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Commitd24ef0d

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Make EXPLAIN results for Append, Group, Agg, Unique nodes more plausible.
Group and Unique use an arbitrary assumption that there will be about10% as many groups as input tuples --- perhaps someday we can refine this.
1 parent40055db commitd24ef0d

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2 files changed

+59
-35
lines changed

2 files changed

+59
-35
lines changed

‎src/backend/optimizer/plan/createplan.c‎

Lines changed: 37 additions & 22 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
*
1111
*
1212
* IDENTIFICATION
13-
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.82 2000/01/27 18:11:30 tgl Exp $
13+
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.83 2000/02/03 06:12:18 tgl Exp $
1414
*
1515
*-------------------------------------------------------------------------
1616
*/
@@ -743,9 +743,9 @@ create_hashjoin_node(HashPath *best_path,
743743
** Var nodes representing index keys must have varattno equal to the
744744
* index's attribute number, not the attribute number in the original rel.
745745
** indxpath.c may have selected an index that is binary-compatible with
746-
* the actual expression operator, but not the same; we must replace the
747-
* expression's operator with the binary-compatible equivalent operator
748-
* that the index will recognize.
746+
* the actual expression operator, but notexactlythe same datatype.
747+
*We must replace theexpression's operator with the binary-compatible
748+
*equivalent operatorthat the index will recognize.
749749
** If the index key is on the right, commute the clause to put it on the
750750
* left. (Someday the executor might not need this, but for now it does.)
751751
*
@@ -1054,6 +1054,7 @@ copy_path_costsize(Plan *dest, Path *src)
10541054
* Copy cost and size info from a lower plan node to an inserted node.
10551055
* This is not critical, since the decisions have already been made,
10561056
* but it helps produce more reasonable-looking EXPLAIN output.
1057+
* (Some callers alter the info after copying it.)
10571058
*/
10581059
staticvoid
10591060
copy_plan_costsize(Plan*dest,Plan*src)
@@ -1178,12 +1179,7 @@ make_nestloop(List *qptlist,
11781179
NestLoop*node=makeNode(NestLoop);
11791180
Plan*plan=&node->join;
11801181

1181-
/*
1182-
* this cost estimate is entirely bogus... hopefully it will be
1183-
* overwritten by caller.
1184-
*/
1185-
plan->cost= (lefttree ?lefttree->cost :0)+
1186-
(righttree ?righttree->cost :0);
1182+
/* cost should be inserted by caller */
11871183
plan->state= (EState*)NULL;
11881184
plan->targetlist=qptlist;
11891185
plan->qual=qpqual;
@@ -1204,12 +1200,7 @@ make_hashjoin(List *tlist,
12041200
HashJoin*node=makeNode(HashJoin);
12051201
Plan*plan=&node->join;
12061202

1207-
/*
1208-
* this cost estimate is entirely bogus... hopefully it will be
1209-
* overwritten by caller.
1210-
*/
1211-
plan->cost= (lefttree ?lefttree->cost :0)+
1212-
(righttree ?righttree->cost :0);
1203+
/* cost should be inserted by caller */
12131204
plan->state= (EState*)NULL;
12141205
plan->targetlist=tlist;
12151206
plan->qual=qpqual;
@@ -1248,12 +1239,7 @@ make_mergejoin(List *tlist,
12481239
MergeJoin*node=makeNode(MergeJoin);
12491240
Plan*plan=&node->join;
12501241

1251-
/*
1252-
* this cost estimate is entirely bogus... hopefully it will be
1253-
* overwritten by caller.
1254-
*/
1255-
plan->cost= (lefttree ?lefttree->cost :0)+
1256-
(righttree ?righttree->cost :0);
1242+
/* cost should be inserted by caller */
12571243
plan->state= (EState*)NULL;
12581244
plan->targetlist=tlist;
12591245
plan->qual=qpqual;
@@ -1293,6 +1279,7 @@ make_material(List *tlist,
12931279
Plan*plan=&node->plan;
12941280

12951281
copy_plan_costsize(plan,lefttree);
1282+
/* XXX shouldn't we charge some additional cost for materialization? */
12961283
plan->state= (EState*)NULL;
12971284
plan->targetlist=tlist;
12981285
plan->qual=NIL;
@@ -1310,6 +1297,20 @@ make_agg(List *tlist, Plan *lefttree)
13101297
Agg*node=makeNode(Agg);
13111298

