From 1df7a455dd37021b5588166b80f37fe36f674e67 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 20 Oct 2003 20:01:59 +0000
Subject: [PATCH] It is possible for ResolveNew to be used to insert a sublink
into a subquery that didn't previously have one. We have traditionally made
the caller of ResolveNew responsible for updating the hasSubLinks flag of the
outermost query, but this fails to account for hasSubLinks in subqueries.
Fix ResolveNew to handle this. We might later want to change the calling
convention of ResolveNew so that it can fix the outer query too, simplifying
callers. But I went with the localized fix for now. Per bug report from J
Smith, 20-Oct-03.
---
src/backend/rewrite/rewriteManip.c | 36 +++++++++++++++++++++++-------
1 file changed, 28 insertions(+), 8 deletions(-)
diff --git a/src/backend/rewrite/rewriteManip.c b/src/backend/rewrite/rewriteManip.c
index ea48d2f07a3..17c13d68585 100644
--- a/src/backend/rewrite/rewriteManip.c
+++ b/src/backend/rewrite/rewriteManip.c
@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteManip.c,v 1.79 2003/09/25 06:58:01 petere Exp $
+ * $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteManip.c,v 1.80 2003/10/20 20:01:59 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -99,7 +99,7 @@ bool
checkExprHasSubLink(Node *node)
{
/*
- * If a Query is passed, examine it --- but we will not recurse into
+ * If a Query is passed, examine it --- but we need not recurse into
* sub-Queries.
*/
return query_or_expression_tree_walker(node,
@@ -755,10 +755,12 @@ AddQual(Query *parsetree, Node *qual)
/*
* Make sure query is marked correctly if added qual has sublinks or
* aggregates (not sure it can ever have aggs, but sublinks
- * definitely).
+ * definitely). Need not search qual when query is already marked.
*/
- parsetree->hasAggs |= checkExprHasAggs(copy);
- parsetree->hasSubLinks |= checkExprHasSubLink(copy);
+ if (!parsetree->hasAggs)
+ parsetree->hasAggs = checkExprHasAggs(copy);
+ if (!parsetree->hasSubLinks)
+ parsetree->hasSubLinks = checkExprHasSubLink(copy);
}
/*
@@ -809,10 +811,12 @@ AddHavingQual(Query *parsetree, Node *havingQual)
/*
* Make sure query is marked correctly if added qual has sublinks or
* aggregates (not sure it can ever have aggs, but sublinks
- * definitely).
+ * definitely). Need not search qual when query is already marked.
*/
- parsetree->hasAggs |= checkExprHasAggs(copy);
- parsetree->hasSubLinks |= checkExprHasSubLink(copy);
+ if (!parsetree->hasAggs)
+ parsetree->hasAggs = checkExprHasAggs(copy);
+ if (!parsetree->hasSubLinks)
+ parsetree->hasSubLinks = checkExprHasSubLink(copy);
}
@@ -845,6 +849,12 @@ AddInvertedQual(Query *parsetree, Node *qual)
* entry with matching resno from targetlist, if there is one.
* If not, we either change the unmatched Var's varno to update_varno
* (when event == CMD_UPDATE) or replace it with a constant NULL.
+ *
+ * Note: the business with inserted_sublink is needed to update hasSubLinks
+ * in subqueries when the replacement adds a subquery inside a subquery.
+ * Messy, isn't it? We do not need to do similar pushups for hasAggs,
+ * because it isn't possible for this transformation to insert a level-zero
+ * aggregate reference into a subquery --- it could only insert outer aggs.
*/
typedef struct
@@ -854,6 +864,7 @@ typedef struct
List *targetlist;
int event;
int update_varno;
+ bool inserted_sublink;
} ResolveNew_context;
static Node *
@@ -904,6 +915,9 @@ ResolveNew_mutator(Node *node, ResolveNew_context *context)
/* Adjust varlevelsup if tlist item is from higher query */
if (this_varlevelsup > 0)
IncrementVarSublevelsUp(n, this_varlevelsup, 0);
+ /* Report it if we are adding a sublink to query */
+ if (!context->inserted_sublink)
+ context->inserted_sublink = checkExprHasSubLink(n);
return n;
}
}
@@ -914,12 +928,17 @@ ResolveNew_mutator(Node *node, ResolveNew_context *context)
{
/* Recurse into RTE subquery or not-yet-planned sublink subquery */
Query *newnode;
+ bool save_inserted_sublink;
context->sublevels_up++;
+ save_inserted_sublink = context->inserted_sublink;
+ context->inserted_sublink = false;
newnode = query_tree_mutator((Query *) node,
ResolveNew_mutator,
(void *) context,
0);
+ newnode->hasSubLinks |= context->inserted_sublink;
+ context->inserted_sublink = save_inserted_sublink;
context->sublevels_up--;
return (Node *) newnode;
}
@@ -938,6 +957,7 @@ ResolveNew(Node *node, int target_varno, int sublevels_up,
context.targetlist = targetlist;
context.event = event;
context.update_varno = update_varno;
+ context.inserted_sublink = false;
/*
* Must be prepared to start with a Query or a bare expression tree;
--
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