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

[Kirill Shcherbatov <kshcherbatov@tarantool.org>]

Hi! Thank you for your ideas.
I've reworked the 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..56dbbe5 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 is_truncate)
 {
 	struct sqlite3 *db = parse->db;
 	if (parse->nErr || db->mallocFailed)
@@ -185,8 +185,11 @@ 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 (!is_truncate) {
+			sqlite3VdbeAddOp1(v, OP_Clear, space_id);
+		} else {
+			sqlite3VdbeAddOp2(v, OP_Clear, space_id, true);
+		}
 
 		/* Do not start Tarantool's transaction in case of
 		 * truncate optimization. This is workaround until
@@ -195,6 +198,13 @@ sql_table_delete_from(struct Parse *parse, struct SrcList *tab_list,
 		 */
 		parse->initiateTTrans = false;
 	} else {
+		if (is_truncate) {
+			diag_set(ClientError, ER_SQL,
+				 "Specified space could not be truncated.");
+			parse->nErr++;
+			parse->rc = SQL_TARANTOOL_ERROR;
+			goto delete_from_cleanup;
+		}
 		/* Resolve the column names in the WHERE clause. */
 		struct NameContext nc;
 		memset(&nc, 0, sizeof(nc));
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..700f40d 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,false);
+}
+
+/////////////////////////// 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..5eb4825 100644
--- a/src/box/sql/sqliteInt.h
+++ b/src/box/sql/sqliteInt.h
@@ -3703,7 +3703,7 @@ void sqlite3OpenTable(Parse *, int iCur, Table *, int);
  */
 void
 sql_table_delete_from(struct Parse *parse, struct SrcList *tab_list,
-		      struct Expr *where);
+		      struct Expr *where, bool is_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..357beaa 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"
@@ -4566,8 +4567,9 @@ case OP_IdxGE:  {       /* jump */
 	break;
 }
 
-/* Opcode: Clear P1 * * * *
+/* Opcode: Clear P1 P2 * * *
  * Synopsis: space id = P1
+ * If P2 is not 0, use Truncate semantics.
  *
  * Delete all contents of the space, which space id is given
  * in P1 argument. It is worth mentioning, that clearing routine
@@ -4579,7 +4581,13 @@ case OP_Clear: {
 	uint32_t space_id = pOp->p1;
 	struct space *space = space_by_id(space_id);
 	assert(space != NULL);
-	rc = tarantoolSqlite3ClearTable(space);
+	rc = 0;
+	if (pOp->p2 > 0) {
+		if (box_truncate(space_id) != 0)
+			rc = SQL_TARANTOOL_ERROR;
+	} else {
+		rc = tarantoolSqlite3ClearTable(space);
+	}
 	if (rc) goto abort_due_to_error;
 	break;
 }
diff --git a/test/sql/delete.result b/test/sql/delete.result
index c33079c..0ab8c6a 100644
--- a/test/sql/delete.result
+++ b/test/sql/delete.result
@@ -33,6 +33,34 @@ box.sql.execute("SELECT * FROM t1;");
 ---
 - - [2, 4]
 ...
+--
+-- gh-2201: TRUNCATE TABLE operation
+--
+box.sql.execute("TRUNCATE TABLE \"_sql_stat1\";")
+---
+- error: Can't truncate a system space, space '_sql_stat1'
+...
+box.sql.execute("START TRANSACTION")
+---
+...
+box.sql.execute("TRUNCATE TABLE t1;")
+---
+- error: DDL does not support multi-statement transactions
+...
+box.sql.execute("ROLLBACK")
+---
+...
+box.sql.execute("SELECT * FROM t1;")
+---
+- - [2, 4]
+...
+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..afe843b 100644
--- a/test/sql/delete.test.lua
+++ b/test/sql/delete.test.lua
@@ -21,6 +21,19 @@ 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 \"_sql_stat1\";")
+
+box.sql.execute("START TRANSACTION")
+box.sql.execute("TRUNCATE TABLE t1;")
+box.sql.execute("ROLLBACK")
+box.sql.execute("SELECT * FROM t1;")
+
+box.sql.execute("TRUNCATE TABLE t1;")
+box.sql.execute("SELECT * FROM t1;")
+
 -- Cleanup
 box.sql.execute("DROP TABLE t1;");