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When materializing a view for an UPDATE or DELETE make use of the WHERE

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clause to limit the number of rows materialized.  Ticket #2938. (CVS 4782)

FossilOrigin-Name: 5ab71c3a79cac04cb2c576f83a62218d05571006
This commit is contained in:
drh
2008-02-12 16:52:14 +00:00
parent 8e5b5f8e54
commit 0f35a6b529
7 changed files with 305 additions and 46 deletions
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59
src/delete.c
View File

@@ -12,7 +12,7 @@
** This file contains C code routines that are called by the parser
** in order to generate code for DELETE FROM statements.
**
** $Id: delete.c,v 1.160 2008/01/25 15:04:50 drh Exp $
** $Id: delete.c,v 1.161 2008/02/12 16:52:14 drh Exp $
*/
#include "sqliteInt.h"
@@ -81,6 +81,39 @@ void sqlite3OpenTable(
}
#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
/*
** Evaluate a view and store its result in an ephemeral table. The
** pWhere argument is an optional WHERE clause that restricts the
** set of rows in the view that are to be added to the ephemeral table.
*/
void sqlite3MaterializeView(
Parse *pParse, /* Parsing context */
Select *pView, /* View definition */
Expr *pWhere, /* Optional WHERE clause to be added */
u32 col_mask, /* Render only the columns in this mask. */
int iCur /* Cursor number for ephemerial table */
){
SelectDest dest;
Select *pDup;
sqlite3 *db = pParse->db;
pDup = sqlite3SelectDup(db, pView);
if( pWhere ){
SrcList *pFrom;
pWhere = sqlite3ExprDup(db, pWhere);
pFrom = sqlite3SrcListAppendFromTerm(pParse, 0, 0, 0, 0, pDup, 0, 0);
pDup = sqlite3SelectNew(pParse, 0, pFrom, pWhere, 0, 0, 0, 0, 0, 0);
}
sqlite3SelectMask(pParse, pDup, col_mask);
sqlite3SelectDestInit(&dest, SRT_EphemTab, iCur);
sqlite3Select(pParse, pDup, &dest, 0, 0, 0, 0);
sqlite3SelectDelete(pDup);
}
#endif /* !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER) */
/*
** Generate code for a DELETE FROM statement.
**
@@ -170,19 +203,13 @@ void sqlite3DeleteFrom(
oldIdx = pParse->nTab++;
}
/* Resolve the column names in the WHERE clause.
/* Assign cursor number to the table and all its indices.
*/
assert( pTabList->nSrc==1 );
iCur = pTabList->a[0].iCursor = pParse->nTab++;
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
pParse->nTab++;
}
memset(&sNC, 0, sizeof(sNC));
sNC.pParse = pParse;
sNC.pSrcList = pTabList;
if( sqlite3ExprResolveNames(&sNC, pWhere) ){
goto delete_from_cleanup;
}
/* Start the view context
*/
@@ -221,14 +248,16 @@ void sqlite3DeleteFrom(
** a ephemeral table.
*/
if( isView ){
SelectDest dest;
Select *pView;
sqlite3MaterializeView(pParse, pTab->pSelect, pWhere, old_col_mask, iCur);
}
pView = sqlite3SelectDup(db, pTab->pSelect);
sqlite3SelectMask(pParse, pView, old_col_mask);
sqlite3SelectDestInit(&dest, SRT_EphemTab, iCur);
sqlite3Select(pParse, pView, &dest, 0, 0, 0, 0);
sqlite3SelectDelete(pView);
/* Resolve the column names in the WHERE clause.
*/
memset(&sNC, 0, sizeof(sNC));
sNC.pParse = pParse;
sNC.pSrcList = pTabList;
if( sqlite3ExprResolveNames(&sNC, pWhere) ){
goto delete_from_cleanup;
}
/* Initialize the counter of the number of rows deleted, if