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Restructure planning code so that preprocessing of targetlist and quals

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to simplify constant expressions and expand SubLink nodes into SubPlans
is done in a separate routine subquery_planner() that calls union_planner().
We formerly did most of this work in query_planner(), but that's the
wrong place because it may never see the real targetlist.  Splitting
union_planner into two routines also allows us to avoid redundant work
when union_planner is invoked recursively for UNION and inheritance
cases.  Upshot is that it is now possible to do something like
select float8(count(*)) / (select count(*) from int4_tbl)  from int4_tbl
group by f1;
which has never worked before.
This commit is contained in:
Tom Lane
2000-03-21 05:12:12 +00:00
parent aafe86d995
commit 3ee8f7e207
8 changed files with 191 additions and 166 deletions
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37
src/backend/optimizer/util/clauses.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.62 2000/03/19 18:20:38 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.63 2000/03/21 05:12:12 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@@ -41,15 +41,10 @@
((Node *) makeConst(BOOLOID, 1, (Datum) (val), \
(isnull), true, false, false))
typedef struct {
Query *query;
List *targetList;
} check_subplans_for_ungrouped_vars_context;
static bool contain_agg_clause_walker(Node *node, void *context);
static bool pull_agg_clause_walker(Node *node, List **listptr);
static bool check_subplans_for_ungrouped_vars_walker(Node *node,
check_subplans_for_ungrouped_vars_context *context);
Query *context);
static int is_single_func(Node *node);
static Node *eval_const_expressions_mutator (Node *node, void *context);
static Expr *simplify_op_or_func(Expr *expr, List *args);
@@ -467,30 +462,24 @@ pull_agg_clause_walker(Node *node, List **listptr)
* In most contexts, ungrouped variables will be detected by the parser (see
* parse_agg.c, check_ungrouped_columns()). But that routine currently does
* not check subplans, because the necessary info is not computed until the
* planner runs. So we do it here, after we have processed the subplan.
* This ought to be cleaned up someday.
* planner runs. So we do it here, after we have processed sublinks into
* subplans. This ought to be cleaned up someday.
*
* 'clause' is the expression tree to be searched for subplans.
* 'query' provides the GROUP BY list and range table.
* 'targetList' is the target list that the group clauses refer to.
* (Is it really necessary to pass the tlist separately? Couldn't we
* just use the tlist found in the query node?)
* 'query' provides the GROUP BY list, the target list that the group clauses
* refer to, and the range table.
*/
void
check_subplans_for_ungrouped_vars(Node *clause,
Query *query,
List *targetList)
Query *query)
{
check_subplans_for_ungrouped_vars_context context;
context.query = query;
context.targetList = targetList;
check_subplans_for_ungrouped_vars_walker(clause, &context);
/* No special setup needed; context for walker is just the Query pointer */
check_subplans_for_ungrouped_vars_walker(clause, query);
}
static bool
check_subplans_for_ungrouped_vars_walker(Node *node,
check_subplans_for_ungrouped_vars_context *context)
Query *context)
{
if (node == NULL)
return false;
@@ -529,7 +518,7 @@ check_subplans_for_ungrouped_vars_walker(Node *node,
* Else, see if it is a grouping column.
*/
contained_in_group_clause = false;
foreach(gl, context->query->groupClause)
foreach(gl, context->groupClause)
{
GroupClause *gcl = lfirst(gl);
Node *groupexpr;
@@ -550,8 +539,8 @@ check_subplans_for_ungrouped_vars_walker(Node *node,
char *attname;
Assert(var->varno > 0 &&
var->varno <= length(context->query->rtable));
rte = rt_fetch(var->varno, context->query->rtable);
var->varno <= length(context->rtable));
rte = rt_fetch(var->varno, context->rtable);
attname = get_attname(rte->relid, var->varattno);
if (! attname)
elog(ERROR, "cache lookup of attribute %d in relation %u failed",