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Dept of better ideas: refrain from creating the planner's placeholder_list

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until vars are distributed to rels during query_planner() startup.  We don't
really need it before that, and not building it early has some advantages.
First, we don't need to put it through the various preprocessing steps, which
saves some cycles and eliminates the need for a number of routines to support
PlaceHolderInfo nodes at all.  Second, this means one less unused plan for any
sub-SELECT appearing in a placeholder's expression, since we don't build
placeholder_list until after sublink expansion is complete.
This commit is contained in:
Tom Lane
2008-10-22 20:17:52 +00:00
parent b9856b67a7
commit 31468d05d8
8 changed files with 95 additions and 168 deletions
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23
src/backend/optimizer/util/var.c
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@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/util/var.c,v 1.81 2008/10/21 20:42:53 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/util/var.c,v 1.82 2008/10/22 20:17:52 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -800,24 +800,6 @@ flatten_join_alias_vars_mutator(Node *node,
}
return (Node *) phv;
}
if (IsA(node, PlaceHolderInfo))
{
/* Copy the PlaceHolderInfo node with correct mutation of subnodes */
PlaceHolderInfo *phinfo;
phinfo = (PlaceHolderInfo *) expression_tree_mutator(node,
flatten_join_alias_vars_mutator,
(void *) context);
/* now fix PlaceHolderInfo's relid sets */
if (context->sublevels_up == 0)
{
phinfo->ph_eval_at = alias_relid_set(context->root,
phinfo->ph_eval_at);
phinfo->ph_needed = alias_relid_set(context->root,
phinfo->ph_needed);
}
return (Node *) phinfo;
}
if (IsA(node, Query))
{
@ -834,6 +816,9 @@ flatten_join_alias_vars_mutator(Node *node,
}
/* Already-planned tree not supported */
Assert(!IsA(node, SubPlan));
/* Shouldn't need to handle these planner auxiliary nodes here */
Assert(!IsA(node, SpecialJoinInfo));
Assert(!IsA(node, PlaceHolderInfo));
return expression_tree_mutator(node, flatten_join_alias_vars_mutator,
(void *) context);