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Store -1 in attdisbursion to signal 'no duplicates in column'.

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Centralize att_disbursion readout logic.
REL7_0_PATCHES
Tom Lane 26 years ago
parent 5af4b04f31
commit 14f84cd821
3 changed files with 43 additions and 102 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 62
      src/backend/commands/vacuum.c
  2. 20
      src/backend/optimizer/path/joinpath.c
  3. 63
      src/backend/utils/adt/selfuncs.c

62
src/backend/commands/vacuum.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.117 1999/08/08 17:13:10 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.118 1999/08/09 03:16:47 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -2346,36 +2346,46 @@ vc_updstats(Oid relid, int num_pages, int num_tuples, bool hasindex, VRelStats *
}
else if (stats->null_cnt <= 1 && stats->best_cnt == 1)
{
/* looks like we have a unique-key attribute */
double total = ((double) stats->nonnull_cnt) + ((double) stats->null_cnt);
selratio = 1.0 / total;
}
else if (VacAttrStatsLtGtValid(stats) && stats->min_cnt + stats->max_cnt == stats->nonnull_cnt)
{
/* exact result when there are just 1 or 2 values... */
double min_cnt_d = stats->min_cnt,
max_cnt_d = stats->max_cnt,
null_cnt_d = stats->null_cnt;
double total = ((double) stats->nonnull_cnt) + null_cnt_d;
selratio = (min_cnt_d * min_cnt_d + max_cnt_d * max_cnt_d + null_cnt_d * null_cnt_d) / (total * total);
/* looks like we have a unique-key attribute ---
* flag this with special -1.0 flag value.
*
* The correct disbursion is 1.0/numberOfRows, but since
* the relation row count can get updated without
* recomputing disbursion, we want to store a "symbolic"
* value and figure 1.0/numberOfRows on the fly.
*/
selratio = -1;
}
else
{
double most = (double) (stats->best_cnt > stats->null_cnt ? stats->best_cnt : stats->null_cnt);
double total = ((double) stats->nonnull_cnt) + ((double) stats->null_cnt);
if (VacAttrStatsLtGtValid(stats) &&
stats->min_cnt + stats->max_cnt == stats->nonnull_cnt)
{
/* exact result when there are just 1 or 2 values... */
double min_cnt_d = stats->min_cnt,
max_cnt_d = stats->max_cnt,
null_cnt_d = stats->null_cnt;
double total = ((double) stats->nonnull_cnt) + null_cnt_d;
/*
* we assume count of other values are 20% of best
* count in table
*/
selratio = (most * most + 0.20 * most * (total - most)) / (total * total);
selratio = (min_cnt_d * min_cnt_d + max_cnt_d * max_cnt_d + null_cnt_d * null_cnt_d) / (total * total);
}
else
{
double most = (double) (stats->best_cnt > stats->null_cnt ? stats->best_cnt : stats->null_cnt);
double total = ((double) stats->nonnull_cnt) + ((double) stats->null_cnt);
/*
* we assume count of other values are 20% of best
* count in table
*/
selratio = (most * most + 0.20 * most * (total - most)) / (total * total);
}
/* Make sure calculated values are in-range */
if (selratio < 0.0)
selratio = 0.0;
else if (selratio > 1.0)
selratio = 1.0;
}
if (selratio < 0.0)
selratio = 0.0;
else if (selratio > 1.0)
selratio = 1.0;
attp->attdisbursion = selratio;
/*

