[tarantool-patches] Re: [PATCH v1 1/1] sql: introduce TRUNCATE TABLE operation

[Kirill Shcherbatov <kshcherbatov@tarantool.org>]

> Hello. I do not see, where do you call box_truncate, and where is a
> test that it is called.
I've discussed this problem with Nikita and we have decided to make separate OP_Truncate code.

=====================================

diff --git a/extra/mkkeywordhash.c b/extra/mkkeywordhash.c
index 1ec1538..705caf1 100644
--- a/extra/mkkeywordhash.c
+++ b/extra/mkkeywordhash.c
@@ -281,6 +281,7 @@ static Keyword aKeywordTable[] = {
   { "VARCHAR",                "TK_ID",          RESERVED,         true  },
   { "WHENEVER",               "TK_STANDARD",    RESERVED,         true  },
   { "WHILE",                  "TK_STANDARD",    RESERVED,         true  },
+  { "TRUNCATE",               "TK_TRUNCATE",    ALWAYS,           true  },
 };
 
 /* Number of keywords */
diff --git a/src/box/sql/build.c b/src/box/sql/build.c
index a64d723..be4c860 100644
--- a/src/box/sql/build.c
+++ b/src/box/sql/build.c
@@ -1953,7 +1953,7 @@ vdbe_emit_stat_space_clear(struct Parse *parse, const char *stat_table_name,
 	 * On memory allocation error sql_table delete_from
 	 * releases memory for its own.
 	 */
-	sql_table_delete_from(parse, src_list, where);
+	sql_table_delete_from(parse, src_list, where, false);
 }
 
 /**
diff --git a/src/box/sql/delete.c b/src/box/sql/delete.c
index f9d3498..ab6771d 100644
--- a/src/box/sql/delete.c
+++ b/src/box/sql/delete.c
@@ -73,7 +73,7 @@ sql_materialize_view(struct Parse *parse, const char *name, struct Expr *where,
 
 void
 sql_table_delete_from(struct Parse *parse, struct SrcList *tab_list,
-		      struct Expr *where)
+		      struct Expr *where, bool allow_truncate)
 {
 	struct sqlite3 *db = parse->db;
 	if (parse->nErr || db->mallocFailed)
@@ -185,9 +185,10 @@ sql_table_delete_from(struct Parse *parse, struct SrcList *tab_list,
 	 */
 	if (where == NULL && !is_complex) {
 		assert(!is_view);
-
-		sqlite3VdbeAddOp1(v, OP_Clear, space_id);
-
+		if (!allow_truncate || space_is_system(space) || in_txn() != NULL)
+			sqlite3VdbeAddOp1(v, OP_Clear, space_id);
+		else
+			sqlite3VdbeAddOp1(v, OP_Truncate, space_id);
 		/* Do not start Tarantool's transaction in case of
 		 * truncate optimization. This is workaround until
 		 * system tables cannot be changes inside a
diff --git a/src/box/sql/fkey.c b/src/box/sql/fkey.c
index 6a91890..e67866c 100644
--- a/src/box/sql/fkey.c
+++ b/src/box/sql/fkey.c
@@ -784,7 +784,7 @@ sqlite3FkDropTable(Parse *parser, SrcList *name, Table *table)
 	/* Staring new transaction before DELETE FROM <tbl> */
 	sqlite3VdbeAddOp0(v, OP_TTransaction);
 	sql_table_delete_from(parser, sqlite3SrcListDup(parser->db, name, 0),
-			      NULL);
+			      NULL, false);
 	parser->disableTriggers = 0;
 	/*
 	 * If the DELETE has generated immediate foreign key
diff --git a/src/box/sql/parse.y b/src/box/sql/parse.y
index 0c510f5..18ca39b 100644
--- a/src/box/sql/parse.y
+++ b/src/box/sql/parse.y
@@ -722,7 +722,16 @@ cmd ::= with(C) DELETE FROM fullname(X) indexed_opt(I) where_opt(W). {
   sqlSubProgramsRemaining = SQL_MAX_COMPILING_TRIGGERS;
   /* Instruct SQL to initate Tarantool's transaction.  */
   pParse->initiateTTrans = true;
-  sql_table_delete_from(pParse,X,W);
+  sql_table_delete_from(pParse,X,W,true);
+}
+
+/////////////////////////// The TRUNCATE statement /////////////////////////////
+//
+cmd ::= TRUNCATE TABLE fullname(X). {
+  sqlSubProgramsRemaining = SQL_MAX_COMPILING_TRIGGERS;
+  /* Instruct SQL to initate Tarantool's transaction.  */
+  pParse->initiateTTrans = true;
+  sql_table_delete_from(pParse, X, NULL,true);
 }
 