13121299
copy_plan_costsize(&node->plan,lefttree);
1300+
/*
1301+
* The tuple width from the input node is OK, as is the cost (we are
1302+
* ignoring the cost of computing the aggregate; is there any value
1303+
* in accounting for it?). But the tuple count is bogus. We will
1304+
* produce a single tuple if the input is not a Group, and a tuple
1305+
* per group otherwise. For now, estimate the number of groups as
1306+
* 10% of the number of tuples --- bogus, but how to do better?
1307+
* (Note we assume the input Group node is in "tuplePerGroup" mode,
1308+
* so it didn't reduce its row count already.)
1309+
*/
1310+
if (IsA(lefttree,Group))
1311+
node->plan.plan_rows *=0.1;
1312+
else
1313+
node->plan.plan_rows=1;
13131314
node->plan.state= (EState*)NULL;
13141315
node->plan.qual=NULL;
13151316
node->plan.targetlist=tlist;
@@ -1329,6 +1330,15 @@ make_group(List *tlist,
13291330
Group*node=makeNode(Group);
13301331

13311332
copy_plan_costsize(&node->plan,lefttree);
1333+
/*
1334+
* If tuplePerGroup (which is named exactly backwards) is true,
1335+
* we will return all the input tuples, so the input node's row count
1336+
* is OK. Otherwise, we'll return only one tuple from each group.
1337+
* For now, estimate the number of groups as 10% of the number of
1338+
* tuples --- bogus, but how to do better?
1339+
*/
1340+
if (!tuplePerGroup)
1341+
node->plan.plan_rows *=0.1;
13321342
node->plan.state= (EState*)NULL;
13331343
node->plan.qual=NULL;
13341344
node->plan.targetlist=tlist;
@@ -1357,6 +1367,11 @@ make_unique(List *tlist, Plan *lefttree, List *distinctList)
13571367
List*slitem;
13581368

13591369
copy_plan_costsize(plan,lefttree);
1370+
/*
1371+
* As for Group, we make the unsupported assumption that there will be
1372+
* 10% as many tuples out as in.
1373+
*/
1374+
plan->plan_rows *=0.1;
13601375
plan->state= (EState*)NULL;
13611376
plan->targetlist=tlist;
13621377
plan->qual=NIL;

‎src/backend/optimizer/prep/prepunion.c‎

Lines changed: 22 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.42 2000/01/27 18:11:32 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.43 2000/02/03 06:12:19 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -218,11 +218,11 @@ plan_union_queries(Query *parse)
218218
parse->havingQual=NULL;
219219
parse->hasAggs= false;
220220

221-
return(make_append(union_plans,
222-
union_rts,
223-
0,
224-
NULL,
225-
parse->targetList));
221+
returnmake_append(union_plans,
222+
union_rts,
223+
0,
224+
NULL,
225+
parse->targetList);
226226
}
227227

228228

@@ -272,11 +272,11 @@ plan_inherit_queries(Query *parse, List *tlist, Index rt_index)
272272
union_plans=plan_inherit_query(union_relids,rt_index,rt_entry,
273273
parse,tlist,&inheritrtable);
274274

275-
return(make_append(union_plans,
276-
NULL,
277-
rt_index,
278-
inheritrtable,
279-
((Plan*)lfirst(union_plans))->targetlist));
275+
returnmake_append(union_plans,
276+
NULL,
277+
rt_index,
278+
inheritrtable,
279+
((Plan*)lfirst(union_plans))->targetlist);
280280
}
281281

282282
/*
@@ -551,9 +551,18 @@ make_append(List *appendplans,
551551
node->unionrtables=unionrtables;
552552
node->inheritrelid=rt_index;
553553
node->inheritrtable=inheritrtable;
554-
node->plan.cost=0.0;
554+
node->plan.cost=0;
555+
node->plan.plan_rows=0;
556+
node->plan.plan_width=0;
555557
foreach(subnode,appendplans)
556-
node->plan.cost+= ((Plan*)lfirst(subnode))->cost;
558+
{
559+
Plan*subplan= (Plan*)lfirst(subnode);
560+
561+
node->plan.cost+=subplan->cost;
562+
node->plan.plan_rows+=subplan->plan_rows;
563+
if (node->plan.plan_width<subplan->plan_width)
564+
node->plan.plan_width=subplan->plan_width;
565+
}
557566
node->plan.state= (EState*)NULL;
558567
node->plan.targetlist=tlist;
559568
node->plan.qual=NIL;

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