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Remove some unnecessary computations from ANALYZE so that ANALYZE runs with

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fewer CPU cycles.  These changes were spotted while working on the nearby
enhanced-stat1 branch.  So even if enhanced-stat1 is abandoned, that effort
put into it will not have been in vain.

FossilOrigin-Name: 5527e8c4abb904b1a438ec1c353d4a960bf82faaf3a2c742af1df7c613850441
This commit is contained in:
drh
2024-01-01 17:58:57 +00:00
parent 4ccf707c6e
commit 4cfc19f34c
3 changed files with 18 additions and 15 deletions
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src/analyze.c
+11 -5
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@@ -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);
#ifdef SQLITE_ENABLE_STAT4
assert( p->current.anEq[i] );
#endif
}
sqlite3ResultStrAccum(context, &sStat);
}