isOrderDistinct && obSat < obDone && iLoop <= nLoop;
-	     iLoop++) {
-		if (iLoop > 0)
-			ready |= pLoop->maskSelf;
-		if (iLoop < nLoop) {
-			pLoop = pPath->aLoop[iLoop];
-			if (wctrlFlags & WHERE_ORDERBY_LIMIT)
+	for (int loops_done = 0; isOrderDistinct && ob_sat_mask < ob_all_mask && loops_done <= loop_cnt;
+	     loops_done++) {
+		if (loops_done > 0)
+			ready_mask |= pLoop->self_mask;
+		if (loops_done < loop_cnt) {
+			pLoop = where_path->aLoop[loops_done];
+			if (wctrl_flags & WHERE_ORDERBY_LIMIT)
 				continue;
 		} else {
-			pLoop = pLast;
+			pLoop = new_where_loop;
 		}
-		iCur = pWInfo->pTabList->a[pLoop->iTab].iCursor;
+		iCur = where_info->pTabList->a[pLoop->iTab].iCursor;
 
 		/* Mark off any ORDER BY term X that is a column in the table of
 		 * the current loop for which there is term in the WHERE
@@ -3290,25 +3309,24 @@ wherePathSatisfiesOrderBy(WhereInfo * pWInfo,	/* The WHERE clause */
 		 * loops.
 		 */
 		for (i = 0; i < nOrderBy; i++) {
-			if (MASKBIT(i) & obSat)
+			if (COLUMN_MASK_BIT(i) & ob_sat_mask)
 				continue;
-			pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr);
+			pOBExpr = sqlite3ExprSkipCollate(order_expr_list->a[i].pExpr);
 			if (pOBExpr->op != TK_COLUMN)
 				continue;
 			if (pOBExpr->iTable != iCur)
 				continue;
-			pTerm =
-			    sqlite3WhereFindTerm(&pWInfo->sWC, iCur,
-						 pOBExpr->iColumn, ~ready,
-						 eqOpMask, 0);
-			if (pTerm == 0)
+			pTerm = sql_where_find_term(&where_info->sWC, iCur,
+						    pOBExpr->iColumn, ~ready_mask,
+						    eqOpMask, 0);
+			if (pTerm == NULL)
 				continue;
 			if (pTerm->eOperator == WO_IN) {
 				/* IN terms are only valid for sorting in the ORDER BY LIMIT
 				 * optimization, and then only if they are actually used
 				 * by the query plan
 				 */
-				assert(wctrlFlags & WHERE_ORDERBY_LIMIT);
+				assert(wctrl_flags & WHERE_ORDERBY_LIMIT);
 				for (j = 0;
 				     j < pLoop->nLTerm
 				     && pTerm != pLoop->aLTerm[j]; j++) {
@@ -3321,16 +3339,16 @@ wherePathSatisfiesOrderBy(WhereInfo * pWInfo,	/* The WHERE clause */
 				struct coll *coll1, *coll2;
 				bool unused;
 				uint32_t id;
-				coll1 = sql_expr_coll(pWInfo->pParse,
-						      pOrderBy->a[i].pExpr,
+				coll1 = sql_expr_coll(where_info->pParse,
+						      order_expr_list->a[i].pExpr,
 						      &unused, &id);
-				coll2 = sql_expr_coll(pWInfo->pParse,
+				coll2 = sql_expr_coll(where_info->pParse,
 						      pTerm->pExpr,
 						      &unused, &id);
 				if (coll1 != coll2)
 					continue;
 			}
-			obSat |= MASKBIT(i);
+			column_mask_set_fieldno(&ob_sat_mask, i);
 		}
 
 		if ((pLoop->wsFlags & WHERE_ONEROW) == 0) {
@@ -3428,13 +3446,11 @@ wherePathSatisfiesOrderBy(WhereInfo * pWInfo,	/* The WHERE clause */
 				 */
 				isMatch = 0;
 				for (i = 0; bOnce && i < nOrderBy; i++) {
-					if (MASKBIT(i) & obSat)
+					if (COLUMN_MASK_BIT(i) & ob_sat_mask)
 						continue;
 					pOBExpr =
-					    sqlite3ExprSkipCollate(pOrderBy-> a[i].pExpr);
-					testcase(wctrlFlags & WHERE_GROUPBY);
-					testcase(wctrlFlags & WHERE_DISTINCTBY);
-					if ((wctrlFlags & (WHERE_GROUPBY | WHERE_DISTINCTBY)) == 0)
+					    sqlite3ExprSkipCollate(order_expr_list-> a[i].pExpr);
+					if ((wctrl_flags & (WHERE_GROUPBY | WHERE_DISTINCTBY)) == 0)
 						bOnce = 0;
 					if (iColumn >= (-1)) {
 						if (pOBExpr->op != TK_COLUMN)
@@ -3450,8 +3466,8 @@ wherePathSatisfiesOrderBy(WhereInfo * pWInfo,	/* The WHERE clause */
 						bool is_found;
 						uint32_t id;
 						struct coll *coll =
-							sql_expr_coll(pWInfo->pParse,
-								      pOrderBy->a[i].pExpr,
+							sql_expr_coll(where_info->pParse,
+								      order_expr_list->a[i].pExpr,
 								      &is_found, &id);
 						struct coll *idx_coll =
 							pIndex->def->key_def->parts[j].coll;
@@ -3463,26 +3479,25 @@ wherePathSatisfiesOrderBy(WhereInfo * pWInfo,	/* The WHERE clause */
 					break;
 				}
 				if (isMatch
-				    && (wctrlFlags & WHERE_GROUPBY) == 0) {
+				    && (wctrl_flags & WHERE_GROUPBY) == 0) {
 					/* Make sure the sort order is compatible in an ORDER BY clause.
 					 * Sort order is irrelevant for a GROUP BY clause.
 					 */
 					if (revSet) {
 						if ((rev ^ revIdx) !=
-						    pOrderBy->a[i].sort_order)
+						    order_expr_list->a[i].sort_order)
 							isMatch = 0;
 					} else {
 						rev =
-						    revIdx ^ pOrderBy->a[i].
+						    revIdx ^ order_expr_list->a[i].
 						    sort_order;
 						if (rev)
-							*pRevMask |=
-							    MASKBIT(iLoop);
+							column_mask_set_fieldno(rev_mask, loops_done);
 						revSet = 1;
 					}
 				}
 				if (isMatch) {
-					obSat |= MASKBIT(i);
+					column_mask_set_fieldno(&ob_sat_mask, i);
 				} else {
 					/* No match found */
 					if (j == 0 || j < nColumn) {
@@ -3501,29 +3516,28 @@ wherePathSatisfiesOrderBy(WhereInfo * pWInfo,	/* The WHERE clause */
 		/* end-if not one-row */
 		/* Mark off any other ORDER BY terms that reference pLoop */
 		if (isOrderDistinct) {
-			orderDistinctMask |= pLoop->maskSelf;
+			ob_dist_mask |= pLoop->self_mask;
 			for (i = 0; i < nOrderBy; i++) {
 				Expr *p;
-				Bitmask mTerm;
-				if (MASKBIT(i) & obSat)
+				uint64_t mTerm;
+				if (COLUMN_MASK_BIT(i) & ob_sat_mask)
 					continue;
-				p = pOrderBy->a[i].pExpr;
+				p = order_expr_list->a[i].pExpr;
 				mTerm =
-				    sqlite3WhereExprUsage(&pWInfo->sMaskSet, p);
+				    sqlite3WhereExprUsage(&where_info->sMaskSet, p);
 				if (mTerm == 0 && !sqlite3ExprIsConstant(p))
 					continue;
-				if ((mTerm & ~orderDistinctMask) == 0) {
-					obSat |= MASKBIT(i);
-				}
+				if ((mTerm & ~ob_dist_mask) == 0)
+					column_mask_set_fieldno(&ob_sat_mask, i);
 			}
 		}
 	}			/* End the loop over all WhereLoops from outer-most down to inner-most */
-	if (obSat == obDone)
+	if (ob_sat_mask == ob_all_mask)
 		return (i8) nOrderBy;
 	if (!isOrderDistinct) {
 		for (i = nOrderBy - 1; i > 0; i--) {
-			Bitmask m = MASKBIT(i) - 1;
-			if ((obSat & m) == m)
+			uint64_t m = COLUMN_MASK_BIT(i) - 1;
+			if ((ob_sat_mask & m) == m)
 				return i;
 		}
 		return 0;
@@ -3739,12 +3753,14 @@ wherePathSolver(WhereInfo * pWInfo, LogEst nRowEst)
 				LogEst rCost;	/* Cost of path (pFrom+pWLoop) */
 				LogEst rUnsorted;	/* Unsorted cost of (pFrom+pWLoop) */
 				i8 isOrdered = pFrom->isOrdered;	/* isOrdered for (pFrom+pWLoop) */
-				Bitmask maskNew;	/* Mask of src visited by (..) */
-				Bitmask revMask = 0;	/* Mask of rev-order loops for (..) */
+				/* Mask of src visited by (..) */
+				uint64_t new_mask;
+				/* Mask of rev-order loops for (..) */
+				uint64_t rev_mask = 0;
 
