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Commit47198b5

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committed
EXCHANGE Cost function improvements begin.
1 parentdec741f commit47198b5

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1 file changed

+55
-7
lines changed

1 file changed

+55
-7
lines changed

‎contrib/pg_exchange/exchange.c

Lines changed: 55 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -37,6 +37,9 @@
3737
#include"partutils.h"
3838
#include"stream.h"
3939

40+
#defineDEFAULT_EXCHANGE_STARTUP_COST100.0
41+
#defineDEFAULT_TRANSFER_TUPLE_COST0.01
42+
4043

4144
staticCustomPathMethodsexchange_path_methods;
4245
staticCustomScanMethodsexchange_plan_methods;
@@ -401,9 +404,13 @@ add_exchange_paths(PlannerInfo *root, RelOptInfo *rel, Index rti, RangeTblEntry
401404
}
402405
}
403406

407+
#include"optimizer/cost.h"
408+
404409
staticvoid
405-
cost_exchange(PlannerInfo*root,RelOptInfo*baserel,Path*path)
410+
cost_exchange(PlannerInfo*root,RelOptInfo*baserel,ExchangePath*expath)
406411
{
412+
Path*subpath;
413+
407414
if (baserel->pages==0&&baserel->tuples==0)
408415
{
409416
baserel->pages=10;
@@ -414,11 +421,53 @@ cost_exchange(PlannerInfo *root, RelOptInfo *baserel, Path *path)
414421

415422
/* Estimate baserel size as best we can with local statistics. */
416423
//set_baserel_size_estimates(root, baserel);
424+
subpath=cstmSubPath1(expath);
425+
expath->cp.path.rows=baserel->tuples;
426+
expath->cp.path.startup_cost=subpath->startup_cost;
427+
switch (expath->mode)
428+
{
429+
caseEXCH_GATHER:
430+
expath->cp.path.startup_cost+=DEFAULT_EXCHANGE_STARTUP_COST;
431+
expath->cp.path.rows=subpath->rows*expath->altrel.nparts;
432+
break;
433+
caseEXCH_STEALTH:
434+
expath->cp.path.rows=subpath->rows;
435+
break;
436+
caseEXCH_BROADCAST:
437+
expath->cp.path.startup_cost+=DEFAULT_EXCHANGE_STARTUP_COST;
438+
expath->cp.path.rows=subpath->rows*expath->altrel.nparts;
439+
break;
440+
caseEXCH_SHUFFLE:
441+
{
442+
doublelocal_rows;
443+
doublereceived_rows;
444+
doublesend_rows;
445+
intinstances;
446+
Path*path=&expath->cp.path;
447+
448+
path->startup_cost+=DEFAULT_EXCHANGE_STARTUP_COST;
449+
path->total_cost+=path->startup_cost;
417450

418-
/* Now I do not want to think about cost estimations. */
419-
path->rows=baserel->tuples;
420-
path->startup_cost=0.1;
421-
path->total_cost=0.1;
451+
/*
452+
* We count on perfect balance of tuple distribution:
453+
* If we have N instances, M tuples from subtree, than we send up to
454+
* local subtree M/N tuples, send to network [M-M/N] tuples and same to
455+
* receive.
456+
*/
457+
path->rows=subpath->rows;
458+
instances=expath->altrel.nparts>0 ?expath->altrel.nparts :2;
459+
send_rows=path->rows- (path->rows/instances);
460+
received_rows=send_rows;
461+
local_rows=path->rows/instances;
462+
path->total_cost+= (send_rows+local_rows)*DEFAULT_CPU_TUPLE_COST;
463+
path->total_cost+= (received_rows)*DEFAULT_CPU_TUPLE_COST*4.;
464+
}
465+
break;
466+
default:
467+
elog(FATAL,"Unknown EXCHANGE mode.");
468+
}
469+
470+
expath->cp.path.total_cost=0.1;
422471
}
423472

424473
/*
@@ -663,8 +712,6 @@ create_exchange_path(PlannerInfo *root, RelOptInfo *rel, Path *children,
663712
pathnode->parallel_workers=0;/* permanently */
664713
pathnode->pathkeys=NIL;
665714

666-
cost_exchange(root,rel,pathnode);/* Change at next step*/
667-
668715
path->flags=0;
669716
/* Contains only one path */
670717
path->custom_paths=lappend(path->custom_paths,children);
@@ -675,6 +722,7 @@ create_exchange_path(PlannerInfo *root, RelOptInfo *rel, Path *children,
675722
memcpy(&epath->altrel,rel,sizeof(RelOptInfo));
676723
epath->exchange_counter=exchange_counter++;
677724
epath->mode=mode;
725+
cost_exchange(root,rel,epath);/* Change at next step*/
678726

679727
returnepath;
680728
}

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