20
src/backend/optimizer/path/joinpath.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.43 1999/08/06 04:00:15 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.44 1999/08/09 03:16:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -23,7 +23,7 @@
#include "optimizer/pathnode.h"
#include "optimizer/paths.h"
#include "parser/parsetree.h"
#include "utils/syscache.h"
#include "utils/lsyscache.h"
static Path *best_innerjoin(List *join_paths, List *outer_relid);
static List *sort_inner_and_outer(RelOptInfo *joinrel, RelOptInfo *outerrel, RelOptInfo *innerrel,
@ -586,7 +586,6 @@ hash_inner_and_outer(Query *root,
/*
* Estimate disbursion of the specified Var
* Generate some kind of estimate, no matter what...
*
* We use a default of 0.1 if we can't figure out anything better.
* This will typically discourage use of a hash rather strongly,
@ -598,24 +597,11 @@ static Cost
estimate_disbursion(Query *root, Var *var)
{
Oid relid;
HeapTuple atp;
double disbursion;
if (! IsA(var, Var))
return 0.1;
relid = getrelid(var->varno, root->rtable);
atp = SearchSysCacheTuple(ATTNUM,
ObjectIdGetDatum(relid),
Int16GetDatum(var->varattno),
0, 0);
if (! HeapTupleIsValid(atp))
return 0.1;
disbursion = ((Form_pg_attribute) GETSTRUCT(atp))->attdisbursion;
if (disbursion > 0.0)
return disbursion;
return 0.1;
return (Cost) get_attdisbursion(relid, var->varattno, 0.1);
}

63
src/backend/utils/adt/selfuncs.c
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@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.37 1999/08/02 02:05:41 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.38 1999/08/09 03:16:45 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -52,7 +52,6 @@ static bool getattstatistics(Oid relid, AttrNumber attnum,
Datum *commonval,
Datum *loval,
Datum *hival);
static double getattdisbursion(Oid relid, AttrNumber attnum);
/*
@ -172,7 +171,7 @@ eqsel(Oid opid,
/* No VACUUM ANALYZE stats available, so make a guess using
* the disbursion stat (if we have that, which is unlikely...)
*/
selec = getattdisbursion(relid, attno);
selec = get_attdisbursion(relid, attno, 0.01);
}
*result = (float64data) selec;
@ -374,8 +373,8 @@ eqjoinsel(Oid opid,
*result = 0.1;
else
{
num1 = getattdisbursion(relid1, attno1);
num2 = getattdisbursion(relid2, attno2);
num1 = get_attdisbursion(relid1, attno1, 0.01);
num2 = get_attdisbursion(relid2, attno2, 0.01);
max = (num1 > num2) ? num1 : num2;
if (max <= 0)
*result = 1.0;
@ -675,60 +674,6 @@ getattstatistics(Oid relid, AttrNumber attnum, Oid typid, int32 typmod,
return true;
}
/*
* getattdisbursion
* Retrieve the disbursion statistic for an attribute,
* or produce an estimate if no info is available.
*/
static double
getattdisbursion(Oid relid, AttrNumber attnum)
{
HeapTuple atp;
double disbursion;
int32 ntuples;
atp = SearchSysCacheTuple(ATTNUM,
ObjectIdGetDatum(relid),
Int16GetDatum(attnum),
0, 0);
if (!HeapTupleIsValid(atp))
{
/* this should not happen */
elog(ERROR, "getattdisbursion: no attribute tuple %u %d",
relid, attnum);
return 0.1;
}
disbursion = ((Form_pg_attribute) GETSTRUCT(atp))->attdisbursion;
if (disbursion > 0.0)
return disbursion;
/* VACUUM ANALYZE has not stored a disbursion statistic for us.
* Produce an estimate = 1/numtuples. This may produce
* unreasonably small estimates for large tables, so limit
* the estimate to no less than 0.01.
*/
atp = SearchSysCacheTuple(RELOID,
ObjectIdGetDatum(relid),
0, 0, 0);
if (!HeapTupleIsValid(atp))
{
/* this should not happen */
elog(ERROR, "getattdisbursion: no relation tuple %u", relid);
return 0.1;
}
ntuples = ((Form_pg_class) GETSTRUCT(atp))->reltuples;
if (ntuples > 0)
disbursion = 1.0 / (double) ntuples;
if (disbursion < 0.01)
disbursion = 0.01;
return disbursion;
}
float64
btreesel(Oid operatorObjectId,
Oid indrelid,

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