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Implement subselects in target lists. Also, relax requirement that

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subselects can only appear on the righthand side of a binary operator.
That's still true for quantified predicates like x = ANY (SELECT ...),
but a subselect that delivers a single result can now appear anywhere
in an expression.  This is implemented by changing EXPR_SUBLINK sublinks
to represent just the (SELECT ...) expression, without any 'left hand
side' or combining operator --- so they're now more like EXISTS_SUBLINK.
To handle the case of '(x, y, z) = (SELECT ...)', I added a new sublink
type MULTIEXPR_SUBLINK, which acts just like EXPR_SUBLINK used to.
But the grammar will only generate one for a multiple-left-hand-side
row expression.
This commit is contained in:
Tom Lane
1999-11-15 02:00:15 +00:00
parent 1ecb129d20
commit f68e11f373
12 changed files with 364 additions and 566 deletions
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12
src/backend/optimizer/plan/planner.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.70 1999/10/07 04:23:06 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.71 1999/11/15 02:00:08 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -343,17 +343,11 @@ union_planner(Query *parse)
{
/* Expand SubLinks to SubPlans */
parse->havingQual = SS_process_sublinks(parse->havingQual);
/*
* Check for ungrouped variables passed to subplans. (Probably
* this should be done for the targetlist as well??? But we
* should NOT do it for the WHERE qual, since WHERE is
* evaluated pre-GROUP.)
*/
/* Check for ungrouped variables passed to subplans */
if (check_subplans_for_ungrouped_vars(parse->havingQual,
parse->groupClause,
parse->targetList))
elog(ERROR, "Sub-SELECT in HAVING clause must use only GROUPed attributes from outer SELECT");
elog(ERROR, "Sub-SELECT must use only GROUPed attributes from outer SELECT");
}
}