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Diffstat (limited to 'src/analyze.c')
-rw-r--r--src/analyze.c100
1 files changed, 64 insertions, 36 deletions
diff --git a/src/analyze.c b/src/analyze.c
index a7a8b6d66..e7c1068ae 100644
--- a/src/analyze.c
+++ b/src/analyze.c
@@ -264,9 +264,9 @@ static void openStatTable(
typedef struct StatAccum StatAccum;
typedef struct StatSample StatSample;
struct StatSample {
- tRowcnt *anEq; /* sqlite_stat4.nEq */
tRowcnt *anDLt; /* sqlite_stat4.nDLt */
#ifdef SQLITE_ENABLE_STAT4
+ tRowcnt *anEq; /* sqlite_stat4.nEq */
tRowcnt *anLt; /* sqlite_stat4.nLt */
union {
i64 iRowid; /* Rowid in main table of the key */
@@ -424,9 +424,9 @@ static void statInit(
/* Allocate the space required for the StatAccum object */
n = sizeof(*p)
- + sizeof(tRowcnt)*nColUp /* StatAccum.anEq */
- + sizeof(tRowcnt)*nColUp; /* StatAccum.anDLt */
+ + sizeof(tRowcnt)*nColUp; /* StatAccum.anDLt */
#ifdef SQLITE_ENABLE_STAT4
+ n += sizeof(tRowcnt)*nColUp; /* StatAccum.anEq */
if( mxSample ){
n += sizeof(tRowcnt)*nColUp /* StatAccum.anLt */
+ sizeof(StatSample)*(nCol+mxSample) /* StatAccum.aBest[], a[] */
@@ -447,9 +447,9 @@ static void statInit(
p->nKeyCol = nKeyCol;
p->nSkipAhead = 0;
p->current.anDLt = (tRowcnt*)&p[1];
- p->current.anEq = &p->current.anDLt[nColUp];
#ifdef SQLITE_ENABLE_STAT4
+ p->current.anEq = &p->current.anDLt[nColUp];
p->mxSample = p->nLimit==0 ? mxSample : 0;
if( mxSample ){
u8 *pSpace; /* Allocated space not yet assigned */
@@ -716,7 +716,9 @@ static void statPush(
if( p->nRow==0 ){
/* This is the first call to this function. Do initialization. */
+#ifdef SQLITE_ENABLE_STAT4
for(i=0; i<p->nCol; i++) p->current.anEq[i] = 1;
+#endif
}else{
/* Second and subsequent calls get processed here */
#ifdef SQLITE_ENABLE_STAT4
@@ -725,15 +727,17 @@ static void statPush(
/* Update anDLt[], anLt[] and anEq[] to reflect the values that apply
** to the current row of the index. */
+#ifdef SQLITE_ENABLE_STAT4
for(i=0; i<iChng; i++){
p->current.anEq[i]++;
}
+#endif
for(i=iChng; i<p->nCol; i++){
p->current.anDLt[i]++;
#ifdef SQLITE_ENABLE_STAT4
if( p->mxSample ) p->current.anLt[i] += p->current.anEq[i];
-#endif
p->current.anEq[i] = 1;
+#endif
}
}
@@ -867,7 +871,9 @@ static void statGet(
u64 iVal = (p->nRow + nDistinct - 1) / nDistinct;
if( iVal==2 && p->nRow*10 <= nDistinct*11 ) iVal = 1;
sqlite3_str_appendf(&sStat, " %llu", iVal);
- assert( p->current.anEq[i] );
+#ifdef SQLITE_ENABLE_STAT4
+ assert( p->current.anEq[i] || p->nRow==0 );
+#endif
}
sqlite3ResultStrAccum(context, &sStat);
}
@@ -1051,7 +1057,7 @@ static void analyzeOneTable(
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
int nCol; /* Number of columns in pIdx. "N" */
- int addrRewind; /* Address of "OP_Rewind iIdxCur" */
+ int addrGotoEnd; /* Address of "OP_Rewind iIdxCur" */
int addrNextRow; /* Address of "next_row:" */
const char *zIdxName; /* Name of the index */
int nColTest; /* Number of columns to test for changes */
@@ -1075,9 +1081,14 @@ static void analyzeOneTable(
/*
** Pseudo-code for loop that calls stat_push():
**
- ** Rewind csr
- ** if eof(csr) goto end_of_scan;
** regChng = 0
+ ** Rewind csr
+ ** if eof(csr){
+ ** stat_init() with count = 0;
+ ** goto end_of_scan;
+ ** }
+ ** count()
+ ** stat_init()
** goto chng_addr_0;
**
** next_row:
@@ -1116,41 +1127,36 @@ static void analyzeOneTable(
sqlite3VdbeSetP4KeyInfo(pParse, pIdx);