-				if ((pWLoop->prereq & ~pFrom->maskLoop) != 0)
+				if ((pWLoop->prereq_mask & ~pFrom->loop_mask) != 0)
 					continue;
-				if ((pWLoop->maskSelf & pFrom->maskLoop) != 0)
+				if ((pWLoop->self_mask & pFrom->loop_mask) != 0)
 					continue;
 				if ((pWLoop->wsFlags & WHERE_AUTO_INDEX) != 0
 				    && pFrom->nRow < 10) {
@@ -3764,18 +3780,20 @@ wherePathSolver(WhereInfo * pWInfo, LogEst nRowEst)
 				    sqlite3LogEstAdd(rUnsorted,
 						     pFrom->rUnsorted);
 				nOut = pFrom->nRow + pWLoop->nOut;
-				maskNew = pFrom->maskLoop | pWLoop->maskSelf;
+				new_mask = pFrom->loop_mask | pWLoop->self_mask;
 				if (isOrdered < 0) {
 					isOrdered =
-					    wherePathSatisfiesOrderBy(pWInfo,
-								      pWInfo->pOrderBy,
-								      pFrom,
-								      pWInfo->wctrlFlags,
-								      iLoop,
-								      pWLoop,
-								      &revMask);
+						sql_path_match_order_by(pWInfo,
+									pWInfo->
+									pOrderBy,
+									pFrom,
+									pWInfo->
+									wctrlFlags,
+									iLoop,
+									pWLoop,
+									&rev_mask);
 				} else {
-					revMask = pFrom->revLoop;
+					rev_mask = pFrom->rev_loop_mask;
 				}
 				if (isOrdered >= 0 && isOrdered < nOrderBy) {
 					if (aSortCost[isOrdered] == 0) {
@@ -3812,7 +3830,7 @@ wherePathSolver(WhereInfo * pWInfo, LogEst nRowEst)
 				 * of legal values for isOrdered, -1..64.
 				 */
 				for (jj = 0, pTo = aTo; jj < nTo; jj++, pTo++) {
-					if (pTo->maskLoop == maskNew
+					if (pTo->loop_mask == new_mask
 					    && ((pTo->isOrdered ^ isOrdered) &
 						0x80) == 0) {
 						testcase(jj == nTo - 1);
@@ -3917,8 +3935,8 @@ wherePathSolver(WhereInfo * pWInfo, LogEst nRowEst)
 #endif
 				}
 				/* pWLoop is a winner.  Add it to the set of best so far */
-				pTo->maskLoop = pFrom->maskLoop | pWLoop->maskSelf;
-				pTo->revLoop = revMask;
+				pTo->loop_mask = pFrom->loop_mask | pWLoop->self_mask;
+				pTo->rev_loop_mask = rev_mask;
 				pTo->nRow = nOut;
 				pTo->rCost = rCost;
 				pTo->rUnsorted = rUnsorted;
@@ -3958,7 +3976,7 @@ wherePathSolver(WhereInfo * pWInfo, LogEst nRowEst)
 						   0 ? (pTo->isOrdered + '0') : '?');
 				if (pTo->isOrdered > 0) {
 					sqlite3DebugPrintf(" rev=0x%llx\n",
-							   pTo->revLoop);
+							   pTo->rev_loop_mask);
 				} else {
 					sqlite3DebugPrintf("\n");
 				}
@@ -3996,67 +4014,58 @@ wherePathSolver(WhereInfo * pWInfo, LogEst nRowEst)
 	if ((pWInfo->wctrlFlags & WHERE_WANT_DISTINCT) != 0
 	    && (pWInfo->wctrlFlags & WHERE_DISTINCTBY) == 0
 	    && pWInfo->eDistinct == WHERE_DISTINCT_NOOP && nRowEst) {
-		Bitmask notUsed;
-		int rc =
-		    wherePathSatisfiesOrderBy(pWInfo, pWInfo->pDistinctSet,
-					      pFrom,
-					      WHERE_DISTINCTBY, nLoop - 1,
-					      pFrom->aLoop[nLoop - 1],
-					      &notUsed);
+		uint64_t notUsed;
+		int rc = sql_path_match_order_by(pWInfo,
+						 pWInfo->pDistinctSet, pFrom,
+						 WHERE_DISTINCTBY, nLoop - 1,
+						 pFrom->aLoop[nLoop - 1],
+						 &notUsed);
 		if (rc == pWInfo->pDistinctSet->nExpr) {
 			pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
 		}
 	}
 	if (pWInfo->pOrderBy) {
 		if (pWInfo->wctrlFlags & WHERE_DISTINCTBY) {
-			if (pFrom->isOrdered == pWInfo->pOrderBy->nExpr) {
+			if (pFrom->isOrdered == pWInfo->pOrderBy->nExpr)
 				pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
-			}
 		} else {
 			pWInfo->nOBSat = pFrom->isOrdered;
-			pWInfo->revMask = pFrom->revLoop;
-			if (pWInfo->nOBSat <= 0) {
-				pWInfo->nOBSat = 0;
-				if (nLoop > 0) {
-					u32 wsFlags =
-					    pFrom->aLoop[nLoop - 1]->wsFlags;
-					if ((wsFlags & WHERE_ONEROW) == 0
-					    && (wsFlags & (WHERE_IPK | WHERE_COLUMN_IN)) != (WHERE_IPK | WHERE_COLUMN_IN)) {
-						Bitmask m = 0;
-						int rc =
-						    wherePathSatisfiesOrderBy
-						    (pWInfo, pWInfo->pOrderBy,
-						     pFrom,
-						     WHERE_ORDERBY_LIMIT,
-						     nLoop - 1,
-						     pFrom->aLoop[nLoop - 1],
-						     &m);
-						testcase(wsFlags & WHERE_IPK);
-						testcase(wsFlags &
-							 WHERE_COLUMN_IN);
-						if (rc ==
-						    pWInfo->pOrderBy->nExpr) {
-							pWInfo->
-							    bOrderedInnerLoop =
-							    1;
-							pWInfo->revMask = m;
-						}
-					}
+			pWInfo->rev_mask = pFrom->rev_loop_mask;
+			if (pWInfo->nOBSat <= 0)
+				pWInfo->nOBSat = 0;;
+			u32 wsFlags = pFrom->aLoop[nLoop - 1]->wsFlags;
+			if ((pWInfo->nOBSat <= 0 && nLoop > 0) &&
+			   ((wsFlags & WHERE_ONEROW) == 0 &&
+			   (wsFlags & (WHERE_IPK | WHERE_COLUMN_IN)) !=
+			   (WHERE_IPK | WHERE_COLUMN_IN))) {
+				uint64_t m = 0;
+				int rc;
+				rc = sql_path_match_order_by(pWInfo,
+							     pWInfo->pOrderBy,
+							     pFrom,
+							     WHERE_ORDERBY_LIMIT,
+							     nLoop - 1,
+							     pFrom->
+							     aLoop[nLoop - 1],
+							     &m);
+				if (rc == pWInfo->pOrderBy->nExpr) {
+					pWInfo-> bOrderedInnerLoop = 1;
+					pWInfo->rev_mask = m;
 				}
 			}
 		}
 		if ((pWInfo->wctrlFlags & WHERE_SORTBYGROUP)
 		    && pWInfo->nOBSat == pWInfo->pOrderBy->nExpr && nLoop > 0) {
-			Bitmask revMask = 0;
+			uint64_t rev_mask = 0;
 			int nOrder =
-			    wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy,
-						      pFrom, 0, nLoop - 1,
-						      pFrom->aLoop[nLoop - 1],
-						      &revMask);
+				sql_path_match_order_by(pWInfo, pWInfo->pOrderBy,
+							pFrom, 0, nLoop - 1,
+							pFrom->aLoop[nLoop - 1],
+							&rev_mask);
 			assert(pWInfo->sorted == 0);
 			if (nOrder == pWInfo->pOrderBy->nExpr) {
 				pWInfo->sorted = 1;
-				pWInfo->revMask = revMask;
+				pWInfo->rev_mask = rev_mask;
 			}
 		}
 	}
@@ -4142,8 +4151,8 @@ where_loop_builder_shortcut(struct WhereLoopBuilder *builder)
 	loop->wsFlags = 0;
 	loop->nSkip = 0;
 	loop->pIndex = NULL;
-	struct WhereTerm *term = sqlite3WhereFindTerm(clause, cursor, -1, 0,
-						      WO_EQ, 0);
+	struct WhereTerm *term = sql_where_find_term(clause, cursor, -1, 0,
+						     WO_EQ, 0);
 	if (term != NULL) {
 		loop->wsFlags = WHERE_COLUMN_EQ | WHERE_IPK | WHERE_ONEROW;
 		loop->aLTerm[0] = term;
@@ -4176,8 +4185,8 @@ where_loop_builder_shortcut(struct WhereLoopBuilder *builder)
 	if (loop->wsFlags) {
 		loop->nOut = (LogEst) 1;
 		where_info->a[0].pWLoop = loop;
-		loop->maskSelf = sqlite3WhereGetMask(&where_info->sMaskSet,
-						     cursor);
+		loop->self_mask = sql_where_get_mask(&where_info->sMaskSet,
+						    cursor);
 		where_info->a[0].iTabCur = cursor;
 		where_info->nRowOut = 1;
 		if (where_info->pOrderBy)
@@ -4296,7 +4305,6 @@ sqlite3WhereBegin(Parse * pParse,	/* The parser context */
 	int nTabList;		/* Number of elements in pTabList */
 	WhereInfo *pWInfo;	/* Will become the return value of this function */
 	Vdbe *v = pParse->pVdbe;	/* The virtual database engine */
-	Bitmask notReady;	/* Cursors that are not yet positioned */
 	WhereLoopBuilder sWLB;	/* The WhereLoop builder */
 	WhereMaskSet *pMaskSet;	/* The expression mask set */
 	WhereLevel *pLevel;	/* A single level in pWInfo->a[] */
@@ -4329,8 +4337,7 @@ sqlite3WhereBegin(Parse * pParse,	/* The parser context */
 	memset(&sWLB, 0, sizeof(sWLB));
 
 	/* An ORDER/GROUP BY clause of more than 63 terms cannot be optimized */
-	testcase(pOrderBy && pOrderBy->nExpr == BMS - 1);
-	if (pOrderBy && pOrderBy->nExpr >= BMS)
+	if (pOrderBy != 0 && pOrderBy->nExpr >= COLUMN_MASK_SIZE)
 		pOrderBy = 0;
 	sWLB.pOrderBy = pOrderBy;
 
@@ -4342,11 +4349,11 @@ sqlite3WhereBegin(Parse * pParse,	/* The parser context */
 	}
 
 	/* The number of tables in the FROM clause is limited by the number of
-	 * bits in a Bitmask
+	 * bits in a uint64_t
 	 */
-	testcase(pTabList->nSrc == BMS);
-	if (pTabList->nSrc > BMS) {
-		sqlite3ErrorMsg(pParse, "at most %d tables in a join", BMS);
+	if (pTabList->nSrc > COLUMN_MASK_SIZE) {
+		sqlite3ErrorMsg(pParse, "at most %d tables in a join",
+				COLUMN_MASK_SIZE);
 		return 0;
 	}
 
@@ -4361,7 +4368,7 @@ sqlite3WhereBegin(Parse * pParse,	/* The parser context */
 	 * return value. A single allocation is used to store the WhereInfo
 	 * struct, the contents of WhereInfo.a[], the WhereClause structure
 	 * and the WhereMaskSet structure. Since WhereClause contains an 8-byte
-	 * field (type Bitmask) it must be aligned on an 8-byte boundary on
+	 * field (type uint64_t) it must be aligned on an 8-byte boundary on
 	 * some architectures. Hence the ROUND8() below.
 	 */
 	nByteWInfo =
@@ -4446,9 +4453,9 @@ sqlite3WhereBegin(Parse * pParse,	/* The parser context */
 	}
 #ifdef SQLITE_DEBUG
 	for (ii = 0; ii < pTabList->nSrc; ii++) {
-		Bitmask m =
-		    sqlite3WhereGetMask(pMaskSet, pTabList->a[ii].iCursor);
-		assert(m == MASKBIT(ii));
+		uint64_t m =
+			sql_where_get_mask(pMaskSet, pTabList->a[ii].iCursor);
+		assert(m == COLUMN_MASK_BIT(ii));
 	}
 #endif
 
@@ -4514,18 +4521,16 @@ sqlite3WhereBegin(Parse * pParse,	/* The parser context */
 		}
 	}
 	if (pWInfo->pOrderBy == 0 &&
-	    (user_session->sql_flags & SQLITE_ReverseOrder) != 0) {
-		pWInfo->revMask = ALLBITS;
-	}
-	if (pParse->nErr || NEVER(db->mallocFailed)) {
+	    (user_session->sql_flags & SQLITE_ReverseOrder) != 0)
+		pWInfo->rev_mask = COLUMN_MASK_FULL;
+	if (pParse->nErr != 0 || NEVER(db->mallocFailed != 0))
 		goto whereBeginError;
-	}
 #ifdef WHERETRACE_ENABLED
 	if (sqlite3WhereTrace) {
 		sqlite3DebugPrintf("---- Solution nRow=%d", pWInfo->nRowOut);
 		if (pWInfo->nOBSat > 0) {
 			sqlite3DebugPrintf(" ORDERBY=%d,0x%llx", pWInfo->nOBSat,
-					   pWInfo->revMask);
+					   pWInfo->rev_mask);
 		}
 		switch (pWInfo->eDistinct) {
 		case WHERE_DISTINCT_UNIQUE:{
@@ -4551,10 +4556,10 @@ sqlite3WhereBegin(Parse * pParse,	/* The parser context */
 	if (pWInfo->nLevel >= 2
 	    && pDistinctSet != 0 && OptimizationEnabled(db, SQLITE_OmitNoopJoin)
 	    ) {
-		Bitmask tabUsed =
+		uint64_t tab_used_mask =
 		    sqlite3WhereExprListUsage(pMaskSet, pDistinctSet);
 		if (sWLB.pOrderBy) {
-			tabUsed |=
+			tab_used_mask |=
 			    sqlite3WhereExprListUsage(pMaskSet, sWLB.pOrderBy);
 		}
 		while (pWInfo->nLevel >= 2) {
@@ -4567,11 +4572,11 @@ sqlite3WhereBegin(Parse * pParse,	/* The parser context */
 			    && (pLoop->wsFlags & WHERE_ONEROW) == 0) {
 				break;
 			}
-			if ((tabUsed & pLoop->maskSelf) != 0)
+			if ((tab_used_mask & pLoop->self_mask) != 0)
 				break;
 			pEnd = sWLB.pWC->a + sWLB.pWC->nTerm;
 			for (pTerm = sWLB.pWC->a; pTerm < pEnd; pTerm++) {
-				if ((pTerm->prereqAll & pLoop->maskSelf) != 0
+				if ((pTerm->prereq_all_mask & pLoop->self_mask) != 0
 				    && !ExprHasProperty(pTerm->pExpr,
 							EP_FromJoin)
 				    ) {
@@ -4621,15 +4626,12 @@ sqlite3WhereBegin(Parse * pParse,	/* The parser context */
 			};
 			sqlite3OpenTable(pParse, pTabItem->iCursor, pTab, op);
 			assert(pTabItem->iCursor == pLevel->iTabCur);
-			testcase(pWInfo->eOnePass == ONEPASS_OFF
-				 && pTab->nCol == BMS - 1);
-			testcase(pWInfo->eOnePass == ONEPASS_OFF
-				 && pTab->nCol == BMS);
 			sqlite3VdbeChangeP5(v, bFordelete);
 #ifdef SQLITE_ENABLE_COLUMN_USED_MASK
 			sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed,
 					      pTabItem->iCursor, 0, 0,
-					      (const u8 *)&pTabItem->colUsed,
+					      (const u8 *)
+					      &pTabItem->column_used_mask,
 					      P4_INT64);
 #endif
 		}
@@ -4727,7 +4729,7 @@ sqlite3WhereBegin(Parse * pParse,	/* The parser context */
 					VdbeComment((v, "%s", idx_def->name));
 #ifdef SQLITE_ENABLE_COLUMN_USED_MASK
 				{
-					u64 colUsed = 0;
+					u64 column_used_mask = 0;
 					int ii, jj;
 					for (ii = 0; ii < pIx->nColumn; ii++) {
 						jj = pIx->aiColumn[ii];
@@ -4736,16 +4738,16 @@ sqlite3WhereBegin(Parse * pParse,	/* The parser context */
 						if (jj > 63)
 							jj = 63;
 						if ((pTabItem->
-						     colUsed & MASKBIT(jj)) ==
+						     column_used_mask & COLUMN_MASK_BIT(jj)) ==
 						    0)
 							continue;
-						colUsed |=
+						column_used_mask |=
 						    ((u64) 1) << (ii <
 								  63 ? ii : 63);
 					}
 					sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed,
 							      iIndexCur, 0, 0,
-							      (u8 *) & colUsed,
+							      (u8 *) & column_used_mask,
 							      P4_INT64);
 				}
 #endif				/* SQLITE_ENABLE_COLUMN_USED_MASK */
@@ -4760,7 +4762,8 @@ sqlite3WhereBegin(Parse * pParse,	/* The parser context */
 	 * loop below generates code for a single nested loop of the VM
 	 * program.
 	 */
-	notReady = ~(Bitmask) 0;
+	/* Cursors that are not yet positioned. */
+	uint64_t not_ready_mask = COLUMN_MASK_FULL;
 	for (ii = 0; ii < nTabList; ii++) {
 		int addrExplain;
 		int wsFlags;
@@ -4770,7 +4773,7 @@ sqlite3WhereBegin(Parse * pParse,	/* The parser context */
 		if ((pLevel->pWLoop->wsFlags & WHERE_AUTO_INDEX) != 0) {
 			constructAutomaticIndex(pParse, &pWInfo->sWC,
 						&pTabList->a[pLevel->iFrom],
-						notReady, pLevel);
+						not_ready_mask, pLevel);
 			if (db->mallocFailed)
 				goto whereBeginError;
 		}
@@ -4779,7 +4782,7 @@ sqlite3WhereBegin(Parse * pParse,	/* The parser context */
 		    sqlite3WhereExplainOneScan(pParse, pTabList, pLevel, ii,
 					       pLevel->iFrom, wctrlFlags);
 		pLevel->addrBody = sqlite3VdbeCurrentAddr(v);
-		notReady = sqlite3WhereCodeOneLoopStart(pWInfo, ii, notReady);
+		not_ready_mask = sql_where_code_one_loop(pWInfo, ii, not_ready_mask);
 		pWInfo->iContinue = pLevel->addrCont;
 		if ((wsFlags & WHERE_MULTI_OR) == 0
 		    && (wctrlFlags & WHERE_OR_SUBCLAUSE) == 0) {
diff --git a/src/box/sql/whereInt.h b/src/box/sql/whereInt.h
index 889a667..eed1482 100644
--- a/src/box/sql/whereInt.h
+++ b/src/box/sql/whereInt.h
@@ -105,7 +105,8 @@ struct WhereLevel {
 		Index *pCovidx;	/* Possible covering index for WHERE_MULTI_OR */
 	} u;
 	struct WhereLoop *pWLoop;	/* The selected WhereLoop object */
-	Bitmask notReady;	/* FROM entries not usable at this level */
+	/** FROM entries not usable at this level. */
+	uint64_t not_ready_mask;
 #ifdef SQLITE_ENABLE_STMT_SCANSTATUS
 	int addrVisit;		/* Address at which row is visited */
 #endif
@@ -126,8 +127,10 @@ struct WhereLevel {
  * and that minimize the overall cost.
  */
 struct WhereLoop {
-	Bitmask prereq;		/* Bitmask of other loops that must run first */
-	Bitmask maskSelf;	/* Bitmask identifying table iTab */
+	/** Bitmask of other loops that must run first. */
+	uint64_t prereq_mask;
+	/** Bitmask identifying table iTab. */
+	uint64_t self_mask;
 #ifdef SQLITE_DEBUG
 	char cId;		/* Symbolic ID of this loop for debugging use */
 #endif
@@ -159,7 +162,8 @@ struct WhereLoop {
  * See WhereOrSet for additional information
  */
 struct WhereOrCost {
-	Bitmask prereq;		/* Prerequisites */
+	/** Prerequisites mask. */
+	uint64_t prereq_mask;
 	LogEst rRun;		/* Cost of running this subquery */
 	LogEst nOut;		/* Number of outputs for this subquery */
 };
@@ -193,8 +197,10 @@ struct WhereOrSet {
  * at the end is the chosen query plan.
  */
 struct WherePath {
-	Bitmask maskLoop;	/* Bitmask of all WhereLoop objects in this path */
-	Bitmask revLoop;	/* aLoop[]s that should be reversed for ORDER BY */
+	/** Bitmask of all WhereLoop objects in this path. */
+	uint64_t loop_mask;
+	/** aLoop[]s that should be reversed for ORDER BY. */
+	uint64_t rev_loop_mask;
 	LogEst nRow;		/* Estimated number of rows generated by this path */
 	LogEst rCost;		/* Total cost of this path */
 	LogEst rUnsorted;	/* Total cost of this path ignoring sorting costs */
@@ -203,12 +209,14 @@ struct WherePath {
 };
 
