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-rw-r--r--src/select.c74
-rw-r--r--src/sqliteInt.h1
-rw-r--r--src/update.c1
-rw-r--r--src/vdbe.h1
4 files changed, 52 insertions, 25 deletions
diff --git a/src/select.c b/src/select.c
index 886ac336f..8f3e5bb9a 100644
--- a/src/select.c
+++ b/src/select.c
@@ -6855,6 +6855,52 @@ static int sameSrcAlias(SrcItem *p0, SrcList *pSrc){
}
/*
+** Return TRUE (non-zero) if the i-th entry in the pTabList SrcList can
+** be implemented as a co-routine. The i-th entry is guaranteed to be
+** a subquery.
+**
+** The subquery is implemented as a co-routine if all of the following are
+** true:
+**
+** (1) Either of the following are true:
+** (1a) The subquery must be the outer loop because it is either
+** (i) the only term in the FROM clause, or because (ii) it
+** is the left-most term and a CROSS JOIN or similar requires
+** it to be the outer loop. subquery and there is nothing
+** (1b) There is nothing that would prevent the subquery from
+** being an outer loop and the SQLITE_PREPARE_SAFESQL flag
+** is not set.
+** (2) The subquery is not a CTE that should be materialized
+** (3) The subquery is not part of a left operand for a RIGHT JOIN
+** (4) The SQLITE_Coroutine optimization disable flag is not set
+*/
+static int fromClauseTermCanBeCoroutine(
+ Parse *pParse, /* Parsing context */
+ SrcList *pTabList, /* FROM clause */
+ int i /* Which term of the FROM clause */
+){
+ SrcItem *pItem = &pTabList->a[i];
+ if( pItem->fg.isCte && pItem->u2.pCteUse->eM10d==M10d_Yes ) return 0;/* (2) */
+ if( pTabList->a[0].fg.jointype & JT_LTORJ ) return 0; /* (3) */
+ if( OptimizationDisabled(pParse->db, SQLITE_Coroutines) ) return 0; /* (4) */
+ if( i==0 ){
+ if( pTabList->nSrc==1 ) return 1; /* (1a-i) */
+ if( pTabList->a[1].fg.jointype & JT_CROSS ) return 1; /* (1a-ii) */
+ if( pParse->prepFlags & SQLITE_PREPARE_SAFEOPT ) return 0;
+ return 1;
+ }
+ if( pParse->prepFlags & SQLITE_PREPARE_SAFEOPT ) return 0;
+ while( 1 /*exit-by-break*/ ){
+ if( pItem->fg.jointype & (JT_OUTER|JT_CROSS) ) return 0;
+ if( i==0 ) break;
+ i--;
+ pItem--;
+ if( pItem->pSelect!=0 ) return 0;
+ }
+ return 1;
+}
+
+/*
** Generate code for the SELECT statement given in the p argument.
**
** The results are returned according to the SelectDest structure.
@@ -7241,35 +7287,19 @@ int sqlite3Select(
pParse->zAuthContext = pItem->zName;
/* Generate code to implement the subquery
- **
- ** The subquery is implemented as a co-routine if all of the following are
- ** true:
