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

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Centralize att_disbursion readout logic.
This commit is contained in:
Tom Lane
1999-08-09 03:16:47 +00:00
parent 5af4b04f31
commit 14f84cd821
3 changed files with 43 additions and 102 deletions
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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,