VdbeComment((v, "%s", pIdx->zName));
- /* Invoke the stat_init() function. The arguments are:
- **
+ /* Implementation of the following:
+ **
+ ** regChng = 0
+ ** Rewind csr
+ ** if eof(csr){
+ ** stat_init() with count = 0;
+ ** goto end_of_scan;
+ ** }
+ ** count()
+ ** stat_init()
+ ** goto chng_addr_0;
+ */
+ assert( regTemp2==regStat+4 );
+ sqlite3VdbeAddOp2(v, OP_Integer, db->nAnalysisLimit, regTemp2);
+
+ /* Arguments to stat_init():
** (1) the number of columns in the index including the rowid
** (or for a WITHOUT ROWID table, the number of PK columns),
** (2) the number of columns in the key without the rowid/pk
- ** (3) estimated number of rows in the index,
- */
+ ** (3) estimated number of rows in the index. */
sqlite3VdbeAddOp2(v, OP_Integer, nCol, regStat+1);
assert( regRowid==regStat+2 );
sqlite3VdbeAddOp2(v, OP_Integer, pIdx->nKeyCol, regRowid);
-#ifdef SQLITE_ENABLE_STAT4
- if( OptimizationEnabled(db, SQLITE_Stat4) ){
- sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regTemp);
- addrRewind = sqlite3VdbeAddOp1(v, OP_Rewind, iIdxCur);
- VdbeCoverage(v);
- }else
-#endif
- {
- addrRewind = sqlite3VdbeAddOp1(v, OP_Rewind, iIdxCur);
- VdbeCoverage(v);
- sqlite3VdbeAddOp3(v, OP_Count, iIdxCur, regTemp, 1);
- }
- assert( regTemp2==regStat+4 );
- sqlite3VdbeAddOp2(v, OP_Integer, db->nAnalysisLimit, regTemp2);
+ sqlite3VdbeAddOp3(v, OP_Count, iIdxCur, regTemp,
+ OptimizationDisabled(db, SQLITE_Stat4));
sqlite3VdbeAddFunctionCall(pParse, 0, regStat+1, regStat, 4,
&statInitFuncdef, 0);
+ addrGotoEnd = sqlite3VdbeAddOp1(v, OP_Rewind, iIdxCur);
+ VdbeCoverage(v);
- /* Implementation of the following:
- **
- ** Rewind csr
- ** if eof(csr) goto end_of_scan;
- ** regChng = 0
- ** goto next_push_0;
- **
- */
sqlite3VdbeAddOp2(v, OP_Integer, 0, regChng);
addrNextRow = sqlite3VdbeCurrentAddr(v);
@@ -1257,6 +1263,12 @@ static void analyzeOneTable(
}
/* Add the entry to the stat1 table. */
+ if( pIdx->pPartIdxWhere ){
+ /* Partial indexes might get a zero-entry in sqlite_stat1. But
+ ** an empty table is omitted from sqlite_stat1. */
+ sqlite3VdbeJumpHere(v, addrGotoEnd);
+ addrGotoEnd = 0;
+ }
callStatGet(pParse, regStat, STAT_GET_STAT1, regStat1);
assert( "BBB"[0]==SQLITE_AFF_TEXT );
sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regTemp, "BBB", 0);
@@ -1280,6 +1292,12 @@ static void analyzeOneTable(
int addrIsNull;
u8 seekOp = HasRowid(pTab) ? OP_NotExists : OP_NotFound;
+ /* No STAT4 data is generated if the number of rows is zero */
+ if( addrGotoEnd==0 ){
+ sqlite3VdbeAddOp2(v, OP_Cast, regStat1, SQLITE_AFF_INTEGER);
+ addrGotoEnd = sqlite3VdbeAddOp1(v, OP_IfNot, regStat1);
+ }
+
if( doOnce ){
int mxCol = nCol;
Index *pX;
@@ -1332,7 +1350,7 @@ static void analyzeOneTable(
#endif /* SQLITE_ENABLE_STAT4 */
/* End of analysis */
- sqlite3VdbeJumpHere(v, addrRewind);
+ if( addrGotoEnd ) sqlite3VdbeJumpHere(v, addrGotoEnd);
}
@@ -1556,6 +1574,16 @@ static void decodeIntArray(
while( z[0]!=0 && z[0]!=' ' ) z++;
while( z[0]==' ' ) z++;
}
+
+ /* Set the bLowQual flag if the peak number of rows obtained
+ ** from a full equality match is so large that a full table scan
+ ** seems likely to be faster than using the index.
+ */
+ if( aLog[0] > 66 /* Index has more than 100 rows */
+ && aLog[0] <= aLog[nOut-1] /* And only a single value seen */
+ ){
+ pIndex->bLowQual = 1;
+ }
}
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-07-22 08:53:08 +0000