 /*
- * The query generator uses an array of instances of this structure to
- * help it analyze the subexpressions of the WHERE clause.  Each WHERE
- * clause subexpression is separated from the others by AND operators,
- * usually, or sometimes subexpressions separated by OR.
+ * The query generator uses an array of instances of this
+ * structure to help it analyze the subexpressions of the WHERE
+ * clause.  Each WHERE clause subexpression is separated from the
+ * others by AND operators, usually, or sometimes subexpressions
+ * separated by OR.
  *
- * All WhereTerms are collected into a single WhereClause structure.
+ * All WhereTerms are collected into a single WhereClause
+ * structure.
  * The following identity holds:
  *
  *        WhereTerm.pWC->a[WhereTerm.idx] == WhereTerm
@@ -218,11 +226,12 @@ struct WherePath {
  *              X <op> <expr>
  *
  * where X is a column name and <op> is one of certain operators,
- * then WhereTerm.leftCursor and WhereTerm.u.leftColumn record the
- * cursor number and column number for X.  WhereTerm.eOperator records
- * the <op> using a bitmask encoding defined by WO_xxx below.  The
- * use of a bitmask encoding for the operator allows us to search
- * quickly for terms that match any of several different operators.
+ * then WhereTerm.leftCursor and WhereTerm.u.leftColumn record
+ * the cursor number and column number for X.  WhereTerm.eOperator
+ * records the <op> using a bitmask encoding defined by
+ * WO_xxx below. The use of a bitmask encoding for the operator
+ * allows us to search quickly for terms that match any of several
+ * different operators.
  *
  * A WhereTerm might also be two or more subterms connected by OR:
  *
@@ -237,20 +246,20 @@ struct WherePath {
  * to the original subexpression content and wtFlags is set up appropriately
  * but no other fields in the WhereTerm object are meaningful.
  *
- * When eOperator!=0, prereqRight and prereqAll record sets of cursor numbers,
+ * When eOperator!=0, prereq_right_mask and prereq_all_mask record sets of cursor numbers,
  * but they do so indirectly.  A single WhereMaskSet structure translates
- * cursor number into bits and the translated bit is stored in the prereq
+ * cursor number into bits and the translated bit is stored in the prereq_mask
  * fields.  The translation is used in order to maximize the number of
- * bits that will fit in a Bitmask.  The VDBE cursor numbers might be
+ * bits that will fit in a uint64_t.  The VDBE cursor numbers might be
  * spread out over the non-negative integers.  For example, the cursor
  * numbers might be 3, 8, 9, 10, 20, 23, 41, and 45.  The WhereMaskSet
  * translates these sparse cursor numbers into consecutive integers
  * beginning with 0 in order to make the best possible use of the available
- * bits in the Bitmask.  So, in the example above, the cursor numbers
+ * bits in the uint64_t.  So, in the example above, the cursor numbers
  * would be mapped into integers 0 through 7.
  *
  * The number of terms in a join is limited by the number of bits
- * in prereqRight and prereqAll.  The default is 64 bits, hence SQLite
+ * in prereq_right_mask and prereq_all_mask.  The default is 64 bits, hence SQLite
  * is only able to process joins with 64 or fewer tables.
  */
 struct WhereTerm {
@@ -268,8 +277,10 @@ struct WhereTerm {
 		WhereOrInfo *pOrInfo;	/* Extra information if (eOperator & WO_OR)!=0 */
 		WhereAndInfo *pAndInfo;	/* Extra information if (eOperator& WO_AND)!=0 */
 	} u;
-	Bitmask prereqRight;	/* Bitmask of tables used by pExpr->pRight */
-	Bitmask prereqAll;	/* Bitmask of tables referenced by pExpr */
+	/** Bitmask of tables used by pExpr->pRight. */
+	uint64_t prereq_right_mask;
+	/** Bitmask of tables referenced by pExpr. */
+	uint64_t prereq_all_mask;
 };
 
 /*
@@ -340,7 +351,8 @@ struct WhereClause {
  */
 struct WhereOrInfo {
 	WhereClause wc;		/* Decomposition into subterms */
-	Bitmask indexable;	/* Bitmask of all indexable tables in the clause */
+	/** Bitmask of all indexable_mask tables in the clause. */
+	uint64_t indexable_mask;
 };
 
 /*
@@ -379,7 +391,8 @@ struct WhereAndInfo {
  */
 struct WhereMaskSet {
 	int n;			/* Number of assigned cursor values */
-	int ix[BMS];		/* Cursor assigned to each bit */
+	/** Cursor assigned to each bit. */
+	int ix[COLUMN_MASK_SIZE];
 };
 
 /*
@@ -431,29 +444,67 @@ struct WhereInfo {
 	u8 bOrderedInnerLoop;	/* True if only the inner-most loop is ordered */
 	int iTop;		/* The very beginning of the WHERE loop */
 	WhereLoop *pLoops;	/* List of all WhereLoop objects */
-	Bitmask revMask;	/* Mask of ORDER BY terms that need reversing */
+	/** Mask of ORDER BY terms that need reversing. */
+	uint64_t rev_mask;
 	LogEst nRowOut;		/* Estimated number of output rows */
 	WhereClause sWC;	/* Decomposition of the WHERE clause */
 	WhereMaskSet sMaskSet;	/* Map cursor numbers to bitmasks */
 	WhereLevel a[1];	/* Information about each nest loop in WHERE */
 };
 
-/*
- * Private interfaces - callable only by other where.c routines.
- *
- * where.c:
+/**
+ * Return the bitmask for the given cursor number.
+ * @param mask_set Where masks assigned for cursors.
+ * @param cursor Cursor to get mask if any.
+ * @retval Return 0 if iCursor is not in the set.
  */
-Bitmask sqlite3WhereGetMask(WhereMaskSet *, int);
+uint64_t
+sql_where_get_mask(struct WhereMaskSet *mask_set, int cursor);
+
 #ifdef WHERETRACE_ENABLED
 void sqlite3WhereClausePrint(WhereClause * pWC);
 #endif
-WhereTerm *sqlite3WhereFindTerm(WhereClause * pWC,	/* The WHERE clause to be searched */
-				int iCur,	/* Cursor number of LHS */
-				int iColumn,	/* Column number of LHS */
-				Bitmask notReady,	/* RHS must not overlap with this mask */
-				u32 op,	/* Mask of WO_xx values describing operator */
-				Index * pIdx	/* Must be compatible with this index, if not NULL */
-    );
+
+/**
+ * Search for a term in the WHERE clause that is of the form
+ * "X <op> <expr>" where X is a reference to the @column of table
+ * @cursor or of @index if @index != NULL and <op> is one of the
+ * WO_xx operator codes specified by the op parameter. Return a
+ * pointer to the term. Return 0 if not found.
+ *
+ * If @index != NULL then it must be one of the indexes of table
+ * @cursor. Search for terms matching the @column-th column of
+ * @index rather than the @column-th column of table @cursor.
+ *
+ * The term returned might by Y=<expr> if there is another
+ * constraint in the WHERE clause that specifies that X=Y. Any
+ * such constraints will be identified by the WO_EQUIV bit in the
+ * pTerm->eOperator field.  The aiCur[]/iaColumn[] arrays hold X
+ * and all its equivalents. There are 11 slots in
+ * aiCur[]/aiColumn[] so that means we can look for X plus up to
+ * 10 other equivalent values. Hence a search for X will return
+ * <expr> if X=A1 and A1=A2 and A2=A3 and ... and A9=A10 and
+ * A10=<expr>.
+ *
+ * If there are multiple terms in the WHERE clause of the form
+ * "X <op> <expr>" then try for the one with no dependencies on
+ * <expr> - in other words where <expr> is a constant expression
+ * of some kind.  Only return entries of the form "X <op> Y"
+ * where Y is a column in another table if no terms of the form
+ * "X <op> <const-expr>" exist.   If no terms with a constant RHS
+ * exist, try to return a term that does not use WO_EQUIV.
+ *
+ * @param where The WHERE clause to be searched.
+ * @param cursor Cursor number of LHS.
+ * @param column Column number of LHS.
+ * @param is_not_ready RHS must not overlap with this mask.
+ * @param op Mask of WO_xx values describing operator.
+ * @param index Must be compatible with this index, if not NULL.
+ * @retval not NULL WhereTerm pointer on found, NULL otherwise.
+ */
+struct WhereTerm *
+sql_where_find_term(struct WhereClause *where, int cursor, int column,
+		    uint64_t is_not_ready, u32 op, struct Index *index);
 
 /* wherecode.c: */
 int sqlite3WhereExplainOneScan(Parse * pParse,	/* Parse context */
@@ -472,22 +523,30 @@ void sqlite3WhereAddScanStatus(Vdbe * v,	/* Vdbe to add scanstatus entry to */
 #else
 #define sqlite3WhereAddScanStatus(a, b, c, d) ((void)d)
 #endif
-Bitmask sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about the WHERE clause */
-				     int iLevel,	/* Which level of pWInfo->a[] should be coded */
-				     Bitmask notReady	/* Which tables are currently available */
-    );
+
+/**
+ * Generate code for the start of the iLevel-th loop in the WHERE clause
+ * implementation described by pWInfo.
+ *
+ * @param where_info Complete information about the WHERE clause.
+ * @param level Which level of pWInfo->a[] should be coded.
+ * @param not_ready_mask Which tables are currently available.
+ */
+uint64_t
+sql_where_code_one_loop(struct WhereInfo *where_info, int level,
+			uint64_t not_ready_mask);
 
 /* whereexpr.c: */
 void sqlite3WhereClauseInit(WhereClause *, WhereInfo *);
 void sqlite3WhereClauseClear(WhereClause *);
 void sqlite3WhereSplit(WhereClause *, Expr *, u8);
-Bitmask sqlite3WhereExprUsage(WhereMaskSet *, Expr *);
-Bitmask sqlite3WhereExprListUsage(WhereMaskSet *, ExprList *);
+uint64_t sqlite3WhereExprUsage(WhereMaskSet *, Expr *);
+uint64_t sqlite3WhereExprListUsage(WhereMaskSet *, ExprList *);
 void sqlite3WhereExprAnalyze(SrcList *, WhereClause *);
 void sqlite3WhereTabFuncArgs(Parse *, struct SrcList_item *, WhereClause *);
 
