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Phase 2 of hashed-aggregation project. nodeAgg.c now knows how to do

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hashed aggregation, but there's not yet planner support for it.
This commit is contained in:
Tom Lane
2002-11-06 22:31:24 +00:00
parent fc9814d17e
commit 2103b7baa2
12 changed files with 696 additions and 266 deletions
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63
src/backend/optimizer/plan/planner.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.126 2002/11/06 00:00:44 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.127 2002/11/06 22:31:24 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -931,6 +931,7 @@ grouping_planner(Query *parse, double tuple_fraction)
AttrNumber *groupColIdx = NULL;
Path *cheapest_path;
Path *sorted_path;
bool use_hashed_grouping = false;
/* Preprocess targetlist in case we are inside an INSERT/UPDATE. */
tlist = preprocess_targetlist(tlist,
@ -1209,6 +1210,29 @@ grouping_planner(Query *parse, double tuple_fraction)
group_pathkeys = canonicalize_pathkeys(parse, group_pathkeys);
sort_pathkeys = canonicalize_pathkeys(parse, sort_pathkeys);
/*
* Consider whether we might want to use hashed grouping.
*/
if (parse->groupClause)
{
/*
* Executor doesn't support hashed aggregation with DISTINCT
* aggregates. (Doing so would imply storing *all* the input
* values in the hash table, which seems like a certain loser.)
*/
if (parse->hasAggs &&
(contain_distinct_agg_clause((Node *) tlist) ||
contain_distinct_agg_clause(parse->havingQual)))
use_hashed_grouping = false;
else
{
#if 0 /* much more to do here */
/* TEMPORARY HOTWIRE FOR TESTING */
use_hashed_grouping = true;
#endif
}
}
/*
* Select the best path and create a plan to execute it.
*
@ -1279,22 +1303,30 @@ grouping_planner(Query *parse, double tuple_fraction)
}
/*
* If any aggregate is present, insert the Agg node, plus an explicit
* sort if necessary.
* Insert AGG or GROUP node if needed, plus an explicit sort step
* if necessary.
*
* HAVING clause, if any, becomes qual of the Agg node
*/
if (parse->hasAggs)
if (use_hashed_grouping)
{
/* Hashed aggregate plan --- no sort needed */
result_plan = (Plan *) make_agg(tlist,
(List *) parse->havingQual,
AGG_HASHED,
length(parse->groupClause),
groupColIdx,
result_plan);
/* Hashed aggregation produces randomly-ordered results */
current_pathkeys = NIL;
}
else if (parse->hasAggs)
{
/* Plain aggregate plan --- sort if needed */
AggStrategy aggstrategy;
if (parse->groupClause)
{
aggstrategy = AGG_SORTED;
/*
* Add an explicit sort if we couldn't make the path come out
* the way the AGG node needs it.
*/
if (!pathkeys_contained_in(group_pathkeys, current_pathkeys))
{
result_plan = make_groupsortplan(parse,
@ -1303,9 +1335,18 @@ grouping_planner(Query *parse, double tuple_fraction)
result_plan);
current_pathkeys = group_pathkeys;
}
aggstrategy = AGG_SORTED;
/*
* The AGG node will not change the sort ordering of its
* groups, so current_pathkeys describes the result too.
*/
}
else
{
aggstrategy = AGG_PLAIN;
/* Result will be only one row anyway; no sort order */
current_pathkeys = NIL;
}
result_plan = (Plan *) make_agg(tlist,
(List *) parse->havingQual,
@ -1313,10 +1354,6 @@ grouping_planner(Query *parse, double tuple_fraction)
length(parse->groupClause),
groupColIdx,
result_plan);
/*
* Note: plain or grouped Agg does not affect any existing
* sort order of the tuples
*/
}
else
{