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Improve the performance of ANALYZE when SQLITE_ENABLE_STAT4 is defined.

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FossilOrigin-Name: 737a82444065752785c643b1d29ca097c828effb
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dan
2017-02-22 19:27:51 +00:00
parent 6bd166b81e
commit bd1d270ec9
3 changed files with 29 additions and 11 deletions
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24
src/analyze.c
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@@ -290,6 +290,7 @@ struct Stat4Accum {
Stat4Sample *aBest; /* Array of nCol best samples */
int iMin; /* Index in a[] of entry with minimum score */
int nSample; /* Current number of samples */
int nMaxEqZero; /* Max leading 0 in anEq[] for any a[] entry */
int iGet; /* Index of current sample accessed by stat_get() */
Stat4Sample *a; /* Array of mxSample Stat4Sample objects */
sqlite3 *db; /* Database connection, for malloc() */
@@ -551,7 +552,14 @@ static void sampleInsert(Stat4Accum *p, Stat4Sample *pNew, int nEqZero){
Stat4Sample *pSample = 0;
int i;
/* Stat4Accum.nMaxEqZero is set to the maximum number of leading 0
** values in the anEq[] array of any sample in Stat4Accum.a[]. In
** other words, if nMaxEqZero is n, then it is guaranteed that there
** are no samples with Stat4Sample.anEq[m]==0 for (m>=n). */
assert( IsStat4 || nEqZero==0 );
if( nEqZero>p->nMaxEqZero ){
p->nMaxEqZero = nEqZero;
}
#ifdef SQLITE_ENABLE_STAT4
if( pNew->isPSample==0 ){
@@ -651,12 +659,22 @@ static void samplePushPrevious(Stat4Accum *p, int iChng){
}
}
/* Update the anEq[] fields of any samples already collected. */
/* Check that no sample contains an anEq[] entry with an index of
** p->nMaxEqZero or greater set to zero. */
for(i=p->nSample-1; i>=0; i--){
int j;
for(j=iChng; j<p->nCol; j++){
if( p->a[i].anEq[j]==0 ) p->a[i].anEq[j] = p->current.anEq[j];
for(j=p->nMaxEqZero; j<p->nCol; j++) assert( p->a[i].anEq[j]>0 );
}
/* Update the anEq[] fields of any samples already collected. */
if( iChng<p->nMaxEqZero ){
for(i=p->nSample-1; i>=0; i--){
int j;
for(j=iChng; j<p->nCol; j++){
if( p->a[i].anEq[j]==0 ) p->a[i].anEq[j] = p->current.anEq[j];
}
}
p->nMaxEqZero = iChng;
}
#endif