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documentation for HAVING, clean up UNION comment.

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Bruce Momjian
1998-03-30 19:05:10 +00:00
parent ef0eecfa1f
commit 01ecb2e3a0
3 changed files with 27 additions and 7 deletions
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26
src/backend/optimizer/prep/prepunion.c
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@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.20 1998/02/26 04:33:05 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.21 1998/03/30 19:04:41 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -71,7 +71,8 @@ plan_union_queries(Query *parse)
union_found = false,
last_unionall_flag = false;
/*
/*------------------------------------------------------------------
*
* Do we need to split up our unions because we have UNION and UNION
* ALL?
*
@@ -87,10 +88,25 @@ plan_union_queries(Query *parse)
*
* So the above query becomes:
*
* Append Node { Sort and Unique { Append Node { SELECT 1
* This is really a sub-UNION, unionClause We run a
* DISTINCT on these. { SELECT 2 SELECT 3 } } } SELECT 4 SELECT 5 }
* Append Node
* {
* Sort and Unique
* {
* Append Node
* {
* SELECT 1 This is really a sub-UNION.
* unionClause We run a DISTINCT on these.
* {
* SELECT 2
* SELECT 3
* }
* }
* }
* SELECT 4
* SELECT 5
* }
*
*---------------------------------------------------------------------
*/
foreach(ulist, parse->unionClause)