 /*
- * Bitmasks for the operators on WhereTerm objects.  These are all
+ * uint64_ts for the operators on WhereTerm objects.  These are all
  * operators that are of interest to the query planner.  An
  * OR-ed combination of these values can be used when searching for
  * particular WhereTerms within a WhereClause.
diff --git a/src/box/sql/wherecode.c b/src/box/sql/wherecode.c
index 13a045c..0e0ef89 100644
--- a/src/box/sql/wherecode.c
+++ b/src/box/sql/wherecode.c
@@ -360,7 +360,7 @@ disableTerm(WhereLevel * pLevel, WhereTerm * pTerm)
 	       && (pTerm->wtFlags & TERM_CODED) == 0
 	       && (pLevel->iLeftJoin == 0
 		   || ExprHasProperty(pTerm->pExpr, EP_FromJoin))
-	       && (pLevel->notReady & pTerm->prereqAll) == 0) {
+	       && (pLevel->not_ready_mask & pTerm->prereq_all_mask) == 0) {
 		if (nLoop && (pTerm->wtFlags & TERM_LIKE) != 0) {
 			pTerm->wtFlags |= TERM_LIKECOND;
 		} else {
@@ -883,46 +883,43 @@ codeExprOrVector(Parse * pParse, Expr * p, int iReg, int nReg)
 	}
 }
 
-/*
- * Generate code for the start of the iLevel-th loop in the WHERE clause
- * implementation described by pWInfo.
- */
-Bitmask
-sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about the WHERE clause */
-			     int iLevel,	/* Which level of pWInfo->a[] should be coded */
-			     Bitmask notReady)	/* Which tables are currently available */
+
+uint64_t
+sql_where_code_one_loop(struct WhereInfo *where_info, int level,
+			uint64_t not_ready_mask)
 {
 	int j, k;		/* Loop counters */
-	int iCur;		/* The VDBE cursor for the table */
 	int addrNxt;		/* Where to jump to continue with the next IN case */
 	int omitTable;		/* True if we use the index only */
-	int bRev;		/* True if we need to scan in reverse order */
-	WhereLevel *pLevel;	/* The where level to be coded */
-	WhereLoop *pLoop;	/* The WhereLoop object being coded */
-	WhereClause *pWC;	/* Decomposition of the entire WHERE clause */
 	WhereTerm *pTerm;	/* A WHERE clause term */
-	Parse *pParse;		/* Parsing context */
-	sqlite3 *db;		/* Database connection */
-	Vdbe *v;		/* The prepared stmt under constructions */
-	struct SrcList_item *pTabItem;	/* FROM clause term being coded */
 	int addrBrk;		/* Jump here to break out of the loop */
 	int addrCont;		/* Jump here to continue with next cycle */
 
-	pParse = pWInfo->pParse;
-	v = pParse->pVdbe;
-	pWC = &pWInfo->sWC;
-	db = pParse->db;
-	pLevel = &pWInfo->a[iLevel];
-	pLoop = pLevel->pWLoop;
-	pTabItem = &pWInfo->pTabList->a[pLevel->iFrom];
-	iCur = pTabItem->iCursor;
-	pLevel->notReady =
-	    notReady & ~sqlite3WhereGetMask(&pWInfo->sMaskSet, iCur);
-	bRev = (pWInfo->revMask >> iLevel) & 1;
-	omitTable = (pLoop->wsFlags & WHERE_IDX_ONLY) != 0
-	    && (pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE) == 0;
-	VdbeModuleComment((v, "Begin WHERE-loop%d: %s", iLevel,
-			   pTabItem->pTab->zName));
+	/* Parsing context. */
+	struct Parse *parser = where_info->pParse;
+	/* The prepared stmt under constructions. */
+	struct Vdbe *v = parser->pVdbe;
+	/* Decomposition of the entire WHERE clause. */
+	struct WhereClause *where_clause = &where_info->sWC;
+	/* Database connection. */
+	struct sqlite3 *db = parser->db;
+	/* The where level to be coded. */
+	struct WhereLevel *where_level = &where_info->a[level];
+	/* The WhereLoop object being coded. */
+	struct WhereLoop *where_loop = where_level->pWLoop;
+	/* FROM clause term being coded. */
+	struct SrcList_item *src_list_table =
+		&where_info->pTabList->a[where_level->iFrom];
+	/* The VDBE cursor for the table. */
+	int cursor = src_list_table->iCursor;
+	where_level->not_ready_mask =
+	    not_ready_mask & ~sql_where_get_mask(&where_info->sMaskSet, cursor);
+	/* True if we need to scan in reverse order. */
+	int is_reversed = (where_info->rev_mask >> level) & 1;
+	omitTable = (where_loop->wsFlags & WHERE_IDX_ONLY) != 0 &&
+		    (where_info->wctrlFlags & WHERE_OR_SUBCLAUSE) == 0;
+	VdbeModuleComment((v, "Begin WHERE-loop%d: %s", level,
+			   src_list_table->pTab->zName));
 
 	/* Create labels for the "break" and "continue" instructions
 	 * for the current loop.  Jump to addrBrk to break out of a loop.
@@ -934,29 +931,33 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 	 * there are no IN operators in the constraints, the "addrNxt" label
 	 * is the same as "addrBrk".
 	 */
-	addrBrk = pLevel->addrBrk = pLevel->addrNxt = sqlite3VdbeMakeLabel(v);
-	addrCont = pLevel->addrCont = sqlite3VdbeMakeLabel(v);
+	addrBrk = where_level->addrBrk = where_level->addrNxt =
+		sqlite3VdbeMakeLabel(v);
+	addrCont = where_level->addrCont = sqlite3VdbeMakeLabel(v);
 
 	/* If this is the right table of a LEFT OUTER JOIN, allocate and
 	 * initialize a memory cell that records if this table matches any
 	 * row of the left table of the join.
 	 */
-	if (pLevel->iFrom > 0 && (pTabItem[0].fg.jointype & JT_LEFT) != 0) {
-		pLevel->iLeftJoin = ++pParse->nMem;
-		sqlite3VdbeAddOp2(v, OP_Integer, 0, pLevel->iLeftJoin);
+	if (where_level->iFrom > 0 &&
+	   (src_list_table[0].fg.jointype & JT_LEFT) != 0) {
+		where_level->iLeftJoin = ++parser->nMem;
+		sqlite3VdbeAddOp2(v, OP_Integer, 0, where_level->iLeftJoin);
 		VdbeComment((v, "init LEFT JOIN no-match flag"));
 	}
 
 	/* Special case of a FROM clause subquery implemented as a co-routine */
-	if (pTabItem->fg.viaCoroutine) {
-		int regYield = pTabItem->regReturn;
+	if (src_list_table->fg.viaCoroutine) {
+		int regYield = src_list_table->regReturn;
 		sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0,
-				  pTabItem->addrFillSub);
-		pLevel->p2 = sqlite3VdbeAddOp2(v, OP_Yield, regYield, addrBrk);
+				  src_list_table->addrFillSub);
+		where_level->p2 =
+			sqlite3VdbeAddOp2(v, OP_Yield, regYield, addrBrk);
 		VdbeCoverage(v);
-		VdbeComment((v, "next row of \"%s\"", pTabItem->pTab->def->name));
-		pLevel->op = OP_Goto;
-	} else if (pLoop->wsFlags & WHERE_INDEXED) {
+		VdbeComment((v, "next row of \"%s\"",
+			    src_list_table->pTab->def->name));
+		where_level->op = OP_Goto;
+	} else if (where_loop->wsFlags & WHERE_INDEXED) {
 		/* Case 4: A scan using an index.
 		 *
 		 *         The WHERE clause may contain zero or more equality
@@ -991,22 +992,25 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 		static const u8 aStartOp[] = {
 			0,
 			0,
-			OP_Rewind,	/* 2: (!start_constraints && startEq &&  !bRev) */
-			OP_Last,	/* 3: (!start_constraints && startEq &&   bRev) */
-			OP_SeekGT,	/* 4: (start_constraints  && !startEq && !bRev) */
-			OP_SeekLT,	/* 5: (start_constraints  && !startEq &&  bRev) */
-			OP_SeekGE,	/* 6: (start_constraints  &&  startEq && !bRev) */
-			OP_SeekLE	/* 7: (start_constraints  &&  startEq &&  bRev) */
+			OP_Rewind,	/* 2: (!start_constraints && startEq &&  !is_reversed) */
+			OP_Last,	/* 3: (!start_constraints && startEq &&   is_reversed) */
+			OP_SeekGT,	/* 4: (start_constraints  && !startEq && !is_reversed) */
+			OP_SeekLT,	/* 5: (start_constraints  && !startEq &&  is_reversed) */
+			OP_SeekGE,	/* 6: (start_constraints  &&  startEq && !is_reversed) */
+			OP_SeekLE	/* 7: (start_constraints  &&  startEq &&  is_reversed) */
 		};
 		static const u8 aEndOp[] = {
-			OP_IdxGE,	/* 0: (end_constraints && !bRev && !endEq) */
-			OP_IdxGT,	/* 1: (end_constraints && !bRev &&  endEq) */
-			OP_IdxLE,	/* 2: (end_constraints &&  bRev && !endEq) */
-			OP_IdxLT,	/* 3: (end_constraints &&  bRev &&  endEq) */
+			OP_IdxGE,	/* 0: (end_constraints && !is_reversed && !endEq) */
+			OP_IdxGT,	/* 1: (end_constraints && !is_reversed &&  endEq) */
+			OP_IdxLE,	/* 2: (end_constraints &&  is_reversed && !endEq) */
+			OP_IdxLT,	/* 3: (end_constraints &&  is_reversed &&  endEq) */
 		};
-		u16 nEq = pLoop->nEq;	/* Number of == or IN terms */
-		u16 nBtm = pLoop->nBtm;	/* Length of BTM vector */
-		u16 nTop = pLoop->nTop;	/* Length of TOP vector */
+		/* Number of == or IN terms. */
+		u16 eq_cnt = where_loop->nEq;
+		/* Length of BTM vector */
+		u16 btm_cnt = where_loop->nBtm;
+		/* Length of TOP vector */
+		u16 top_cnt = where_loop->nTop;
 		int regBase;	/* Base register holding constraint values */
 		WhereTerm *pRangeStart = 0;	/* Inequality constraint at range start */
 		WhereTerm *pRangeEnd = 0;	/* Inequality constraint at range end */
@@ -1026,31 +1030,31 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 					      * to integer type, used for IPK.
 					      */
 
-		struct Index *pIdx = pLoop->pIndex;
-		struct index_def *idx_def = pLoop->index_def;
-		assert(pIdx != NULL || idx_def != NULL);
-		iIdxCur = pLevel->iIdxCur;
-		assert(nEq >= pLoop->nSkip);
+		struct Index *index = where_loop->pIndex;
+		struct index_def *idx_def = where_loop->index_def;
+		assert(index != NULL || idx_def != NULL);
+		iIdxCur = where_level->iIdxCur;
+		assert(eq_cnt >= where_loop->nSkip);
 
