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| author | Tom Lane <tgl@sss.pgh.pa.us> | 1999-11-15 02:00:15 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 1999-11-15 02:00:15 +0000 |
| commit | f68e11f373de8b7b1d19203b8edac1a13a8d406d (patch) | |
| tree | c4e61de2b9bd9b8dd7c70545dc861de3547294d4 /src/backend/optimizer/plan/planmain.c | |
| parent | 1ecb129d206f30f5813b01e1f1efe75c06febe49 (diff) | |
| download | postgresql-f68e11f373de8b7b1d19203b8edac1a13a8d406d.tar.gz postgresql-f68e11f373de8b7b1d19203b8edac1a13a8d406d.zip | |
Implement subselects in target lists. Also, relax requirement that
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.
Diffstat (limited to 'src/backend/optimizer/plan/planmain.c')
| -rw-r--r-- | src/backend/optimizer/plan/planmain.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/src/backend/optimizer/plan/planmain.c b/src/backend/optimizer/plan/planmain.c index 3b289fb3d0e..7da2ee4c211 100644 --- a/src/backend/optimizer/plan/planmain.c +++ b/src/backend/optimizer/plan/planmain.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planmain.c,v 1.46 1999/10/07 04:23:06 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planmain.c,v 1.47 1999/11/15 02:00:07 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -87,9 +87,25 @@ query_planner(Query *root, tlist = (List *) SS_replace_correlation_vars((Node *) tlist); qual = (List *) SS_replace_correlation_vars((Node *) qual); } + /* Expand SubLinks to SubPlans */ if (root->hasSubLinks) + { + tlist = (List *) SS_process_sublinks((Node *) tlist); qual = (List *) SS_process_sublinks((Node *) qual); + if (root->groupClause != NIL) + { + /* + * Check for ungrouped variables passed to subplans. + * Note we do NOT do this for subplans in WHERE; it's legal + * there because WHERE is evaluated pre-GROUP. + */ + if (check_subplans_for_ungrouped_vars((Node *) tlist, + root->groupClause, + tlist)) + elog(ERROR, "Sub-SELECT must use only GROUPed attributes from outer SELECT"); + } + } /* * If the query contains no relation references at all, it must be |