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Support window functions a la SQL:2008.

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Hitoshi Harada, with some kibitzing from Heikki and Tom.
This commit is contained in:
Tom Lane
2008-12-28 18:54:01 +00:00
parent 38e9348282
commit 95b07bc7f5
92 changed files with 6720 additions and 321 deletions
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19
src/backend/optimizer/path/allpaths.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.177 2008/11/15 19:43:46 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.178 2008/12/28 18:53:56 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -929,10 +929,13 @@ standard_join_search(PlannerInfo *root, int levels_needed, List *initial_rels)
* 1. If the subquery has a LIMIT clause, we must not push down any quals,
* since that could change the set of rows returned.
*
* 2. If the subquery contains EXCEPT or EXCEPT ALL set ops we cannot push
* 2. If the subquery contains any window functions, we can't push quals
* into it, because that would change the results.
*
* 3. If the subquery contains EXCEPT or EXCEPT ALL set ops we cannot push
* quals into it, because that would change the results.
*
* 3. For subqueries using UNION/UNION ALL/INTERSECT/INTERSECT ALL, we can
* 4. For subqueries using UNION/UNION ALL/INTERSECT/INTERSECT ALL, we can
* push quals into each component query, but the quals can only reference
* subquery columns that suffer no type coercions in the set operation.
* Otherwise there are possible semantic gotchas. So, we check the
@ -950,6 +953,10 @@ subquery_is_pushdown_safe(Query *subquery, Query *topquery,
if (subquery->limitOffset != NULL || subquery->limitCount != NULL)
return false;
/* Check point 2 */
if (subquery->hasWindowFuncs)
return false;
/* Are we at top level, or looking at a setop component? */
if (subquery == topquery)
{
@ -1092,6 +1099,12 @@ qual_is_pushdown_safe(Query *subquery, Index rti, Node *qual,
if (contain_subplans(qual))
return false;
/*
* It would be unsafe to push down window function calls, but at least
* for the moment we could never see any in a qual anyhow.
*/
Assert(!contain_window_function(qual));
/*
* Examine all Vars used in clause; since it's a restriction clause, all
* such Vars must refer to subselect output columns.