 		/* If this loop satisfies a sort order (pOrderBy) request that
 		 * was passed to this function to implement a "SELECT min(x) ..."
 		 * query, then the caller will only allow the loop to run for
 		 * a single iteration. This means that the first row returned
 		 * should not have a NULL value stored in 'x'. If column 'x' is
-		 * the first one after the nEq equality constraints in the index,
+		 * the first one after the eq_cnt equality constraints in the index,
 		 * this requires some special handling.
 		 */
-		assert(pWInfo->pOrderBy == 0
-		       || pWInfo->pOrderBy->nExpr == 1
-		       || (pWInfo->wctrlFlags & WHERE_ORDERBY_MIN) == 0);
+		assert(where_info->pOrderBy == 0 ||
+		       where_info->pOrderBy->nExpr == 1 ||
+		       (where_info->wctrlFlags & WHERE_ORDERBY_MIN) == 0);
 		uint32_t part_count;
-		if (pIdx != NULL)
-			part_count = pIdx->def->key_def->part_count;
+		if (index != NULL)
+			part_count = index->def->key_def->part_count;
 		else
 			part_count = idx_def->key_def->part_count;
-		if ((pWInfo->wctrlFlags & WHERE_ORDERBY_MIN) != 0 &&
-		    pWInfo->nOBSat > 0 && part_count > nEq) {
-			j = pIdx->def->key_def->parts[nEq].fieldno;
+		if ((where_info->wctrlFlags & WHERE_ORDERBY_MIN) != 0 &&
+		    where_info->nOBSat > 0 && part_count > eq_cnt) {
+			j = index->def->key_def->parts[eq_cnt].fieldno;
 			/* Allow seek for column with `NOT NULL` == false attribute.
 			 * If a column may contain NULL-s, the comparator installed
 			 * by Tarantool is prepared to seek using a NULL value.
@@ -1061,8 +1065,8 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 			 * FYI: entries in an index are ordered as follows:
 			 *      NULL, ... NULL, min_value, ...
 			 */
-			if (pIdx->pTable->def->fields[j].is_nullable) {
-				assert(pLoop->nSkip == 0);
+			if (index->pTable->def->fields[j].is_nullable) {
+				assert(where_loop->nSkip == 0);
 				bSeekPastNull = 1;
 				nExtraReg = 1;
 			}
@@ -1071,43 +1075,43 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 		/* Find any inequality constraint terms for the start and end
 		 * of the range.
 		 */
-		j = nEq;
-		if (pLoop->wsFlags & WHERE_BTM_LIMIT) {
-			pRangeStart = pLoop->aLTerm[j++];
-			nExtraReg = MAX(nExtraReg, pLoop->nBtm);
+		j = eq_cnt;
+		if (where_loop->wsFlags & WHERE_BTM_LIMIT) {
+			pRangeStart = where_loop->aLTerm[j++];
+			nExtraReg = MAX(nExtraReg, where_loop->nBtm);
 			/* Like optimization range constraints always occur in pairs */
 			assert((pRangeStart->wtFlags & TERM_LIKEOPT) == 0 ||
-			       (pLoop->wsFlags & WHERE_TOP_LIMIT) != 0);
+			       (where_loop->wsFlags & WHERE_TOP_LIMIT) != 0);
 		}
-		if (pLoop->wsFlags & WHERE_TOP_LIMIT) {
-			pRangeEnd = pLoop->aLTerm[j++];
-			nExtraReg = MAX(nExtraReg, pLoop->nTop);
+		if (where_loop->wsFlags & WHERE_TOP_LIMIT) {
+			pRangeEnd = where_loop->aLTerm[j++];
+			nExtraReg = MAX(nExtraReg, where_loop->nTop);
 #ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
 			if ((pRangeEnd->wtFlags & TERM_LIKEOPT) != 0) {
 				assert(pRangeStart != 0);	/* LIKE opt constraints */
 				assert(pRangeStart->wtFlags & TERM_LIKEOPT);	/* occur in pairs */
-				pLevel->iLikeRepCntr = (u32)++ pParse->nMem;
+				where_level->iLikeRepCntr = (u32)++ parser->nMem;
 				sqlite3VdbeAddOp2(v, OP_Integer, 1,
-						  (int)pLevel->iLikeRepCntr);
+						  (int)where_level->iLikeRepCntr);
 				VdbeComment((v, "LIKE loop counter"));
-				pLevel->addrLikeRep = sqlite3VdbeCurrentAddr(v);
+				where_level->addrLikeRep = sqlite3VdbeCurrentAddr(v);
 				/* iLikeRepCntr actually stores 2x the counter register number.  The
 				 * bottom bit indicates whether the search order is ASC or DESC.
 				 */
-				testcase(bRev);
-				testcase(pIdx->aSortOrder[nEq] ==
+				testcase(index->aSortOrder[eq_cnt] ==
 					 SORT_ORDER_DESC);
-				assert((bRev & ~1) == 0);
-				struct key_def *def = pIdx->def->key_def;
-				pLevel->iLikeRepCntr <<= 1;
-				pLevel->iLikeRepCntr |=
-					bRev ^ (def->parts[nEq].sort_order ==
-						SORT_ORDER_DESC);
+				assert((is_reversed & ~1) == 0);
+				struct key_def *def = index->def->key_def;
+				where_level->iLikeRepCntr <<= 1;
+				where_level->iLikeRepCntr |=
+					is_reversed ^
+					(def->parts[eq_cnt].sort_order ==
+					SORT_ORDER_DESC);
 			}
 #endif
 			if (pRangeStart == 0) {
-				j = pIdx->def->key_def->parts[nEq].fieldno;
-				if (pIdx->pTable->def->fields[j].is_nullable)
+				j = index->def->key_def->parts[eq_cnt].fieldno;
+				if (index->pTable->def->fields[j].is_nullable)
 					bSeekPastNull = 1;
 			}
 		}
@@ -1118,12 +1122,12 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 		 * a forward order scan on a descending index, interchange the
 		 * start and end terms (pRangeStart and pRangeEnd).
 		 */
-		if ((nEq < part_count &&
-		     bRev == (pIdx->def->key_def->parts[nEq].sort_order ==
-			      SORT_ORDER_ASC)) || (bRev && part_count == nEq)) {
+		if ((eq_cnt < part_count && is_reversed ==
+		    (index->def->key_def->parts[eq_cnt].sort_order ==
+		    SORT_ORDER_ASC)) || (is_reversed && part_count == eq_cnt)) {
 			SWAP(pRangeEnd, pRangeStart);
 			SWAP(bSeekPastNull, bStopAtNull);
-			SWAP(nBtm, nTop);
+			SWAP(btm_cnt, top_cnt);
 		}
 
 		/* Generate code to evaluate all constraint terms using == or IN
@@ -1131,13 +1135,12 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 		 * starting at regBase.
 		 */
 		regBase =
-		    codeAllEqualityTerms(pParse, pLevel, bRev, nExtraReg,
-					 &zStartAff);
-		assert(zStartAff == 0 || sqlite3Strlen30(zStartAff) >= nEq);
-		if (zStartAff && nTop) {
-			zEndAff = sqlite3DbStrDup(db, &zStartAff[nEq]);
-		}
-		addrNxt = pLevel->addrNxt;
+		    codeAllEqualityTerms(parser, where_level, is_reversed,
+					 nExtraReg, &zStartAff);
+		assert(zStartAff == 0 || sqlite3Strlen30(zStartAff) >= eq_cnt);
+		if (zStartAff && top_cnt)
+			zEndAff = sqlite3DbStrDup(db, &zStartAff[eq_cnt]);
+		addrNxt = where_level->addrNxt;
 
 		testcase(pRangeStart && (pRangeStart->eOperator & WO_LE) != 0);
 		testcase(pRangeStart && (pRangeStart->eOperator & WO_GE) != 0);
@@ -1146,37 +1149,37 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 		startEq = !pRangeStart
 		    || pRangeStart->eOperator & (WO_LE | WO_GE);
 		endEq = !pRangeEnd || pRangeEnd->eOperator & (WO_LE | WO_GE);
-		start_constraints = pRangeStart || nEq > 0;
+		start_constraints = pRangeStart || eq_cnt > 0;
 
 		/* Seek the index cursor to the start of the range. */
-		nConstraint = nEq;
+		nConstraint = eq_cnt;
 		if (pRangeStart) {
 			Expr *pRight = pRangeStart->pExpr->pRight;
-			codeExprOrVector(pParse, pRight, regBase + nEq, nBtm);
+			codeExprOrVector(parser, pRight, regBase + eq_cnt, btm_cnt);
 
-			whereLikeOptimizationStringFixup(v, pLevel,
+			whereLikeOptimizationStringFixup(v, where_level,
 							 pRangeStart);
 			if ((pRangeStart->wtFlags & TERM_VNULL) == 0
 			    && sqlite3ExprCanBeNull(pRight)) {
-				sqlite3VdbeAddOp2(v, OP_IsNull, regBase + nEq,
+				sqlite3VdbeAddOp2(v, OP_IsNull, regBase + eq_cnt,
 						  addrNxt);
 				VdbeCoverage(v);
 			}
 
 			if (zStartAff) {
-				updateRangeAffinityStr(pRight, nBtm,
-						       &zStartAff[nEq]);
+				updateRangeAffinityStr(pRight, btm_cnt,
+						       &zStartAff[eq_cnt]);
 			}
-			nConstraint += nBtm;
+			nConstraint += btm_cnt;
 			testcase(pRangeStart->wtFlags & TERM_VIRTUAL);
 			if (sqlite3ExprIsVector(pRight) == 0) {
-				disableTerm(pLevel, pRangeStart);
+				disableTerm(where_level, pRangeStart);
 			} else {
 				startEq = 1;
 			}
 			bSeekPastNull = 0;
 		} else if (bSeekPastNull) {
-			sqlite3VdbeAddOp2(v, OP_Null, 0, regBase + nEq);
+			sqlite3VdbeAddOp2(v, OP_Null, 0, regBase + eq_cnt);
 			nConstraint++;
 			startEq = 0;
 			start_constraints = 1;
@@ -1184,7 +1187,7 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 		struct Index *pk = NULL;
 		struct index_def *idx_pk = NULL;
 		char affinity;
-		if (pIdx == NULL) {
+		if (index == NULL) {
 			struct space *space = space_cache_find(idx_def->space_id);
 			assert(space != NULL);
 			idx_pk = space->index[0]->def;
@@ -1199,9 +1202,9 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 					affinity = AFFINITY_BLOB;
 			}
 		} else {
-			pk = sqlite3PrimaryKeyIndex(pIdx->pTable);
+			pk = sqlite3PrimaryKeyIndex(index->pTable);
 			uint32_t fieldno = pk->def->key_def->parts[0].fieldno;
-			affinity = pIdx->pTable->def->fields[fieldno].affinity;
+			affinity = index->pTable->def->fields[fieldno].affinity;
 		}
 
 		uint32_t pk_part_count;
@@ -1215,10 +1218,10 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 			 * here: try to loosely convert FLOAT to INT. If RHS type
 			 * is not INT or FLOAT - skip this ites, i.e. goto addrNxt.
 			 */
-			int limit = pRangeStart == NULL ? nEq : nEq + 1;
+			int limit = pRangeStart == NULL ? eq_cnt : eq_cnt + 1;
 			for (int i = 0; i < limit; i++) {
-				if ((pIdx != NULL &&
-				     pIdx->def->key_def->parts[i].fieldno ==
+				if ((index != NULL &&
+				     index->def->key_def->parts[i].fieldno ==
 				     pk->def->key_def->parts[0].fieldno) ||
 				    (idx_pk != NULL &&
 				     idx_def->key_def->parts[i].fieldno ==
@@ -1226,7 +1229,7 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 					/* Here: we know for sure that table has INTEGER
 					   PRIMARY KEY, single column, and Index we're
 					   trying to use for scan contains this column. */
-					if (i < nEq)
+					if (i < eq_cnt)
 						sqlite3VdbeAddOp2(v, OP_MustBeInt, regBase + i, addrNxt);
 					else
 						force_integer_reg = regBase + i;
@@ -1234,16 +1237,16 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 				}
 			}
 		}
-		codeApplyAffinity(pParse, regBase, nConstraint - bSeekPastNull,
+		codeApplyAffinity(parser, regBase, nConstraint - bSeekPastNull,
 				  zStartAff);
-		if (pLoop->nSkip > 0 && nConstraint == pLoop->nSkip) {
+		if (where_loop->nSkip > 0 && nConstraint == where_loop->nSkip) {
 			/* The skip-scan logic inside the call to codeAllEqualityConstraints()
 			 * above has already left the cursor sitting on the correct row,
 			 * so no further seeking is needed
 			 */
 		} else {
 			op = aStartOp[(start_constraints << 2) +
-				      (startEq << 1) + bRev];
+				      (startEq << 1) + is_reversed];
 			assert(op != 0);
 			sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase,
 					     nConstraint);
@@ -1273,35 +1276,36 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 		/* Load the value for the inequality constraint at the end of the
 		 * range (if any).
 		 */
-		nConstraint = nEq;
+		nConstraint = eq_cnt;
 		if (pRangeEnd) {
 			Expr *pRight = pRangeEnd->pExpr->pRight;
-			sqlite3ExprCacheRemove(pParse, regBase + nEq, 1);
-			codeExprOrVector(pParse, pRight, regBase + nEq, nTop);
-			whereLikeOptimizationStringFixup(v, pLevel, pRangeEnd);
+			sqlite3ExprCacheRemove(parser, regBase + eq_cnt, 1);
+			codeExprOrVector(parser, pRight, regBase + eq_cnt, top_cnt);
+			whereLikeOptimizationStringFixup(v, where_level,
+							 pRangeEnd);
 			if ((pRangeEnd->wtFlags & TERM_VNULL) == 0
 			    && sqlite3ExprCanBeNull(pRight)) {
-				sqlite3VdbeAddOp2(v, OP_IsNull, regBase + nEq,
+				sqlite3VdbeAddOp2(v, OP_IsNull, regBase + eq_cnt,
 						  addrNxt);
 				VdbeCoverage(v);
 			}
 			if (zEndAff) {
-				updateRangeAffinityStr(pRight, nTop, zEndAff);
-				codeApplyAffinity(pParse, regBase + nEq, nTop,
+				updateRangeAffinityStr(pRight, top_cnt, zEndAff);
+				codeApplyAffinity(parser, regBase + eq_cnt, top_cnt,
 						  zEndAff);
 			} else {
-				assert(pParse->db->mallocFailed);
+				assert(parser->db->mallocFailed);
 			}
-			nConstraint += nTop;
+			nConstraint += top_cnt;
 			testcase(pRangeEnd->wtFlags & TERM_VIRTUAL);
 
 			if (sqlite3ExprIsVector(pRight) == 0) {
-				disableTerm(pLevel, pRangeEnd);
+				disableTerm(where_level, pRangeEnd);
 			} else {
 				endEq = 1;
 			}
 		} else if (bStopAtNull) {
-			sqlite3VdbeAddOp2(v, OP_Null, 0, regBase + nEq);
+			sqlite3VdbeAddOp2(v, OP_Null, 0, regBase + eq_cnt);
 			endEq = 0;
 			nConstraint++;
 		}
@@ -1309,11 +1313,11 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 		sqlite3DbFree(db, zEndAff);
 
 		/* Top of the loop body */
-		pLevel->p2 = sqlite3VdbeCurrentAddr(v);
+		where_level->p2 = sqlite3VdbeCurrentAddr(v);
 