- **
- ** (1) the subquery is guaranteed to be the outer loop (so that
- ** it does not need to be computed more than once), and
- ** (2) the subquery is not a CTE that should be materialized
- ** (3) the subquery is not part of a left operand for a RIGHT JOIN
*/
- if( i==0
- && (pTabList->nSrc==1
- || (pTabList->a[1].fg.jointype&(JT_OUTER|JT_CROSS))!=0) /* (1) */
- && (pItem->fg.isCte==0 || pItem->u2.pCteUse->eM10d!=M10d_Yes) /* (2) */
- && (pTabList->a[0].fg.jointype & JT_LTORJ)==0 /* (3) */
- ){
+ if( fromClauseTermCanBeCoroutine(pParse, pTabList, i) ){
/* Implement a co-routine that will return a single row of the result
** set on each invocation.
*/
int addrTop = sqlite3VdbeCurrentAddr(v)+1;
-#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
- int addrExplain;
-#endif
pItem->regReturn = ++pParse->nMem;
sqlite3VdbeAddOp3(v, OP_InitCoroutine, pItem->regReturn, 0, addrTop);
VdbeComment((v, "%!S", pItem));
pItem->addrFillSub = addrTop;
sqlite3SelectDestInit(&dest, SRT_Coroutine, pItem->regReturn);
- ExplainQueryPlan2(addrExplain, (pParse, 1, "CO-ROUTINE %!S", pItem));
+ ExplainQueryPlan((pParse, 1, "CO-ROUTINE %!S", pItem));
sqlite3Select(pParse, pSub, &dest);
pItem->pTab->nRowLogEst = pSub->nSelectRow;
pItem->fg.viaCoroutine = 1;
@@ -7277,10 +7307,6 @@ int sqlite3Select(
sqlite3VdbeEndCoroutine(v, pItem->regReturn);
sqlite3VdbeJumpHere(v, addrTop-1);
sqlite3ClearTempRegCache(pParse);
- /* For SQLITE_SCANSTAT_NCYCLE, all instructions from the
- ** OP_InitCoroutine coded above until this point are attributed to
- ** the CO-ROUTINE query element. */
- sqlite3VdbeScanStatusRange(v, addrExplain, addrExplain-1, -1);
}else if( pItem->fg.isCte && pItem->u2.pCteUse->addrM9e>0 ){
/* This is a CTE for which materialization code has already been
** generated. Invoke the subroutine to compute the materialization,
@@ -7335,6 +7361,7 @@ int sqlite3Select(
if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr);
sqlite3VdbeAddOp2(v, OP_Return, pItem->regReturn, topAddr+1);
VdbeComment((v, "end %!S", pItem));
+ sqlite3VdbeScanStatusRange(v, addrExplain, addrExplain, -1);
sqlite3VdbeJumpHere(v, topAddr);
sqlite3ClearTempRegCache(pParse);
if( pItem->fg.isCte && pItem->fg.isCorrelated==0 ){
@@ -7344,9 +7371,6 @@ int sqlite3Select(
pCteUse->iCur = pItem->iCursor;
pCteUse->nRowEst = pSub->nSelectRow;
}
- /* For SQLITE_SCANSTAT_NCYCLE, all instructions from the
- ** OP_Explain to here are attibuted to the MATERIALIZE element. */
- sqlite3VdbeScanStatusRange(v, addrExplain, addrExplain, -1);
}
if( db->mallocFailed ) goto select_end;
pParse->nHeight -= sqlite3SelectExprHeight(p);
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 5a19058bd..393237358 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -1844,6 +1844,7 @@ struct sqlite3 {
#define SQLITE_FlttnUnionAll 0x00800000 /* Disable the UNION ALL flattener */
/* TH3 expects this value ^^^^^^^^^^ See flatten04.test */
#define SQLITE_IndexedExpr 0x01000000 /* Pull exprs from index when able */
+#define SQLITE_Coroutines 0x02000000 /* Co-routines for subqueries */
#define SQLITE_AllOpts 0xffffffff /* All optimizations */
/*
diff --git a/src/update.c b/src/update.c
index 809b30653..0612b2708 100644
--- a/src/update.c
+++ b/src/update.c
@@ -268,6 +268,7 @@ static void updateFromSelect(
if( pSelect ) pSelect->selFlags |= SF_OrderByReqd;
sqlite3SelectDestInit(&dest, eDest, iEph);
dest.iSDParm2 = (pPk ? pPk->nKeyCol : -1);
+ pParse->prepFlags |= SQLITE_PREPARE_SAFEOPT;
sqlite3Select(pParse, pSelect, &dest);
sqlite3SelectDelete(db, pSelect);
}
diff --git a/src/vdbe.h b/src/vdbe.h
index 3caf1f787..17a301bd8 100644
--- a/src/vdbe.h
+++ b/src/vdbe.h
@@ -169,6 +169,7 @@ typedef struct VdbeOpList VdbeOpList;
** Additional non-public SQLITE_PREPARE_* flags
*/
#define SQLITE_PREPARE_SAVESQL 0x80 /* Preserve SQL text */
+#define SQLITE_PREPARE_SAFEOPT 0x40 /* Use only safe optimizations */
#define SQLITE_PREPARE_MASK 0x0f /* Mask of public flags */
/*
generated by cgit v1.2.3 (git 2.25.1) at 2025-07-21 23:26:00 +0000