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Add the SQLITE_DEFAULT_AUTOMATIC_INDEX compile-time option, which if set to

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zero turns automatic indices off by default.  Increase the estimated cost
of an automatic index.  Additional minor refactoring of the automatic
index code.

FossilOrigin-Name: 459b3179023c2c45994ea4acbf34ed5f87cf3c18
This commit is contained in:
drh
2013-06-28 21:12:20 +00:00
parent c0537fe59b
commit 986b38792f
5 changed files with 43 additions and 32 deletions
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42
src/where.c
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@@ -444,7 +444,7 @@ struct WhereInfo {
#define WHERE_IN_ABLE 0x00000800 /* Able to support an IN operator */
#define WHERE_ONEROW 0x00001000 /* Selects no more than one row */
#define WHERE_MULTI_OR 0x00002000 /* OR using multiple indices */
#define WHERE_TEMP_INDEX 0x00004000 /* Uses an ephemeral index */
#define WHERE_AUTO_INDEX 0x00004000 /* Uses an ephemeral index */
/* Convert a WhereCost value (10 times log2(X)) into its integer value X.
@@ -2072,7 +2072,7 @@ static void constructAutomaticIndex(
assert( nColumn>0 );
pLoop->u.btree.nEq = pLoop->nLTerm = nColumn;
pLoop->wsFlags = WHERE_COLUMN_EQ | WHERE_IDX_ONLY | WHERE_INDEXED
| WHERE_TEMP_INDEX;
| WHERE_AUTO_INDEX;
/* Count the number of additional columns needed to create a
** covering index. A "covering index" is an index that contains all
@@ -3118,13 +3118,12 @@ static void explainOneScan(
&& ALWAYS(pLoop->u.btree.pIndex!=0)
){
char *zWhere = explainIndexRange(db, pLoop, pItem->pTab);
zMsg = sqlite3MAppendf(db, zMsg, "%s USING %s%sINDEX%s%s%s", zMsg,
((flags & WHERE_TEMP_INDEX)?"AUTOMATIC ":""),
((flags & WHERE_IDX_ONLY)?"COVERING ":""),
((flags & WHERE_TEMP_INDEX)?"":" "),
((flags & WHERE_TEMP_INDEX)?"": pLoop->u.btree.pIndex->zName),
zWhere
);
zMsg = sqlite3MAppendf(db, zMsg,
((flags & WHERE_AUTO_INDEX) ?
"%s USING AUTOMATIC %sINDEX%.0s%s" :
"%s USING %sINDEX %s%s"),
zMsg, ((flags & WHERE_IDX_ONLY) ? "COVERING " : ""),
pLoop->u.btree.pIndex->zName, zWhere);
sqlite3DbFree(db, zWhere);
}else if( (flags & WHERE_IPK)!=0 && (flags & WHERE_CONSTRAINT)!=0 ){
zMsg = sqlite3MAppendf(db, zMsg, "%s USING INTEGER PRIMARY KEY", zMsg);
@@ -3795,7 +3794,7 @@ static Bitmask codeOneLoopStart(
** be available.
*/
pSubLoop = pSubWInfo->a[0].pWLoop;
assert( (pSubLoop->wsFlags & WHERE_TEMP_INDEX)==0 );
assert( (pSubLoop->wsFlags & WHERE_AUTO_INDEX)==0 );
if( (pSubLoop->wsFlags & WHERE_INDEXED)!=0
&& (ii==0 || pSubLoop->u.btree.pIndex==pCov)
){
@@ -3977,12 +3976,12 @@ static void whereLoopInit(WhereLoop *p){
** Clear the WhereLoop.u union. Leave WhereLoop.pLTerm intact.
*/
static void whereLoopClearUnion(sqlite3 *db, WhereLoop *p){
if( p->wsFlags & (WHERE_VIRTUALTABLE|WHERE_TEMP_INDEX) ){
if( p->wsFlags & (WHERE_VIRTUALTABLE|WHERE_AUTO_INDEX) ){
if( (p->wsFlags & WHERE_VIRTUALTABLE)!=0 && p->u.vtab.needFree ){
sqlite3_free(p->u.vtab.idxStr);
p->u.vtab.needFree = 0;
p->u.vtab.idxStr = 0;
}else if( (p->wsFlags & WHERE_TEMP_INDEX)!=0 && p->u.btree.pIndex!=0 ){
}else if( (p->wsFlags & WHERE_AUTO_INDEX)!=0 && p->u.btree.pIndex!=0 ){
sqlite3DbFree(db, p->u.btree.pIndex->zColAff);
sqlite3DbFree(db, p->u.btree.pIndex);
p->u.btree.pIndex = 0;
@@ -4025,7 +4024,7 @@ static int whereLoopXfer(sqlite3 *db, WhereLoop *pTo, WhereLoop *pFrom){
memcpy(pTo->aLTerm, pFrom->aLTerm, pTo->nLTerm*sizeof(pTo->aLTerm[0]));
if( pFrom->wsFlags & WHERE_VIRTUALTABLE ){
pFrom->u.vtab.needFree = 0;
}else if( (pFrom->wsFlags & WHERE_TEMP_INDEX)!=0 ){
}else if( (pFrom->wsFlags & WHERE_AUTO_INDEX)!=0 ){
pFrom->u.btree.pIndex = 0;
}
return SQLITE_OK;
@@ -4498,13 +4497,16 @@ static int whereLoopAddBtree(
pNew->nLTerm = 1;
pNew->aLTerm[0] = pTerm;
/* TUNING: One-time cost for computing the automatic index is
** approximately 6*N*log2(N) where N is the number of rows in
** approximately 7*N*log2(N) where N is the number of rows in
** the table being indexed. */
pNew->rSetup = rLogSize + rSize + 26; assert( 26==whereCost(6) );
/* TUNING: Each index lookup yields 10 rows in the table */
pNew->nOut = 33; assert( 33==whereCost(10) );
pNew->rSetup = rLogSize + rSize + 28; assert( 28==whereCost(7) );
/* TUNING: Each index lookup yields 20 rows in the table. This
** is more than the usual guess of 10 rows, since we have no way
** of knowning how selective the index will ultimately be. It would
** not be unreasonable to make this value much larger. */
pNew->nOut = 43; assert( 43==whereCost(20) );
pNew->rRun = whereCostAdd(rLogSize,pNew->nOut);
pNew->wsFlags = WHERE_TEMP_INDEX;
pNew->wsFlags = WHERE_AUTO_INDEX;
pNew->prereq = mExtra | pTerm->prereqRight;
rc = whereLoopInsert(pBuilder, pNew);
}
@@ -5881,7 +5883,7 @@ WhereInfo *sqlite3WhereBegin(
sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
}
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
if( (pLoop->wsFlags & WHERE_TEMP_INDEX)!=0 ){
if( (pLoop->wsFlags & WHERE_AUTO_INDEX)!=0 ){
constructAutomaticIndex(pParse, &pWInfo->sWC, pTabItem, notReady, pLevel);
}else
#endif
@@ -6004,7 +6006,7 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
if( !pWInfo->okOnePass && (ws & WHERE_IDX_ONLY)==0 ){
sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor);
}
if( (ws & WHERE_INDEXED)!=0 && (ws & (WHERE_IPK|WHERE_TEMP_INDEX))==0 ){
if( (ws & WHERE_INDEXED)!=0 && (ws & (WHERE_IPK|WHERE_AUTO_INDEX))==0 ){
sqlite3VdbeAddOp1(v, OP_Close, pLevel->iIdxCur);
}
}