 		/* Check if the index cursor is past the end of the range. */
 		if (nConstraint) {
-			op = aEndOp[bRev * 2 + endEq];
+			op = aEndOp[is_reversed * 2 + endEq];
 			sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase,
 					     nConstraint);
 			testcase(op == OP_IdxGT);
@@ -1328,40 +1332,44 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 
 		/* Seek the table cursor, if required */
 		if (omitTable) {
-			/* pIdx is a covering index.  No need to access the main table. */
-		}  else if (iCur != iIdxCur) {
-			Index *pPk = sqlite3PrimaryKeyIndex(pIdx->pTable);
+			/*
+			 * Index is a covering index.
+			 * No need to access the main table.
+			 */
+		}  else if (cursor != iIdxCur) {
+			Index *pPk = sqlite3PrimaryKeyIndex(index->pTable);
 			int pk_part_count = pPk->def->key_def->part_count;
-			int iKeyReg = sqlite3GetTempRange(pParse, pk_part_count);
+			int iKeyReg = sqlite3GetTempRange(parser, pk_part_count);
 			for (j = 0; j < pk_part_count; j++) {
 				k = pPk->def->key_def->parts[j].fieldno;
 				sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, k,
 						  iKeyReg + j);
 			}
-			sqlite3VdbeAddOp4Int(v, OP_NotFound, iCur, addrCont,
+			sqlite3VdbeAddOp4Int(v, OP_NotFound, cursor, addrCont,
 					     iKeyReg, pk_part_count);
 			VdbeCoverage(v);
-			sqlite3ReleaseTempRange(pParse, iKeyReg, pk_part_count);
+			sqlite3ReleaseTempRange(parser, iKeyReg, pk_part_count);
 		}
 
 		/* Record the instruction used to terminate the loop. */
-		if (pLoop->wsFlags & WHERE_ONEROW) {
-			pLevel->op = OP_Noop;
-		} else if (bRev) {
-			pLevel->op = OP_Prev;
+		if (where_loop->wsFlags & WHERE_ONEROW) {
+			where_level->op = OP_Noop;
+		} else if (is_reversed) {
+			where_level->op = OP_Prev;
 		} else {
-			pLevel->op = OP_Next;
+			where_level->op = OP_Next;
 		}
-		pLevel->p1 = iIdxCur;
-		pLevel->p3 = (pLoop->wsFlags & WHERE_UNQ_WANTED) != 0 ? 1 : 0;
-		if ((pLoop->wsFlags & WHERE_CONSTRAINT) == 0) {
-			pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
+		where_level->p1 = iIdxCur;
+		where_level->p3 =
+			(where_loop->wsFlags & WHERE_UNQ_WANTED) != 0 ? 1 : 0;
+		if ((where_loop->wsFlags & WHERE_CONSTRAINT) == 0) {
+			where_level->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
 		} else {
-			assert(pLevel->p5 == 0);
+			assert(where_level->p5 == 0);
 		}
 	} else
 #ifndef SQLITE_OMIT_OR_OPTIMIZATION
-	if (pLoop->wsFlags & WHERE_MULTI_OR) {
+	if (where_loop->wsFlags & WHERE_MULTI_OR) {
 		/* Case 5:  Two or more separately indexed terms connected by OR
 		 *
 		 * Example:
@@ -1380,56 +1388,59 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 		WhereClause *pOrWc;	/* The OR-clause broken out into subterms */
 		SrcList *pOrTab;	/* Shortened table list or OR-clause generation */
 		Index *pCov = 0;	/* Potential covering index (or NULL) */
-		int iCovCur = pParse->nTab++;	/* Cursor used for index scans (if any) */
+		/* Cursor used for index scans (if any). */
+		int iCovCur = parser->nTab++;
 
-		int regReturn = ++pParse->nMem;	/* Register used with OP_Gosub */
+		/* Register used with OP_Gosub. */
+		int return_reg = ++parser->nMem;
 		int regRowset = 0;	/* Register for RowSet object */
 		int regPk = 0;	/* Register holding PK */
 		int iLoopBody = sqlite3VdbeMakeLabel(v);	/* Start of loop body */
-		int iRetInit;	/* Address of regReturn init */
+		int iRetInit;	/* Address of return_reg init */
 		int untestedTerms = 0;	/* Some terms not completely tested */
 		int ii;		/* Loop counter */
 		u16 wctrlFlags;	/* Flags for sub-WHERE clause */
 		Expr *pAndExpr = 0;	/* An ".. AND (...)" expression */
-		Table *pTab = pTabItem->pTab;
+		Table *pTab = src_list_table->pTab;
 
-		pTerm = pLoop->aLTerm[0];
+		pTerm = where_loop->aLTerm[0];
 		assert(pTerm != 0);
 		assert(pTerm->eOperator & WO_OR);
 		assert((pTerm->wtFlags & TERM_ORINFO) != 0);
 		pOrWc = &pTerm->u.pOrInfo->wc;
-		pLevel->op = OP_Return;
-		pLevel->p1 = regReturn;
+		where_level->op = OP_Return;
+		where_level->p1 = return_reg;
 
 		/* Set up a new SrcList in pOrTab containing the table being scanned
-		 * by this loop in the a[0] slot and all notReady tables in a[1..] slots.
+		 * by this loop in the a[0] slot and all not_ready_mask tables in a[1..] slots.
 		 * This becomes the SrcList in the recursive call to sqlite3WhereBegin().
 		 */
-		if (pWInfo->nLevel > 1) {
-			int nNotReady;	/* The number of notReady tables */
+		if (where_info->nLevel > 1) {
+			int nNotReady;	/* The number of not_ready_mask tables */
 			struct SrcList_item *origSrc;	/* Original list of tables */
-			nNotReady = pWInfo->nLevel - iLevel - 1;
+			nNotReady = where_info->nLevel - level - 1;
 			pOrTab = sqlite3StackAllocRaw(db,
 						      sizeof(*pOrTab) +
 						      nNotReady *
 						      sizeof(pOrTab->a[0]));
 			if (pOrTab == 0)
-				return notReady;
+				return not_ready_mask;
 			pOrTab->nAlloc = (u8) (nNotReady + 1);
 			pOrTab->nSrc = pOrTab->nAlloc;
-			memcpy(pOrTab->a, pTabItem, sizeof(*pTabItem));
-			origSrc = pWInfo->pTabList->a;
+			memcpy(pOrTab->a, src_list_table, sizeof(*src_list_table));
+			origSrc = where_info->pTabList->a;
 			for (k = 1; k <= nNotReady; k++) {
-				memcpy(&pOrTab->a[k], &origSrc[pLevel[k].iFrom],
+				memcpy(&pOrTab->a[k],
+					&origSrc[where_level[k].iFrom],
 				       sizeof(pOrTab->a[k]));
 			}
 		} else {
-			pOrTab = pWInfo->pTabList;
+			pOrTab = where_info->pTabList;
 		}
 
 		/* Create an ephemeral index capable of holding primary keys.
 		 *
-		 * Also initialize regReturn to contain the address of the instruction
+		 * Also initialize return_reg to contain the address of the instruction
 		 * immediately following the OP_Return at the bottom of the loop. This
 		 * is required in a few obscure LEFT JOIN cases where control jumps
 		 * over the top of the loop into the body of it. In this case the
@@ -1437,16 +1448,16 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 		 * fall through to the next instruction, just as an OP_Next does if
 		 * called on an uninitialized cursor.
 		 */
-		if ((pWInfo->wctrlFlags & WHERE_DUPLICATES_OK) == 0) {
+		if ((where_info->wctrlFlags & WHERE_DUPLICATES_OK) == 0) {
 			Index *pPk = sqlite3PrimaryKeyIndex(pTab);
 			int pk_part_count = pPk->def->key_def->part_count;
-			regRowset = pParse->nTab++;
+			regRowset = parser->nTab++;
 			sqlite3VdbeAddOp2(v, OP_OpenTEphemeral,
 					  regRowset, pk_part_count);
-			sql_vdbe_set_p4_key_def(pParse, pPk);
-			regPk = ++pParse->nMem;
+			sql_vdbe_set_p4_key_def(parser, pPk);
+			regPk = ++parser->nMem;
 		}
-		iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, regReturn);
+		iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, return_reg);
 
 		/* If the original WHERE clause is z of the form:  (x1 OR x2 OR ...) AND y
 		 * Then for every term xN, evaluate as the subexpression: xN AND z
@@ -1462,29 +1473,29 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 		 * is not contained in the ON clause of a LEFT JOIN.
 		 * See ticket http://www.sqlite.org/src/info/f2369304e4
 		 */
-		if (pWC->nTerm > 1) {
+		if (where_clause->nTerm > 1) {
 			int iTerm;
-			for (iTerm = 0; iTerm < pWC->nTerm; iTerm++) {
-				Expr *pExpr = pWC->a[iTerm].pExpr;
-				if (&pWC->a[iTerm] == pTerm)
+			for (iTerm = 0; iTerm < where_clause->nTerm; iTerm++) {
+				Expr *pExpr = where_clause->a[iTerm].pExpr;
+				if (&where_clause->a[iTerm] == pTerm)
 					continue;
 				if (ExprHasProperty(pExpr, EP_FromJoin))
 					continue;
-				testcase(pWC->a[iTerm].wtFlags & TERM_VIRTUAL);
-				testcase(pWC->a[iTerm].wtFlags & TERM_CODED);
-				if ((pWC->a[iTerm].
+				testcase(where_clause->a[iTerm].wtFlags & TERM_VIRTUAL);
+				testcase(where_clause->a[iTerm].wtFlags & TERM_CODED);
+				if ((where_clause->a[iTerm].
 				     wtFlags & (TERM_VIRTUAL | TERM_CODED)) !=
 				    0)
 					continue;
-				if ((pWC->a[iTerm].eOperator & WO_ALL) == 0)
+				if ((where_clause->a[iTerm].eOperator & WO_ALL) == 0)
 					continue;
-				testcase(pWC->a[iTerm].wtFlags & TERM_ORINFO);
+				testcase(where_clause->a[iTerm].wtFlags & TERM_ORINFO);
 				pExpr = sqlite3ExprDup(db, pExpr, 0);
 				pAndExpr = sqlite3ExprAnd(db, pAndExpr, pExpr);
 			}
 			if (pAndExpr) {
 				pAndExpr =
-				    sqlite3PExpr(pParse,
+				    sqlite3PExpr(parser,
 						 TK_AND | TKFLG_DONTFOLD, 0,
 						 pAndExpr);
 			}
@@ -1495,11 +1506,11 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 		 * sub-WHERE clause is to to invoke the main loop body as a subroutine.
 		 */
 		wctrlFlags =
-		    WHERE_OR_SUBCLAUSE | (pWInfo->
+		    WHERE_OR_SUBCLAUSE | (where_info->
 					  wctrlFlags & WHERE_SEEK_TABLE);
 		for (ii = 0; ii < pOrWc->nTerm; ii++) {
 			WhereTerm *pOrTerm = &pOrWc->a[ii];
-			if (pOrTerm->leftCursor == iCur
+			if (pOrTerm->leftCursor == cursor
 			    || (pOrTerm->eOperator & WO_AND) != 0) {
 				WhereInfo *pSubWInfo;	/* Info for single OR-term scan */
 				Expr *pOrExpr = pOrTerm->pExpr;	/* Current OR clause term */
@@ -1513,19 +1524,21 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 				WHERETRACE(0xffff,
 					   ("Subplan for OR-clause:\n"));
 				pSubWInfo =
-				    sqlite3WhereBegin(pParse, pOrTab, pOrExpr,
+				    sqlite3WhereBegin(parser, pOrTab, pOrExpr,
 						      0, 0, wctrlFlags,
 						      iCovCur);
-				assert(pSubWInfo || pParse->nErr
+				assert(pSubWInfo || parser->nErr
 				       || db->mallocFailed);
 				if (pSubWInfo) {
 					WhereLoop *pSubLoop;
 					int addrExplain =
-					    sqlite3WhereExplainOneScan(pParse,
+					    sqlite3WhereExplainOneScan(parser,
 								       pOrTab,
-								       &pSubWInfo->a[0],
-								       iLevel,
-								       pLevel->iFrom,
+								       &pSubWInfo->
+								       a[0],
+								       level,
+								       where_level->
+								       iFrom,
 								       0);
 					sqlite3WhereAddScanStatus(v, pOrTab,
 								  &pSubWInfo->a[0],
@@ -1536,7 +1549,7 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 					 * PRIMARY KEY for the current row so that the same
 					 * row will be skipped in subsequent sub-WHERE clauses.
 					 */
-					if ((pWInfo->
+					if ((where_info->
 					     wctrlFlags & WHERE_DUPLICATES_OK)
 					    == 0) {
 						int r;
@@ -1547,7 +1560,7 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 							pPk->def->key_def;
 
 						/* Read the PK into an array of temp registers. */
-						r = sqlite3GetTempRange(pParse,
+						r = sqlite3GetTempRange(parser,
 									def->part_count);
 						for (uint32_t iPk = 0;
 						     iPk < def->part_count;
@@ -1556,10 +1569,10 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 								def->parts[iPk].
 								fieldno;
 							sqlite3ExprCodeGetColumnToReg
-								(pParse,
+								(parser,
 								 pTab->def,
 								 fieldno,
-								 iCur,
+								 cursor,
 								 r + iPk);
 						}
 
@@ -1593,12 +1606,12 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 						}
 
 						/* Release the array of temp registers */
-						sqlite3ReleaseTempRange(pParse, r, def->part_count);
+						sqlite3ReleaseTempRange(parser, r, def->part_count);
 					}
 
 					/* Invoke the main loop body as a subroutine */
 					sqlite3VdbeAddOp2(v, OP_Gosub,
-							  regReturn, iLoopBody);
+							  return_reg, iLoopBody);
 
 					/* Jump here (skipping the main loop body subroutine) if the
 					 * current sub-WHERE row is a duplicate from prior sub-WHEREs.
@@ -1607,8 +1620,8 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 						sqlite3VdbeJumpHere(v, jmp1);
 
