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Experimental change to explain query plan to identify covering indexes on expressions.

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FossilOrigin-Name: 3bb03a2891e30c58b66e3665a8877a8eab4a8bac57ee153d8d31358caeaf4b7c
This commit is contained in:
dan
2024-10-11 20:36:26 +00:00
parent 4859bc9a9f
commit 14101a3c28
7 changed files with 142 additions and 44 deletions
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24
src/where.c
View File

@ -7441,14 +7441,28 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
pOp->p2 = x;
pOp->p1 = pLevel->iIdxCur;
OpcodeRewriteTrace(db, k, pOp);
}else{
/* Unable to translate the table reference into an index
** reference. Verify that this is harmless - that the
** table being referenced really is open.
*/
}else if( pLoop->wsFlags & (WHERE_IDX_ONLY|WHERE_EXPRIDX) ){
if( pLoop->wsFlags & WHERE_IDX_ONLY ){
/* An error. pLoop is supposed to be a covering index loop,
** and yet the VM code refers to a column of the table that
** is not part of the index. */
sqlite3ErrorMsg(pParse, "internal query planner error");
pParse->rc = SQLITE_INTERNAL;
}else{
/* The WHERE_EXPRIDX flag is set by the planner when it is likely
** that pLoop is a covering index loop, but it is not possible
** to be 100% sure. In this case, any OP_Explain opcode
** corresponding to this loop describes the index as a "COVERING
** INDEX". But, pOp proves that pLoop is not actually a covering
** index loop. So clear the WHERE_EXPRIDX flag and rewrite the
** text that accompanies the OP_Explain opcode, if any. */
pLoop->wsFlags &= ~WHERE_EXPRIDX;
sqlite3WhereAddExplainText(pParse,
pLevel->addrBody-1,
pTabList,
pLevel,
pWInfo->wctrlFlags
);
}
}
}else if( pOp->opcode==OP_Rowid ){

8
src/whereInt.h
View File

@ -533,9 +533,17 @@ int sqlite3WhereExplainBloomFilter(
const WhereInfo *pWInfo, /* WHERE clause */
const WhereLevel *pLevel /* Bloom filter on this level */
);
void sqlite3WhereAddExplainText(
Parse *pParse, /* Parse context */
int addr,
SrcList *pTabList, /* Table list this loop refers to */
WhereLevel *pLevel, /* Scan to write OP_Explain opcode for */
u16 wctrlFlags /* Flags passed to sqlite3WhereBegin() */
);
#else
# define sqlite3WhereExplainOneScan(u,v,w,x) 0
# define sqlite3WhereExplainBloomFilter(u,v,w) 0
# define sqlite3WhereAddExplainText(u,v,w,x,y)
#endif /* SQLITE_OMIT_EXPLAIN */
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
void sqlite3WhereAddScanStatus(

