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Commit14f84cd

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Store -1 in attdisbursion to signal 'no duplicates in column'.
Centralize att_disbursion readout logic.
1 parent5af4b04 commit14f84cd

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3 files changed

+43
-102
lines changed

3 files changed

+43
-102
lines changed

‎src/backend/commands/vacuum.c‎

Lines changed: 36 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.117 1999/08/08 17:13:10 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.118 1999/08/09 03:16:47 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -2346,36 +2346,46 @@ vc_updstats(Oid relid, int num_pages, int num_tuples, bool hasindex, VRelStats *
23462346
}
23472347
elseif (stats->null_cnt <=1&&stats->best_cnt==1)
23482348
{
2349-
/* looks like we have a unique-key attribute */
2350-
doubletotal= ((double)stats->nonnull_cnt)+ ((double)stats->null_cnt);
2351-
2352-
selratio=1.0 /total;
2353-
}
2354-
elseif (VacAttrStatsLtGtValid(stats)&&stats->min_cnt+stats->max_cnt==stats->nonnull_cnt)
2355-
{
2356-
/* exact result when there are just 1 or 2 values... */
2357-
doublemin_cnt_d=stats->min_cnt,
2358-
max_cnt_d=stats->max_cnt,
2359-
null_cnt_d=stats->null_cnt;
2360-
doubletotal= ((double)stats->nonnull_cnt)+null_cnt_d;
2361-
2362-
selratio= (min_cnt_d*min_cnt_d+max_cnt_d*max_cnt_d+null_cnt_d*null_cnt_d) / (total*total);
2349+
/* looks like we have a unique-key attribute ---
2350+
* flag this with special -1.0 flag value.
2351+
*
2352+
* The correct disbursion is 1.0/numberOfRows, but since
2353+
* the relation row count can get updated without
2354+
* recomputing disbursion, we want to store a "symbolic"
2355+
* value and figure 1.0/numberOfRows on the fly.
2356+
*/
2357+
selratio=-1;
23632358
}
23642359
else
23652360
{
2366-
doublemost= (double) (stats->best_cnt>stats->null_cnt ?stats->best_cnt :stats->null_cnt);
2367-
doubletotal= ((double)stats->nonnull_cnt)+ ((double)stats->null_cnt);
2361+
if (VacAttrStatsLtGtValid(stats)&&
2362+
stats->min_cnt+stats->max_cnt==stats->nonnull_cnt)
2363+
{
2364+
/* exact result when there are just 1 or 2 values... */
2365+
doublemin_cnt_d=stats->min_cnt,
2366+
max_cnt_d=stats->max_cnt,
2367+
null_cnt_d=stats->null_cnt;
2368+
doubletotal= ((double)stats->nonnull_cnt)+null_cnt_d;
23682369

2369-
/*
2370-
* we assume count of other values are 20% of best
2371-
* count in table
2372-
*/
2373-
selratio= (most*most+0.20*most* (total-most)) / (total*total);
2370+
selratio= (min_cnt_d*min_cnt_d+max_cnt_d*max_cnt_d+null_cnt_d*null_cnt_d) / (total*total);
2371+
}
2372+
else
2373+
{
2374+
doublemost= (double) (stats->best_cnt>stats->null_cnt ?stats->best_cnt :stats->null_cnt);
2375+
doubletotal= ((double)stats->nonnull_cnt)+ ((double)stats->null_cnt);
2376+
2377+
/*
2378+
* we assume count of other values are 20% of best
2379+
* count in table
2380+
*/
2381+
selratio= (most*most+0.20*most* (total-most)) / (total*total);
2382+
}
2383+
/* Make sure calculated values are in-range */
2384+
if (selratio<0.0)
2385+
selratio=0.0;
2386+
elseif (selratio>1.0)
2387+
selratio=1.0;
23742388
}
2375-
if (selratio<0.0)
2376-
selratio=0.0;
2377-
elseif (selratio>1.0)
2378-
selratio=1.0;
23792389
attp->attdisbursion=selratio;
23802390

23812391
/*

‎src/backend/optimizer/path/joinpath.c‎

Lines changed: 3 additions & 17 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 1.43 1999/08/06 04:00:15 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.44 1999/08/09 03:16:43 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -23,7 +23,7 @@
2323
#include"optimizer/pathnode.h"
2424
#include"optimizer/paths.h"
2525
#include"parser/parsetree.h"
26-
#include"utils/syscache.h"
26+
#include"utils/lsyscache.h"
2727

2828
staticPath*best_innerjoin(List*join_paths,List*outer_relid);
2929
staticList*sort_inner_and_outer(RelOptInfo*joinrel,RelOptInfo*outerrel,RelOptInfo*innerrel,
@@ -586,7 +586,6 @@ hash_inner_and_outer(Query *root,
586586

