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Minor optimizations for sub-selects in EXISTS(...) expressions: Discard any DISTINCT or ORDER BY clauses and do not calculate any column values. (CVS 4658)

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FossilOrigin-Name: fbd17a8976cc9b4dd7c7c903d8beade9a7ef095f
This commit is contained in:
danielk1977
2008-01-02 17:11:14 +00:00
parent 6c8c8ce0e2
commit 9ed1dfa802
4 changed files with 29 additions and 19 deletions
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18
src/sqliteInt.h
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@@ -11,7 +11,7 @@
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.629 2008/01/02 16:27:10 danielk1977 Exp $
** @(#) $Id: sqliteInt.h,v 1.630 2008/01/02 17:11:14 danielk1977 Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_
@@ -1330,18 +1330,18 @@ struct Select {
*/
#define SRT_Union 1 /* Store result as keys in an index */
#define SRT_Except 2 /* Remove result from a UNION index */
#define SRT_Discard 3 /* Do not save the results anywhere */
#define SRT_Exists 3 /* Store 1 if the result is not empty */
#define SRT_Discard 4 /* Do not save the results anywhere */
/* The ORDER BY clause is ignored for all of the above */
#define IgnorableOrderby(X) ((X->eDest)<=SRT_Discard)
#define SRT_Callback 4 /* Invoke a callback with each row of result */
#define SRT_Mem 5 /* Store result in a memory cell */
#define SRT_Set 6 /* Store non-null results as keys in an index */
#define SRT_Table 7 /* Store result as data with an automatic rowid */
#define SRT_EphemTab 8 /* Create transient tab and store like SRT_Table */
#define SRT_Subroutine 9 /* Call a subroutine to handle results */
#define SRT_Exists 10 /* Store 1 if the result is not empty */
#define SRT_Callback 5 /* Invoke a callback with each row of result */
#define SRT_Mem 6 /* Store result in a memory cell */
#define SRT_Set 7 /* Store non-null results as keys in an index */
#define SRT_Table 8 /* Store result as data with an automatic rowid */
#define SRT_EphemTab 9 /* Create transient tab and store like SRT_Table */
#define SRT_Subroutine 10 /* Call a subroutine to handle results */
/*
** A structure used to customize the behaviour of sqlite3Select(). See