65
src/wherecode.c
View File

@ -110,27 +110,24 @@ static void explainIndexRange(StrAccum *pStr, WhereLoop *pLoop){
}
/*
** This function is a no-op unless currently processing an EXPLAIN QUERY PLAN
** command, or if stmt_scanstatus_v2() stats are enabled, or if SQLITE_DEBUG
** was defined at compile-time. If it is not a no-op, a single OP_Explain
** opcode is added to the output to describe the table scan strategy in pLevel.
**
** If an OP_Explain opcode is added to the VM, its address is returned.
** Otherwise, if no OP_Explain is coded, zero is returned.
** This function sets the P4 value of an existing OP_Explain opcode to
** text describing the loop in pLevel. If the OP_Explain opcode already has
** a P4 value, it is freed before it is overwritten.
*/
int sqlite3WhereExplainOneScan(
void sqlite3WhereAddExplainText(
Parse *pParse, /* Parse context */
int addr, /* Address of OP_Explain opcode */
SrcList *pTabList, /* Table list this loop refers to */
WhereLevel *pLevel, /* Scan to write OP_Explain opcode for */
u16 wctrlFlags /* Flags passed to sqlite3WhereBegin() */
){
int ret = 0;
#if !defined(SQLITE_DEBUG)
if( sqlite3ParseToplevel(pParse)->explain==2 || IS_STMT_SCANSTATUS(pParse->db) )
#endif
{
VdbeOp *pOp = sqlite3VdbeGetOp(pParse->pVdbe, addr);
SrcItem *pItem = &pTabList->a[pLevel->iFrom];
Vdbe *v = pParse->pVdbe; /* VM being constructed */
sqlite3 *db = pParse->db; /* Database handle */
int isSearch; /* True for a SEARCH. False for SCAN. */
WhereLoop *pLoop; /* The controlling WhereLoop object */
@ -139,9 +136,10 @@ int sqlite3WhereExplainOneScan(
StrAccum str; /* EQP output string */
char zBuf[100]; /* Initial space for EQP output string */
if( db->mallocFailed ) return;
pLoop = pLevel->pWLoop;
flags = pLoop->wsFlags;
if( (flags&WHERE_MULTI_OR) || (wctrlFlags&WHERE_OR_SUBCLAUSE) ) return 0;
isSearch = (flags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))!=0
|| ((flags&WHERE_VIRTUALTABLE)==0 && (pLoop->u.btree.nEq>0))
@ -165,7 +163,7 @@ int sqlite3WhereExplainOneScan(
zFmt = "AUTOMATIC PARTIAL COVERING INDEX";
}else if( flags & WHERE_AUTO_INDEX ){
zFmt = "AUTOMATIC COVERING INDEX";
}else if( flags & WHERE_IDX_ONLY ){
}else if( flags & (WHERE_IDX_ONLY|WHERE_EXPRIDX) ){
zFmt = "COVERING INDEX %s";
}else{
zFmt = "INDEX %s";
@ -219,9 +217,46 @@ int sqlite3WhereExplainOneScan(
#endif
zMsg = sqlite3StrAccumFinish(&str);
sqlite3ExplainBreakpoint("",zMsg);
ret = sqlite3VdbeAddOp4(v, OP_Explain, sqlite3VdbeCurrentAddr(v),
pParse->addrExplain, pLoop->rRun,
zMsg, P4_DYNAMIC);
assert( pOp->opcode==OP_Explain );
assert( pOp->p4type==P4_DYNAMIC || pOp->p4.z==0 );
sqlite3DbFree(db, pOp->p4.z);
pOp->p4type = P4_DYNAMIC;
pOp->p4.z = sqlite3StrAccumFinish(&str);
}
}
/*
** This function is a no-op unless currently processing an EXPLAIN QUERY PLAN
** command, or if stmt_scanstatus_v2() stats are enabled, or if SQLITE_DEBUG
** was defined at compile-time. If it is not a no-op, a single OP_Explain
** opcode is added to the output to describe the table scan strategy in pLevel.
**
** If an OP_Explain opcode is added to the VM, its address is returned.
** Otherwise, if no OP_Explain is coded, zero is returned.
*/
int sqlite3WhereExplainOneScan(
Parse *pParse, /* Parse context */
SrcList *pTabList, /* Table list this loop refers to */
WhereLevel *pLevel, /* Scan to write OP_Explain opcode for */
u16 wctrlFlags /* Flags passed to sqlite3WhereBegin() */
){
int ret = 0;
#if !defined(SQLITE_DEBUG)
if( sqlite3ParseToplevel(pParse)->explain==2 || IS_STMT_SCANSTATUS(pParse->db) )
#endif
{
if( (pLevel->pWLoop->wsFlags & WHERE_MULTI_OR)==0
&& (wctrlFlags & WHERE_OR_SUBCLAUSE)==0
){
Vdbe *v = pParse->pVdbe;
int addr = sqlite3VdbeCurrentAddr(v);
ret = sqlite3VdbeAddOp3(
v, OP_Explain, addr, pParse->addrExplain, pLevel->pWLoop->rRun
);
sqlite3WhereAddExplainText(pParse, addr, pTabList, pLevel, wctrlFlags);
}
}
return ret;
}