587587
/*
588588
* Estimate disbursion of the specified Var
589-
* Generate some kind of estimate, no matter what...
590589
*
591590
* We use a default of 0.1 if we can't figure out anything better.
592591
* This will typically discourage use of a hash rather strongly,
@@ -598,24 +597,11 @@ static Cost
598597
estimate_disbursion(Query*root,Var*var)
599598
{
600599
Oidrelid;
601-
HeapTupleatp;
602-
doubledisbursion;
603600

604601
if (!IsA(var,Var))
605602
return0.1;
606603

607604
relid=getrelid(var->varno,root->rtable);
608605

609-
atp=SearchSysCacheTuple(ATTNUM,
610-
ObjectIdGetDatum(relid),
611-
Int16GetDatum(var->varattno),
612-
0,0);
613-
if (!HeapTupleIsValid(atp))
614-
return0.1;
615-
616-
disbursion= ((Form_pg_attribute)GETSTRUCT(atp))->attdisbursion;
617-
if (disbursion>0.0)
618-
returndisbursion;
619-
620-
return0.1;
606+
return (Cost)get_attdisbursion(relid,var->varattno,0.1);
621607
}

‎src/backend/utils/adt/selfuncs.c‎

Lines changed: 4 additions & 59 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
*
1111
*
1212
* IDENTIFICATION
13-
* $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.37 1999/08/02 02:05:41 tgl Exp $
13+
* $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.38 1999/08/09 03:16:45 tgl Exp $
1414
*
1515
*-------------------------------------------------------------------------
1616
*/
@@ -52,7 +52,6 @@ static bool getattstatistics(Oid relid, AttrNumber attnum,
5252
Datum*commonval,
5353
Datum*loval,
5454
Datum*hival);
55-
staticdoublegetattdisbursion(Oidrelid,AttrNumberattnum);
5655

5756

5857
/*
@@ -172,7 +171,7 @@ eqsel(Oid opid,
172171
/* No VACUUM ANALYZE stats available, so make a guess using
173172
* the disbursion stat (if we have that, which is unlikely...)
174173
*/
175-
selec=getattdisbursion(relid,attno);
174+
selec=get_attdisbursion(relid,attno,0.01);
176175
}
177176

178177
*result= (float64data)selec;
@@ -374,8 +373,8 @@ eqjoinsel(Oid opid,
374373
*result=0.1;
375374
else
376375
{
377-
num1=getattdisbursion(relid1,attno1);
378-
num2=getattdisbursion(relid2,attno2);
376+
num1=get_attdisbursion(relid1,attno1,0.01);
377+
num2=get_attdisbursion(relid2,attno2,0.01);
379378
max= (num1>num2) ?num1 :num2;
380379
if (max <=0)
381380
*result=1.0;
@@ -675,60 +674,6 @@ getattstatistics(Oid relid, AttrNumber attnum, Oid typid, int32 typmod,
675674
return true;
676675
}
677676

678-
/*
679-
* getattdisbursion
680-
* Retrieve the disbursion statistic for an attribute,
681-
* or produce an estimate if no info is available.
682-
*/
683-
staticdouble
684-
getattdisbursion(Oidrelid,AttrNumberattnum)
685-
{
686-
HeapTupleatp;
687-
doubledisbursion;
688-
int32ntuples;
689-
690-
atp=SearchSysCacheTuple(ATTNUM,
691-
ObjectIdGetDatum(relid),
692-
Int16GetDatum(attnum),
693-
0,0);
694-
if (!HeapTupleIsValid(atp))
695-
{
696-
/* this should not happen */
697-
elog(ERROR,"getattdisbursion: no attribute tuple %u %d",
698-
relid,attnum);
699-
return0.1;
700-
}
701-
702-
disbursion= ((Form_pg_attribute)GETSTRUCT(atp))->attdisbursion;
703-
if (disbursion>0.0)
704-
returndisbursion;
705-
706-
/* VACUUM ANALYZE has not stored a disbursion statistic for us.
707-
* Produce an estimate = 1/numtuples. This may produce
708-
* unreasonably small estimates for large tables, so limit
709-
* the estimate to no less than 0.01.
710-
*/
711-
atp=SearchSysCacheTuple(RELOID,
712-
ObjectIdGetDatum(relid),
713-
0,0,0);
714-
if (!HeapTupleIsValid(atp))
715-
{
716-
/* this should not happen */
717-
elog(ERROR,"getattdisbursion: no relation tuple %u",relid);
718-
return0.1;
719-
}
720-
721-
ntuples= ((Form_pg_class)GETSTRUCT(atp))->reltuples;
722-
723-
if (ntuples>0)
724-
disbursion=1.0 / (double)ntuples;
725-
726-
if (disbursion<0.01)
727-
disbursion=0.01;
728-
729-
returndisbursion;
730-
}
731-
732677
float64
733678
btreesel(OidoperatorObjectId,
734679
Oidindrelid,

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