 					/* The pSubWInfo->untestedTerms flag means that this OR term
-					 * contained one or more AND term from a notReady table.  The
-					 * terms from the notReady table could not be tested and will
+					 * contained one or more AND term from a not_ready_mask table.  The
+					 * terms from the not_ready_mask table could not be tested and will
 					 * need to be tested later.
 					 */
 					if (pSubWInfo->untestedTerms)
@@ -1643,21 +1656,21 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 				}
 			}
 		}
-		pLevel->u.pCovidx = pCov;
+		where_level->u.pCovidx = pCov;
 		if (pCov)
-			pLevel->iIdxCur = iCovCur;
+			where_level->iIdxCur = iCovCur;
 		if (pAndExpr) {
 			pAndExpr->pLeft = 0;
 			sql_expr_delete(db, pAndExpr, false);
 		}
 		sqlite3VdbeChangeP1(v, iRetInit, sqlite3VdbeCurrentAddr(v));
-		sqlite3VdbeGoto(v, pLevel->addrBrk);
+		sqlite3VdbeGoto(v, where_level->addrBrk);
 		sqlite3VdbeResolveLabel(v, iLoopBody);
 
-		if (pWInfo->nLevel > 1)
+		if (where_info->nLevel > 1)
 			sqlite3StackFree(db, pOrTab);
 		if (!untestedTerms)
-			disableTerm(pLevel, pTerm);
+			disableTerm(where_level, pTerm);
 	} else
 #endif				/* SQLITE_OMIT_OR_OPTIMIZATION */
 
@@ -1667,21 +1680,21 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 		 */
 		static const u8 aStep[] = { OP_Next, OP_Prev };
 		static const u8 aStart[] = { OP_Rewind, OP_Last };
-		assert(bRev == 0 || bRev == 1);
-		if (pTabItem->fg.isRecursive) {
+		assert(is_reversed == 0 || is_reversed == 1);
+		if (src_list_table->fg.isRecursive) {
 			/* Tables marked isRecursive have only a single row that is stored in
 			 * a pseudo-cursor.  No need to Rewind or Next such cursors.
 			 */
-			pLevel->op = OP_Noop;
+			where_level->op = OP_Noop;
 		} else {
-			pLevel->op = aStep[bRev];
-			pLevel->p1 = iCur;
-			pLevel->p2 =
-			    1 + sqlite3VdbeAddOp2(v, aStart[bRev], iCur,
-						  addrBrk);
-			VdbeCoverageIf(v, bRev == 0);
-			VdbeCoverageIf(v, bRev != 0);
-			pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
+			where_level->op = aStep[is_reversed];
+			where_level->p1 = cursor;
+			where_level->p2 =
+			    1 + sqlite3VdbeAddOp2(v, aStart[is_reversed],
+						  cursor, addrBrk);
+			VdbeCoverageIf(v, is_reversed == 0);
+			VdbeCoverageIf(v, is_reversed != 0);
+			where_level->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
 		}
 	}
 
@@ -1692,25 +1705,24 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 	/* Insert code to test every subexpression that can be completely
 	 * computed using the current set of tables.
 	 */
-	for (pTerm = pWC->a, j = pWC->nTerm; j > 0; j--, pTerm++) {
+	for (pTerm = where_clause->a, j = where_clause->nTerm; j > 0;
+	     j--, pTerm++) {
 		Expr *pE;
 		int skipLikeAddr = 0;
 		testcase(pTerm->wtFlags & TERM_VIRTUAL);
 		testcase(pTerm->wtFlags & TERM_CODED);
 		if (pTerm->wtFlags & (TERM_VIRTUAL | TERM_CODED))
 			continue;
-		if ((pTerm->prereqAll & pLevel->notReady) != 0) {
-			testcase(pWInfo->untestedTerms == 0
-				 && (pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE) !=
-				 0);
-			pWInfo->untestedTerms = 1;
+		if ((pTerm->prereq_all_mask &
+		    where_level->not_ready_mask) != 0) {
+			where_info->untestedTerms = 1;
 			continue;
 		}
 		pE = pTerm->pExpr;
 		assert(pE != 0);
-		if (pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin)) {
+		if (where_level->iLeftJoin &&
+		    !ExprHasProperty(pE, EP_FromJoin))
 			continue;
-		}
 		if (pTerm->wtFlags & TERM_LIKECOND) {
 			/* If the TERM_LIKECOND flag is set, that means that the range search
 			 * is sufficient to guarantee that the LIKE operator is true, so we
@@ -1721,7 +1733,7 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 #ifdef SQLITE_LIKE_DOESNT_MATCH_BLOBS
 			continue;
 #else
-			u32 x = pLevel->iLikeRepCntr;
+			u32 x = where_level->iLikeRepCntr;
 			assert(x > 0);
 			skipLikeAddr =
 			    sqlite3VdbeAddOp1(v, (x & 1) ? OP_IfNot : OP_If,
@@ -1729,7 +1741,7 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 			VdbeCoverage(v);
 #endif
 		}
-		sqlite3ExprIfFalse(pParse, pE, addrCont, SQLITE_JUMPIFNULL);
+		sqlite3ExprIfFalse(parser, pE, addrCont, SQLITE_JUMPIFNULL);
 		if (skipLikeAddr)
 			sqlite3VdbeJumpHere(v, skipLikeAddr);
 		pTerm->wtFlags |= TERM_CODED;
@@ -1743,7 +1755,8 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 	 * then we cannot use the "t1.a=t2.b" constraint, but we can code
 	 * the implied "t1.a=123" constraint.
 	 */
-	for (pTerm = pWC->a, j = pWC->nTerm; j > 0; j--, pTerm++) {
+	for (pTerm = where_clause->a, j = where_clause->nTerm; j > 0;
+	     j--, pTerm++) {
 		Expr *pE, sEAlt;
 		WhereTerm *pAlt;
 		if (pTerm->wtFlags & (TERM_VIRTUAL | TERM_CODED))
@@ -1752,16 +1765,17 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 			continue;
 		if ((pTerm->eOperator & WO_EQUIV) == 0)
 			continue;
-		if (pTerm->leftCursor != iCur)
+		if (pTerm->leftCursor != cursor)
 			continue;
-		if (pLevel->iLeftJoin)
+		if (where_level->iLeftJoin)
 			continue;
 		pE = pTerm->pExpr;
 		assert(!ExprHasProperty(pE, EP_FromJoin));
-		assert((pTerm->prereqRight & pLevel->notReady) != 0);
-		pAlt =
-		    sqlite3WhereFindTerm(pWC, iCur, pTerm->u.leftColumn,
-					 notReady, WO_EQ | WO_IN, 0);
+		assert((pTerm->prereq_right_mask &
+			where_level->not_ready_mask) != 0);
+		pAlt = sql_where_find_term(where_clause, cursor,
+					   pTerm->u.leftColumn, not_ready_mask,
+					   WO_EQ | WO_IN, 0);
 		if (pAlt == 0)
 			continue;
 		if (pAlt->wtFlags & (TERM_CODED))
@@ -1771,32 +1785,33 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
 		VdbeModuleComment((v, "begin transitive constraint"));
 		sEAlt = *pAlt->pExpr;
 		sEAlt.pLeft = pE->pLeft;
-		sqlite3ExprIfFalse(pParse, &sEAlt, addrCont, SQLITE_JUMPIFNULL);
+		sqlite3ExprIfFalse(parser, &sEAlt, addrCont, SQLITE_JUMPIFNULL);
 	}
 
 	/* For a LEFT OUTER JOIN, generate code that will record the fact that
 	 * at least one row of the right table has matched the left table.
 	 */
-	if (pLevel->iLeftJoin) {
-		pLevel->addrFirst = sqlite3VdbeCurrentAddr(v);
-		sqlite3VdbeAddOp2(v, OP_Integer, 1, pLevel->iLeftJoin);
+	if (where_level->iLeftJoin != 0) {
+		where_level->addrFirst = sqlite3VdbeCurrentAddr(v);
+		sqlite3VdbeAddOp2(v, OP_Integer, 1, where_level->iLeftJoin);
 		VdbeComment((v, "record LEFT JOIN hit"));
-		sqlite3ExprCacheClear(pParse);
-		for (pTerm = pWC->a, j = 0; j < pWC->nTerm; j++, pTerm++) {
+		sqlite3ExprCacheClear(parser);
+		for (pTerm = where_clause->a, j = 0; j < where_clause->nTerm; j++, pTerm++) {
 			testcase(pTerm->wtFlags & TERM_VIRTUAL);
 			testcase(pTerm->wtFlags & TERM_CODED);
 			if (pTerm->wtFlags & (TERM_VIRTUAL | TERM_CODED))
 				continue;
-			if ((pTerm->prereqAll & pLevel->notReady) != 0) {
-				assert(pWInfo->untestedTerms);
+			if ((pTerm->prereq_all_mask &
+			    where_level->not_ready_mask) != 0) {
+				assert(where_info->untestedTerms);
 				continue;
 			}
 			assert(pTerm->pExpr);
-			sqlite3ExprIfFalse(pParse, pTerm->pExpr, addrCont,
+			sqlite3ExprIfFalse(parser, pTerm->pExpr, addrCont,
 					   SQLITE_JUMPIFNULL);
 			pTerm->wtFlags |= TERM_CODED;
 		}
 	}
 
-	return pLevel->notReady;
+	return where_level->not_ready_mask;
 }
diff --git a/src/box/sql/whereexpr.c b/src/box/sql/whereexpr.c
index 6128686..2b208b1 100644
--- a/src/box/sql/whereexpr.c
+++ b/src/box/sql/whereexpr.c
@@ -126,7 +126,7 @@ whereClauseInsert(WhereClause * pWC, Expr * p, u16 wtFlags)
 
 /*
  * Return TRUE if the given operator is one of the operators that is
- * allowed for an indexable WHERE clause term.  The allowed operators are
+ * allowed for an indexable_mask WHERE clause term.  The allowed operators are
  * "=", "<", ">", "<=", ">=", "IN", "IS", and "IS NULL"
  */
 static int
@@ -481,20 +481,20 @@ whereCombineDisjuncts(SrcList * pSrc,	/* the FROM clause */
  *
  * CASE 3:
  *
- * If all subterms are indexable by a single table T, then set
+ * If all subterms are indexable_mask by a single table T, then set
  *
  *     WhereTerm.eOperator              =  WO_OR
- *     WhereTerm.u.pOrInfo->indexable  |=  the cursor number for table T
+ *     WhereTerm.u.pOrInfo->indexable_mask  |=  the cursor number for table T
  *
- * A subterm is "indexable" if it is of the form
+ * A subterm is "indexable_mask" if it is of the form
  * "T.C <op> <expr>" where C is any column of table T and
  * <op> is one of "=", "<", "<=", ">", ">=", "IS NULL", or "IN".
- * A subterm is also indexable if it is an AND of two or more
- * subsubterms at least one of which is indexable.  Indexable AND
+ * A subterm is also indexable_mask if it is an AND of two or more
+ * subsubterms at least one of which is indexable_mask.  Indexable AND
  * subterms have their eOperator set to WO_AND and they have
  * u.pAndInfo set to a dynamically allocated WhereAndTerm object.
  *
- * From another point of view, "indexable" means that the subterm could
+ * From another point of view, "indexable_mask" means that the subterm could
  * potentially be used with an index if an appropriate index exists.
  * This analysis does not consider whether or not the index exists; that
  * is decided elsewhere.  This analysis only looks at whether subterms
@@ -505,8 +505,8 @@ whereCombineDisjuncts(SrcList * pSrc,	/* the FROM clause */
  * always prefer case 1, so in that case we pretend that case 3 is not
  * satisfied.
  *
- * It might be the case that multiple tables are indexable.  For example,
- * (E) above is indexable on tables P, Q, and R.
+ * It might be the case that multiple tables are indexable_mask.  For example,
+ * (E) above is indexable_mask on tables P, Q, and R.
  *
  * OTHERWISE:
  *
@@ -528,8 +528,6 @@ exprAnalyzeOrTerm(SrcList * pSrc,	/* the FROM clause */
 	WhereClause *pOrWc;	/* Breakup of pTerm into subterms */
 	WhereTerm *pOrTerm;	/* A Sub-term within the pOrWc */
 	WhereOrInfo *pOrInfo;	/* Additional information associated with pTerm */
-	Bitmask chngToIN;	/* Tables that might satisfy case 1 */
-	Bitmask indexable;	/* Tables that are indexable, satisfying case 2 */
 
