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Cache and reuse virtual table index information in the optimizer.

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Improved diagnostics for virtual table index selection. (CVS 3300)

FossilOrigin-Name: 28413cf2b3f0e6f294e1f3c59fcce135b65c294f
This commit is contained in:
drh
2006-06-27 01:54:26 +00:00
parent c1be632489
commit 6d209d8b0d
4 changed files with 101 additions and 37 deletions
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24
src/sqliteInt.h
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@@ -11,7 +11,7 @@
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.514 2006/06/26 21:35:45 drh Exp $
** @(#) $Id: sqliteInt.h,v 1.515 2006/06/27 01:54:26 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_
@@ -1119,6 +1119,19 @@ struct SrcList {
** structure contains a single instance of this structure. This structure
** is intended to be private the the where.c module and should not be
** access or modified by other modules.
**
** The pIdxInfo and pBestIdx fields are used to help pick the best
** index on a virtual table. The pIdxInfo pointer contains indexing
** information for the i-th table in the FROM clause before reordering.
** All the pIdxInfo pointers are freed by whereInfoFree() in where.c.
** The pBestIdx pointer is a copy of pIdxInfo for the i-th table after
** FROM clause ordering. This is a little confusing so I will repeat
** it in different words. WhereInfo.a[i].pIdxInfo is index information
** for WhereInfo.pTabList.a[i]. WhereInfo.a[i].pBestInfo is the
** index information for the i-th loop of the join. pBestInfo is always
** either NULL or a copy of some pIdxInfo. So for cleanup it is
** sufficient to free all of the pIdxInfo pointers.
**
*/
struct WhereLevel {
int iFrom; /* Which entry in the FROM clause */
@@ -1135,7 +1148,13 @@ struct WhereLevel {
int nEq; /* Number of == or IN constraints on this loop */
int nIn; /* Number of IN operators constraining this loop */
int *aInLoop; /* Loop terminators for IN operators */
sqlite3_index_info *pIdxInfo; /* Index information for virtual tables */
sqlite3_index_info *pBestIdx; /* Index information for this level */
/* The following field is really not part of the current level. But
** we need a place to cache index information for each table in the
** FROM clause and the WhereLevel structure is a convenient place.
*/
sqlite3_index_info *pIdxInfo; /* Index info for n-th source table */
};
/*
@@ -1152,6 +1171,7 @@ struct WhereInfo {
int iContinue; /* Jump here to continue with next record */
int iBreak; /* Jump here to break out of the loop */
int nLevel; /* Number of nested loop */
sqlite3_index_info **apInfo; /* Array of pointers to index info structures */
WhereLevel a[1]; /* Information about each nest loop in the WHERE */
};