Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit605d849

Browse files
committed
Clean up cost_sort some more: most callers were double-counting
the cost of reading the source data.
1 parent87d95ca commit605d849

File tree

4 files changed

+20
-26
lines changed

4 files changed

+20
-26
lines changed

‎src/backend/optimizer/path/costsize.c‎

Lines changed: 13 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.35 1999/04/30 04:01:44 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.36 1999/05/01 19:47:41 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -167,28 +167,23 @@ cost_index(Oid indexid,
167167
/*
168168
* cost_sort
169169
* Determines and returns the cost of sorting a relation by considering
170-
*1.the cost of doing an external sort:XXX this is probably too low
170+
* the cost of doing an external sort:XXX this is probably too low
171171
*disk = (p lg p)
172172
*cpu = *CPU-PAGE-WEIGHT* * (t lg t)
173-
* 2. the cost of reading the sort result into memory (another seqscan)
174-
* unless 'noread' is set
175173
*
176174
* 'pathkeys' is a list of sort keys
177175
* 'tuples' is the number of tuples in the relation
178176
* 'width' is the average tuple width in bytes
179-
* 'noread' is a flag indicating that the cost of reading the sort
180-
*source data should not be included (i.e., the caller
181-
*will account for it separately).
182177
*
183178
* NOTE: some callers currently pass NULL for pathkeys because they
184-
* can't conveniently supply sort keys. Since this routine doesn't
179+
* can't conveniently supplythesort keys. Since this routine doesn't
185180
* currently do anything with pathkeys anyway, that doesn't matter...
181+
* but if it ever does, it should react gracefully to lack of key data.
186182
*
187183
* Returns a flonum.
188-
*
189184
*/
190185
Cost
191-
cost_sort(List*pathkeys,inttuples,intwidth,boolnoread)
186+
cost_sort(List*pathkeys,inttuples,intwidth)
192187
{
193188
Costtemp=0;
194189
intnpages=page_size(tuples,width);
@@ -200,6 +195,8 @@ cost_sort(List *pathkeys, int tuples, int width, bool noread)
200195
/* We want to be sure the cost of a sort is never estimated as zero,
201196
* even if passed-in tuple count is zero. Besides, mustn't do log(0)...
202197
*/
198+
if (tuples <=0)
199+
tuples=1;
203200
if (npages <=0)
204201
npages=1;
205202

@@ -210,13 +207,10 @@ cost_sort(List *pathkeys, int tuples, int width, bool noread)
210207
temp+=npages*log_npages;
211208

212209
/*
213-
* could be base_log(pages, NBuffers), but we are only doing 2-way
210+
* could be base_log(tuples, NBuffers), but we are only doing 2-way
214211
* merges
215212
*/
216-
temp+=_cpu_page_wight_*tuples*log_npages;
217-
218-
if (!noread)
219-
temp+=cost_seqscan(_NONAME_RELATION_ID_,npages,tuples);
213+
temp+=_cpu_page_wight_*tuples*base_log((double)tuples,2.0);
220214

221215
Assert(temp>0);
222216

@@ -282,7 +276,8 @@ cost_nestloop(Cost outercost,
282276
* 'outercost' and 'innercost' are the (disk+cpu) costs of scanning the
283277
*outer and inner relations
284278
* 'outersortkeys' and 'innersortkeys' are lists of the keys to be used
285-
*to sort the outer and inner relations
279+
*to sort the outer and inner relations (or NIL if no explicit
280+
*sort is needed because the source path is already ordered)
286281
* 'outertuples' and 'innertuples' are the number of tuples in the outer
287282
*and inner relations
288283
* 'outerwidth' and 'innerwidth' are the (typical) widths (in bytes)
@@ -309,9 +304,9 @@ cost_mergejoin(Cost outercost,
309304
temp+=outercost;
310305
temp+=innercost;
311306
if (outersortkeys)/* do we need to sort? */
312-
temp+=cost_sort(outersortkeys,outersize,outerwidth, true);
307+
temp+=cost_sort(outersortkeys,outersize,outerwidth);
313308
if (innersortkeys)/* do we need to sort? */
314-
temp+=cost_sort(innersortkeys,innersize,innerwidth, true);
309+
temp+=cost_sort(innersortkeys,innersize,innerwidth);
315310
temp+=_cpu_page_wight_* (outersize+innersize);
316311

317312
Assert(temp >=0);

‎src/backend/optimizer/path/joinpath.c‎

Lines changed: 3 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.33 1999/04/03 00:18:28 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.34 1999/05/01 19:47:42 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -348,7 +348,7 @@ match_unsorted_outer(RelOptInfo *joinrel,
348348
(mergeinnerpath->path_cost<
349349
(cheapest_inner->path_cost+
350350
cost_sort(matchedJoinKeys,innerrel->size,
351-
innerrel->width, false))));
351+
innerrel->width))));
352352
if (!path_is_cheaper_than_sort)
353353
{
354354
varkeys=make_pathkeys_from_joinkeys(matchedJoinKeys,
@@ -464,8 +464,7 @@ match_unsorted_inner(RelOptInfo *joinrel,
464464
if (clauses&&matchedJoinKeys)
465465
{
466466
temp1=outerrel->cheapestpath->path_cost+
467-
cost_sort(matchedJoinKeys,outerrel->size,outerrel->width,
468-
false);
467+
cost_sort(matchedJoinKeys,outerrel->size,outerrel->width);
469468

470469
temp2= (bool) (FLOAT_IS_ZERO(innerpath->outerjoincost)
471470
|| (innerpath->outerjoincost>temp1));

‎src/backend/optimizer/plan/createplan.c‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.51 1999/04/30 04:04:27 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.52 1999/05/01 19:47:40 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -1106,7 +1106,7 @@ make_sort(List *tlist, Oid nonameid, Plan *lefttree, int keycount)
11061106
Plan*plan=&node->plan;
11071107

11081108
copy_costsize(plan,lefttree);
1109-
plan->cost+=cost_sort(NULL,plan->plan_size,plan->plan_width, true);
1109+
plan->cost+=cost_sort(NULL,plan->plan_size,plan->plan_width);
11101110
plan->state= (EState*)NULL;
11111111
plan->targetlist=tlist;
11121112
plan->qual=NIL;

‎src/include/optimizer/cost.h‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
*
77
* Copyright (c) 1994, Regents of the University of California
88
*
9-
* $Id: cost.h,v 1.17 1999/02/13 23:21:43 momjian Exp $
9+
* $Id: cost.h,v 1.18 1999/05/01 19:47:39 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -34,7 +34,7 @@ extern Cost cost_seqscan(int relid, int relpages, int reltuples);
3434
externCostcost_index(Oidindexid,intexpected_indexpages,Costselec,
3535
intrelpages,intreltuples,intindexpages,
3636
intindextuples,boolis_injoin);
37-
externCostcost_sort(List*pathkeys,inttuples,intwidth,boolnoread);
37+
externCostcost_sort(List*pathkeys,inttuples,intwidth);
3838
externCostcost_nestloop(Costoutercost,Costinnercost,intoutertuples,
3939
intinnertuples,intouterpages,boolis_indexjoin);
4040
externCostcost_mergejoin(Costoutercost,Costinnercost,

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp