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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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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);
}