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Turn the rangetable used by the executor into a flat list, and avoid storing

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useless substructure for its RangeTblEntry nodes.  (I chose to keep using the
same struct node type and just zero out the link fields for unneeded info,
rather than making a separate ExecRangeTblEntry type --- it seemed too
fragile to have two different rangetable representations.)

Along the way, put subplans into a list in the toplevel PlannedStmt node,
and have SubPlan nodes refer to them by list index instead of direct pointers.
Vadim wanted to do that years ago, but I never understood what he was on about
until now.  It makes things a *whole* lot more robust, because we can stop
worrying about duplicate processing of subplans during expression tree
traversals.  That's been a constant source of bugs, and it's finally gone.

There are some consequent simplifications yet to be made, like not using
a separate EState for subplans in the executor, but I'll tackle that later.
This commit is contained in:
Tom Lane
2007-02-22 22:00:26 +00:00
parent 849000c782
commit eab6b8b27e
32 changed files with 841 additions and 1004 deletions
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35
src/backend/optimizer/prep/prepunion.c
View File

@ -22,7 +22,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.138 2007/02/19 07:03:30 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.139 2007/02/22 22:00:24 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -169,6 +169,7 @@ recurse_set_operations(Node *setOp, PlannerInfo *root,
RangeTblRef *rtr = (RangeTblRef *) setOp;
RangeTblEntry *rte = rt_fetch(rtr->rtindex, root->parse->rtable);
Query *subquery = rte->subquery;
PlannerInfo *subroot;
Plan *subplan,
*plan;
@ -180,7 +181,7 @@ recurse_set_operations(Node *setOp, PlannerInfo *root,
subplan = subquery_planner(root->glob, subquery,
root->query_level + 1,
tuple_fraction,
NULL);
&subroot);
/*
* Add a SubqueryScan with the caller-requested targetlist
@ -193,7 +194,8 @@ recurse_set_operations(Node *setOp, PlannerInfo *root,
refnames_tlist),
NIL,
rtr->rtindex,
subplan);
subplan,
subroot->parse->rtable);
/*
* We don't bother to determine the subquery's output ordering since
@ -223,7 +225,7 @@ recurse_set_operations(Node *setOp, PlannerInfo *root,
* output columns.
*
* XXX you don't really want to know about this: setrefs.c will apply
* replace_vars_with_subplan_refs() to the Result node's tlist. This
* fix_upper_expr() to the Result node's tlist. This
* would fail if the Vars generated by generate_setop_tlist() were not
* exactly equal() to the corresponding tlist entries of the subplan.
* However, since the subplan was generated by generate_union_plan()
@ -235,7 +237,8 @@ recurse_set_operations(Node *setOp, PlannerInfo *root,
!tlist_same_datatypes(plan->targetlist, colTypes, junkOK))
{
plan = (Plan *)
make_result(generate_setop_tlist(colTypes, flag,
make_result(root,
generate_setop_tlist(colTypes, flag,
0,
false,
plan->targetlist,
@ -1216,28 +1219,6 @@ adjust_appendrel_attrs_mutator(Node *node, AppendRelInfo *context)
Assert(!IsA(node, SubLink));
Assert(!IsA(node, Query));
/*
* BUT: although we don't need to recurse into subplans, we do need to
* make sure that they are copied, not just referenced as
* expression_tree_mutator will do by default. Otherwise we'll have the
* same subplan node referenced from each arm of the finished APPEND plan,
* which will cause trouble in the executor. This is a kluge that should
* go away when we redesign querytrees.
*/
if (is_subplan(node))
{
SubPlan *subplan;
/* Copy the node and process subplan args */
node = expression_tree_mutator(node, adjust_appendrel_attrs_mutator,
(void *) context);
/* Make sure we have separate copies of subplan and its rtable */
subplan = (SubPlan *) node;
subplan->plan = copyObject(subplan->plan);
subplan->rtable = copyObject(subplan->rtable);
return node;
}
return expression_tree_mutator(node, adjust_appendrel_attrs_mutator,
(void *) context);
}