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Allow ORDER BY, LIMIT in sub-selects. Fix most (not all) cases where

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the grammar did not allow redundant parentheses around sub-selects.
Distinguish LIMIT ALL from LIMIT 0; make the latter behave as one would
expect.
This commit is contained in:
Tom Lane
2000-11-05 00:15:54 +00:00
parent 66436e66e1
commit 11f7b29054
8 changed files with 400 additions and 230 deletions
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23
src/backend/optimizer/plan/planner.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.93 2000/10/26 21:36:09 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.94 2000/11/05 00:15:53 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -809,25 +809,26 @@ union_planner(Query *parse,
if (IsA(parse->limitCount, Const))
{
Const *limitc = (Const *) parse->limitCount;
int count = (int) (limitc->constvalue);
int32 count = DatumGetInt32(limitc->constvalue);
/*
* The constant can legally be either 0 ("ALL") or a
* positive integer. If it is not ALL, we also need
* to consider the OFFSET part of LIMIT.
* A NULL-constant LIMIT represents "LIMIT ALL",
* which we treat the same as no limit (ie,
* expect to retrieve all the tuples).
*/
if (count > 0)
if (!limitc->constisnull && count > 0)
{
tuple_fraction = (double) count;
/* We must also consider the OFFSET, if present */
if (parse->limitOffset != NULL)
{
if (IsA(parse->limitOffset, Const))
{
int offset;
int32 offset;
limitc = (Const *) parse->limitOffset;
offset = (int) (limitc->constvalue);
if (offset > 0)
offset = DatumGetInt32(limitc->constvalue);
if (!limitc->constisnull && offset > 0)
tuple_fraction += (double) offset;
}
else
@ -850,14 +851,14 @@ union_planner(Query *parse,
}
/*
* Check for a retrieve-into-portal, ie DECLARE CURSOR.
* If no LIMIT, check for retrieve-into-portal, ie DECLARE CURSOR.
*
* We have no real idea how many tuples the user will ultimately
* FETCH from a cursor, but it seems a good bet that he
* doesn't want 'em all. Optimize for 10% retrieval (you
* gotta better number?)
*/
if (parse->isPortal)
else if (parse->isPortal)
tuple_fraction = 0.10;
}