 	/*
 	 * Break the OR clause into its separate subterms.  The subterms are
@@ -555,21 +553,23 @@ exprAnalyzeOrTerm(SrcList * pSrc,	/* the FROM clause */
 	/*
 	 * Compute the set of tables that might satisfy cases 1 or 3.
 	 */
-	indexable = ~(Bitmask) 0;
-	chngToIN = ~(Bitmask) 0;
-	for (i = pOrWc->nTerm - 1, pOrTerm = pOrWc->a; i >= 0 && indexable;
+	/* Tables that might satisfy case 1. */
+	uint64_t chng_to_in_mask = COLUMN_MASK_FULL;
+	/* Tables that are indexable_mask, satisfying case 2. */
+	uint64_t indexable_mask = COLUMN_MASK_FULL;
+	for (i = pOrWc->nTerm - 1, pOrTerm = pOrWc->a; i >= 0 && indexable_mask;
 	     i--, pOrTerm++) {
 		if ((pOrTerm->eOperator & WO_SINGLE) == 0) {
 			WhereAndInfo *pAndInfo;
 			assert((pOrTerm->
 				wtFlags & (TERM_ANDINFO | TERM_ORINFO)) == 0);
-			chngToIN = 0;
+			chng_to_in_mask = 0;
 			pAndInfo = sqlite3DbMallocRawNN(db, sizeof(*pAndInfo));
 			if (pAndInfo) {
 				WhereClause *pAndWC;
 				WhereTerm *pAndTerm;
 				int j;
-				Bitmask b = 0;
+				uint64_t b = 0;
 				pOrTerm->u.pAndInfo = pAndInfo;
 				pOrTerm->wtFlags |= TERM_ANDINFO;
 				pOrTerm->eOperator = WO_AND;
@@ -581,42 +581,39 @@ exprAnalyzeOrTerm(SrcList * pSrc,	/* the FROM clause */
 						  TK_AND);
 				sqlite3WhereExprAnalyze(pSrc, pAndWC);
 				pAndWC->pOuter = pWC;
-				if (!db->mallocFailed) {
-					for (j = 0, pAndTerm = pAndWC->a;
-					     j < pAndWC->nTerm;
-					     j++, pAndTerm++) {
-						assert(pAndTerm->pExpr);
-						if (allowedOp
-						    (pAndTerm->pExpr->op)
-						    || pAndTerm->eOperator ==
-						    WO_MATCH) {
-							b |= sqlite3WhereGetMask
-							    (&pWInfo->sMaskSet,
-							     pAndTerm->
-							     leftCursor);
-						}
-					}
+				if (db->mallocFailed)
+					break;
+				for (j = 0, pAndTerm = pAndWC->a;
+				     j < pAndWC->nTerm; j++, pAndTerm++) {
+					assert(pAndTerm->pExpr != NULL);
+					if (!allowedOp(pAndTerm->pExpr->op) &&
+					    pAndTerm->eOperator != WO_MATCH)
+						continue;
+					b |= sql_where_get_mask(&pWInfo->
+								sMaskSet,
+								pAndTerm->
+								leftCursor);
 				}
-				indexable &= b;
+				indexable_mask &= b;
 			}
 		} else if (pOrTerm->wtFlags & TERM_COPIED) {
 			/* Skip this term for now.  We revisit it when we process the
 			 * corresponding TERM_VIRTUAL term
 			 */
 		} else {
-			Bitmask b;
-			b = sqlite3WhereGetMask(&pWInfo->sMaskSet,
-						pOrTerm->leftCursor);
+			uint64_t b;
+			b = sql_where_get_mask(&pWInfo->sMaskSet,
+					       pOrTerm->leftCursor);
 			if (pOrTerm->wtFlags & TERM_VIRTUAL) {
 				WhereTerm *pOther = &pOrWc->a[pOrTerm->iParent];
-				b |= sqlite3WhereGetMask(&pWInfo->sMaskSet,
-							 pOther->leftCursor);
+				b |= sql_where_get_mask(&pWInfo->sMaskSet,
+							pOther->leftCursor);
 			}
-			indexable &= b;
+			indexable_mask &= b;
 			if ((pOrTerm->eOperator & WO_EQ) == 0) {
-				chngToIN = 0;
+				chng_to_in_mask = 0;
 			} else {
-				chngToIN &= b;
+				chng_to_in_mask &= b;
 			}
 		}
 	}
@@ -625,12 +622,12 @@ exprAnalyzeOrTerm(SrcList * pSrc,	/* the FROM clause */
 	 * Record the set of tables that satisfy case 3.  The set might be
 	 * empty.
 	 */
-	pOrInfo->indexable = indexable;
-	pTerm->eOperator = indexable == 0 ? 0 : WO_OR;
+	pOrInfo->indexable_mask = indexable_mask;
+	pTerm->eOperator = indexable_mask == 0 ? 0 : WO_OR;
 
 	/* For a two-way OR, attempt to implementation case 2.
 	 */
-	if (indexable && pOrWc->nTerm == 2) {
+	if (indexable_mask && pOrWc->nTerm == 2) {
 		int iOne = 0;
 		WhereTerm *pOne;
 		while ((pOne = whereNthSubterm(&pOrWc->a[0], iOne++)) != 0) {
@@ -644,11 +641,11 @@ exprAnalyzeOrTerm(SrcList * pSrc,	/* the FROM clause */
 	}
 
 	/*
-	 * chngToIN holds a set of tables that *might* satisfy case 1.  But
+	 * chng_to_in_mask holds a set of tables that *might* satisfy case 1.  But
 	 * we have to do some additional checking to see if case 1 really
 	 * is satisfied.
 	 *
-	 * chngToIN will hold either 0, 1, or 2 bits.  The 0-bit case means
+	 * chng_to_in_mask will hold either 0, 1, or 2 bits.  The 0-bit case means
 	 * that there is no possibility of transforming the OR clause into an
 	 * IN operator because one or more terms in the OR clause contain
 	 * something other than == on a column in the single table.  The 1-bit
@@ -664,7 +661,7 @@ exprAnalyzeOrTerm(SrcList * pSrc,	/* the FROM clause */
 	 * Note that terms of the form "table.column1=table.column2" (the
 	 * same table on both sizes of the ==) cannot be optimized.
 	 */
-	if (chngToIN) {
+	if (chng_to_in_mask != 0) {
 		int okToChngToIN = 0;	/* True if the conversion to IN is valid */
 		int iColumn = -1;	/* Column index on lhs of IN operator */
 		int iCursor = -1;	/* Table cursor common to all terms */
@@ -688,14 +685,17 @@ exprAnalyzeOrTerm(SrcList * pSrc,	/* the FROM clause */
 					assert(j == 1);
 					continue;
 				}
-				if ((chngToIN &
-				     sqlite3WhereGetMask(&pWInfo->sMaskSet,
-							 pOrTerm->
-							 leftCursor)) == 0) {
-					/* This term must be of the form t1.a==t2.b where t2 is in the
-					 * chngToIN set but t1 is not.  This term will be either preceded
-					 * or follwed by an inverted copy (t2.b==t1.a).  Skip this term
-					 * and use its inversion.
+				if ((sql_where_get_mask(&pWInfo->sMaskSet,
+							pOrTerm->leftCursor) &
+				     chng_to_in_mask) ==0) {
+					/*
+					 * This term must be of the form
+					 * t1.a==t2.b where t2 is in the
+					 * chng_to_in_mask set but t1 is not.
+					 * This term will be either preceded
+					 * or follwed by an inverted copy
+					 * (t2.b==t1.a).  Skip this term and
+					 * use its inversion.
 					 */
 					testcase(pOrTerm->
 						 wtFlags & TERM_COPIED);
@@ -715,9 +715,9 @@ exprAnalyzeOrTerm(SrcList * pSrc,	/* the FROM clause */
 				 * on the second iteration
 				 */
 				assert(j == 1);
-				assert(IsPowerOfTwo(chngToIN));
-				assert(chngToIN ==
-				       sqlite3WhereGetMask(&pWInfo->sMaskSet,
+				assert(IsPowerOfTwo(chng_to_in_mask));
+				assert(chng_to_in_mask ==
+					sql_where_get_mask(&pWInfo->sMaskSet,
 							   iCursor));
 				break;
 			}
@@ -854,10 +854,10 @@ termIsEquivalence(Parse * pParse, Expr * pExpr)
  * a bitmask indicating which tables are used in that expression
  * tree.
  */
-static Bitmask
+static uint64_t
 exprSelectUsage(WhereMaskSet * pMaskSet, Select * pS)
 {
-	Bitmask mask = 0;
+	uint64_t mask = 0;
 	while (pS) {
 		SrcList *pSrc = pS->pSrc;
 		mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pEList);
@@ -947,9 +947,9 @@ exprAnalyze(SrcList * pSrc,	/* the FROM clause */
 	WhereTerm *pTerm;	/* The term to be analyzed */
 	WhereMaskSet *pMaskSet;	/* Set of table index masks */
 	Expr *pExpr;		/* The expression to be analyzed */
-	Bitmask prereqLeft;	/* Prerequesites of the pExpr->pLeft */
-	Bitmask prereqAll;	/* Prerequesites of pExpr */
-	Bitmask extraRight = 0;	/* Extra dependencies on LEFT JOIN */
+	uint64_t prereqLeft;	/* Prerequesites of the pExpr->pLeft */
+	uint64_t prereqAll;	/* Prerequesites of pExpr */
+	uint64_t extraRight = 0;	/* Extra dependencies on LEFT JOIN */
 	Expr *pStr1 = 0;	/* RHS of LIKE/GLOB operator */
 	int isComplete = 0;	/* RHS of LIKE/GLOB ends with wildcard */
 	int noCase = 0;		/* uppercase equivalent to lowercase */
@@ -971,28 +971,28 @@ exprAnalyze(SrcList * pSrc,	/* the FROM clause */
 		if (sqlite3ExprCheckIN(pParse, pExpr))
 			return;
 		if (ExprHasProperty(pExpr, EP_xIsSelect)) {
-			pTerm->prereqRight =
+			pTerm->prereq_right_mask =
 			    exprSelectUsage(pMaskSet, pExpr->x.pSelect);
 		} else {
-			pTerm->prereqRight =
+			pTerm->prereq_right_mask =
 			    sqlite3WhereExprListUsage(pMaskSet, pExpr->x.pList);
 		}
 	} else if (op == TK_ISNULL) {
-		pTerm->prereqRight = 0;
+		pTerm->prereq_right_mask = 0;
 	} else {
-		pTerm->prereqRight =
+		pTerm->prereq_right_mask =
 		    sqlite3WhereExprUsage(pMaskSet, pExpr->pRight);
 	}
 	prereqAll = sqlite3WhereExprUsage(pMaskSet, pExpr);
 	if (ExprHasProperty(pExpr, EP_FromJoin)) {
-		Bitmask x =
-		    sqlite3WhereGetMask(pMaskSet, pExpr->iRightJoinTable);
+		uint64_t x =
+			sql_where_get_mask(pMaskSet, pExpr->iRightJoinTable);
 		prereqAll |= x;
 		extraRight = x - 1;	/* ON clause terms may not be used with an index
 					 * on left table of a LEFT JOIN.  Ticket #3015
 					 */
 	}
-	pTerm->prereqAll = prereqAll;
+	pTerm->prereq_all_mask = prereqAll;
 	pTerm->leftCursor = -1;
 	pTerm->iParent = -1;
 	pTerm->eOperator = 0;
@@ -1001,7 +1001,7 @@ exprAnalyze(SrcList * pSrc,	/* the FROM clause */
 		Expr *pLeft = sqlite3ExprSkipCollate(pExpr->pLeft);
 		Expr *pRight = sqlite3ExprSkipCollate(pExpr->pRight);
 		u16 opMask =
-		    (pTerm->prereqRight & prereqLeft) == 0 ? WO_ALL : WO_EQUIV;
+		    (pTerm->prereq_right_mask & prereqLeft) == 0 ? WO_ALL : WO_EQUIV;
 
 		if (pTerm->iField > 0) {
 			assert(op == TK_IN);
@@ -1050,8 +1050,8 @@ exprAnalyze(SrcList * pSrc,	/* the FROM clause */
 			pNew->leftCursor = iCur;
 			pNew->u.leftColumn = iColumn;
 			testcase((prereqLeft | extraRight) != prereqLeft);
-			pNew->prereqRight = prereqLeft | extraRight;
-			pNew->prereqAll = prereqAll;
+			pNew->prereq_right_mask = prereqLeft | extraRight;
+			pNew->prereq_all_mask = prereqAll;
 			pNew->eOperator =
 			    (operatorMask(pDup->op) + eExtraOp) & opMask;
 		}
@@ -1277,14 +1277,14 @@ exprAnalyze(SrcList * pSrc,	/* the FROM clause */
 					   TERM_VNULL);
 		if (idxNew) {
 			pNewTerm = &pWC->a[idxNew];
-			pNewTerm->prereqRight = 0;
+			pNewTerm->prereq_right_mask = 0;
 			pNewTerm->leftCursor = pLeft->iTable;
 			pNewTerm->u.leftColumn = pLeft->iColumn;
 			pNewTerm->eOperator = WO_GT;
 			markTermAsChild(pWC, idxNew, idxTerm);
 			pTerm = &pWC->a[idxTerm];
 			pTerm->wtFlags |= TERM_COPIED;
-			pNewTerm->prereqAll = pTerm->prereqAll;
+			pNewTerm->prereq_all_mask = pTerm->prereq_all_mask;
 		}
 	}
 
@@ -1293,7 +1293,7 @@ exprAnalyze(SrcList * pSrc,	/* the FROM clause */
 	 */
 	testcase(pTerm != &pWC->a[idxTerm]);
 	pTerm = &pWC->a[idxTerm];
-	pTerm->prereqRight |= extraRight;
+	pTerm->prereq_right_mask |= extraRight;
 }
 
 /***************************************************************************
@@ -1379,14 +1379,14 @@ sqlite3WhereClauseClear(WhereClause * pWC)
  * a bitmask indicating which tables are used in that expression
  * tree.
  */
-Bitmask
+uint64_t
 sqlite3WhereExprUsage(WhereMaskSet * pMaskSet, Expr * p)
 {
-	Bitmask mask;
+	uint64_t mask;
 	if (p == 0)
 		return 0;
 	if (p->op == TK_COLUMN) {
-		mask = sqlite3WhereGetMask(pMaskSet, p->iTable);
+		mask = sql_where_get_mask(pMaskSet, p->iTable);
 		return mask;
 	}
 	assert(!ExprHasProperty(p, EP_TokenOnly));
@@ -1401,11 +1401,11 @@ sqlite3WhereExprUsage(WhereMaskSet * pMaskSet, Expr * p)
 	return mask;
 }
 
-Bitmask
+uint64_t
 sqlite3WhereExprListUsage(WhereMaskSet * pMaskSet, ExprList * pList)
 {
 	int i;
-	Bitmask mask = 0;
+	uint64_t mask = 0;
 	if (pList) {
 		for (i = 0; i < pList->nExpr; i++) {
 			mask |=
-- 
2.7.4







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