 %type where_opt {Expr*}
diff --git a/src/box/sql/sqliteInt.h b/src/box/sql/sqliteInt.h
index 54661cb..5c293bc 100644
--- a/src/box/sql/sqliteInt.h
+++ b/src/box/sql/sqliteInt.h
@@ -3700,10 +3700,11 @@ void sqlite3OpenTable(Parse *, int iCur, Table *, int);
  * @param tab_list List of single element which table from which
  * deletetion if performed.
  * @param where The WHERE clause.  May be NULL.
+ * @param allow_truncate use truncate opcode if possible.
  */
 void
 sql_table_delete_from(struct Parse *parse, struct SrcList *tab_list,
-		      struct Expr *where);
+		      struct Expr *where, bool allow_truncate);
 
 void sqlite3Update(Parse *, SrcList *, ExprList *, Expr *,
 		   enum on_conflict_action);
diff --git a/src/box/sql/trigger.c b/src/box/sql/trigger.c
index ec0bc98..1949fdb 100644
--- a/src/box/sql/trigger.c
+++ b/src/box/sql/trigger.c
@@ -698,8 +698,8 @@ codeTriggerProgram(Parse * pParse,	/* The parser context */
 						      targetSrcList(pParse, pStep),
 						      sqlite3ExprDup(db,
 								     pStep->pWhere,
-								     0)
-				    );
+								     0),
+						      false);
 				break;
 			}
 		default:
diff --git a/src/box/sql/vdbe.c b/src/box/sql/vdbe.c
index f50e389..66a567b 100644
--- a/src/box/sql/vdbe.c
+++ b/src/box/sql/vdbe.c
@@ -39,6 +39,7 @@
  * in this file for details.  If in doubt, do not deviate from existing
  * commenting and indentation practices when changing or adding code.
  */
+#include "box/box.h"
 #include "box/txn.h"
 #include "box/session.h"
 #include "sqliteInt.h"
@@ -4574,12 +4575,27 @@ case OP_IdxGE:  {       /* jump */
  * doesn't involve truncating, since it features completely
  * different mechanism under hood.
  */
-case OP_Clear: {
+/* Opcode: Truncate P1 * * * *
+ * Synopsis: space id = P1
+ *
+ * Same as OP_Clear except this routine uses box_truncate that
+ * works faster, but have some restictions: the space_id is not an
+ * ID of system space, this routine mustn't be called by active
+ * transaction.
+ */
+case OP_Clear:
+case OP_Truncate: {
 	assert(pOp->p1 > 0);
 	uint32_t space_id = pOp->p1;
-	struct space *space = space_by_id(space_id);
-	assert(space != NULL);
-	rc = tarantoolSqlite3ClearTable(space);
+	if (pOp->opcode == OP_Clear) {
+		struct space *space = space_by_id(space_id);
+		assert(space != NULL);
+		rc = tarantoolSqlite3ClearTable(space);
+	} else {
+		rc = box_truncate(space_id);
+		if (rc != 0)
+			rc = SQL_TARANTOOL_ERROR;
+	}
 	if (rc) goto abort_due_to_error;
 	break;
 }
diff --git a/test/sql/delete.result b/test/sql/delete.result
index c33079c..6026406 100644
--- a/test/sql/delete.result
+++ b/test/sql/delete.result
@@ -33,6 +33,16 @@ box.sql.execute("SELECT * FROM t1;");
 ---
 - - [2, 4]
 ...
+--
+-- gh-2201: TRUNCATE TABLE operation
+--
+box.sql.execute("TRUNCATE TABLE t1;")
+---
+...
+box.sql.execute("SELECT * FROM t1;")
+---
+- []
+...
 -- Cleanup
 box.sql.execute("DROP TABLE t1;");
 ---
diff --git a/test/sql/delete.test.lua b/test/sql/delete.test.lua
index 1721989..7132302 100644
--- a/test/sql/delete.test.lua
+++ b/test/sql/delete.test.lua
@@ -21,6 +21,12 @@ box.sql.execute("DELETE FROM t1 WHERE a=1;");
 -- Verify
 box.sql.execute("SELECT * FROM t1;");
 
+--
+-- gh-2201: TRUNCATE TABLE operation
+--
+box.sql.execute("TRUNCATE TABLE t1;")
+box.sql.execute("SELECT * FROM t1;")
+
 -- Cleanup
 box.sql.execute("DROP TABLE t1;");