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Overview
| Comment: | Add the experimental SQLITE_DEFAULT_INDEX_SHAPE=1 compile-time option that makes a much more pessimistic guess at the effectiveness of unanalyzed indices. |
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| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | index-shape-1 |
| Files: | files | file ages | folders |
| SHA1: |
d8daaba7dae53c76858ff7d7de695af4 |
| User & Date: | drh 2013-09-02 23:40:47.395 |
Context
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2013-09-02
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| 23:40 | Add the experimental SQLITE_DEFAULT_INDEX_SHAPE=1 compile-time option that makes a much more pessimistic guess at the effectiveness of unanalyzed indices. (Leaf check-in: d8daaba7da user: drh tags: index-shape-1) | |
| 20:22 | Simplify branch coverage testing by interchanging the order of two tests in the whereLoopInsert() function. (check-in: f7079b5365 user: drh tags: trunk) | |
Changes
Changes to src/build.c.
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** how aiRowEst[] should be initialized. The numbers generated here
** are based on typical values found in actual indices.
*/
void sqlite3DefaultRowEst(Index *pIdx){
tRowcnt *a = pIdx->aiRowEst;
int i;
tRowcnt n;
assert( a!=0 );
a[0] = pIdx->pTable->nRowEst;
if( a[0]<10 ) a[0] = 10;
n = 10;
for(i=1; i<=pIdx->nColumn; i++){
a[i] = n;
if( n>5 ) n--;
}
if( pIdx->onError!=OE_None ){
a[pIdx->nColumn] = 1;
}
}
/*
** This routine will drop an existing named index. This routine
** implements the DROP INDEX statement.
*/
void sqlite3DropIndex(Parse *pParse, SrcList *pName, int ifExists){
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** how aiRowEst[] should be initialized. The numbers generated here
** are based on typical values found in actual indices.
*/
void sqlite3DefaultRowEst(Index *pIdx){
tRowcnt *a = pIdx->aiRowEst;
int i;
tRowcnt n;
#if !defined(SQLITE_DEFAULT_INDEX_SHAPE) || SQLITE_DEFAULT_INDEX_SHAPE==0
assert( a!=0 );
a[0] = pIdx->pTable->nRowEst;
if( a[0]<10 ) a[0] = 10;
n = 10;
for(i=1; i<=pIdx->nColumn; i++){
a[i] = n;
if( n>5 ) n--;
}
if( pIdx->onError!=OE_None ){
a[pIdx->nColumn] = 1;
}
#else /* if SQLITE_DEFAULT_INDEX_SHAPE==1 */
tRowcnt x = 1, nMax = pIdx->pTable->nRowEst;
int iLog;
int isUnique = pIdx->onError!=OE_None;
assert( a!=0 );
a[0] = nMax;
n = isUnique ? 1 : 10;
for(iLog=1; n<nMax; iLog++, n<<=1){}
i = pIdx->nColumn;
x <<= iLog/i;
//if( x>10 ) x = 10;
a[i] = n = isUnique ? 1 : 10;
while( i>1 ){
n *= x;
a[--i] = n;
}
#endif
}
/*
** This routine will drop an existing named index. This routine
** implements the DROP INDEX statement.
*/
void sqlite3DropIndex(Parse *pParse, SrcList *pName, int ifExists){
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