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More work on the new optimizer. Fewer tests fail now. (CVS 2565)

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FossilOrigin-Name: ee3a08e353f563c36e904479393fcb56f96ee975
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drh
2005-07-27 20:41:43 +00:00
parent 51147baa6d
commit 28c4cf42da
4 changed files with 124 additions and 45 deletions
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46
src/build.c
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@@ -22,7 +22,7 @@
** COMMIT
** ROLLBACK
**
** $Id: build.c,v 1.336 2005/07/23 22:59:56 drh Exp $
** $Id: build.c,v 1.337 2005/07/27 20:41:44 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -2390,15 +2390,47 @@ exit_create_index:
/*
** Fill the Index.aiRowEst[] array with default information - information
** to be used when we have no ANALYZE command to run.
**
** aiRowEst[0] is suppose to contain the number of elements in the index.
** Since we do not know, guess 1 million. aiRowEst[1] is an estimate of the
** number of rows in the table that match any particular value of the
** first column of the index. aiRowEst[2] is an estimate of the number
** of rows that match any particular combiniation of the first 2 columns
** of the index. And so forth. It must always be the case that
*
** aiRowEst[N]<=aiRowEst[N-1]
** aiRowEst[N]>=1
**
** Apart from that, we have little to go on besides intuition as to
** how aiRowEst[] should be initialized. The numbers generated here
** are based on typical values found in actual indices.
*/
void sqlite3DefaultRowEst(Index *pIdx){
int *a = pIdx->aiRowEst;
int i;
int n = pIdx->nColumn;
int j = 1000000;
int f = (1000000-1-100*(pIdx->onError==OE_None))/n;
for(i=0; i<=n; i++, j-=f){
assert( j>0 );
pIdx->aiRowEst[i] = j;
assert( a!=0 );
a[0] = 1000000;
switch( pIdx->nColumn ){
case 1: {
a[1] = 20;
break;
}
case 2: {
a[1] = 350;
a[2] = 20;
break;
}
default: {
a[1] = 1250;
a[2] = 350;
a[3] = 20;
for(i=pIdx->nColumn; i>=4; i--){
a[i] = 10;
}
}
}
if( pIdx->onError!=OE_None ){
a[pIdx->nColumn] = 1;
}
}