database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-16 06:01:02 +03:00
Code Activity

First cut at making indexscan cost estimates depend on correlation

Browse Source 
between index order and table order.
This commit is contained in:
Tom Lane
2001-05-09 23:13:37 +00:00
parent e02033572d
commit c23bc6fbb0
8 changed files with 317 additions and 88 deletions
Download Patch File Download Diff File Expand all files Collapse all files

137
src/backend/utils/adt/selfuncs.c
View File

@ -15,7 +15,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.88 2001/05/07 00:43:23 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.89 2001/05/09 23:13:35 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -39,6 +39,7 @@
#include "optimizer/cost.h"
#include "parser/parse_func.h"
#include "parser/parse_oper.h"
#include "parser/parsetree.h"
#include "utils/builtins.h"
#include "utils/date.h"
#include "utils/int8.h"
@ -818,7 +819,6 @@ eqjoinsel(PG_FUNCTION_ARGS)
{
#ifdef NOT_USED /* see neqjoinsel() before removing me! */
Oid opid = PG_GETARG_OID(0);
#endif
Oid relid1 = PG_GETARG_OID(1);
AttrNumber attno1 = PG_GETARG_INT16(2);
@ -2230,16 +2230,14 @@ string_to_datum(const char *str, Oid datatype)
*-------------------------------------------------------------------------
*/
static Datum
genericcostestimate(PG_FUNCTION_ARGS)
static void
genericcostestimate(Query *root, RelOptInfo *rel,
IndexOptInfo *index, List *indexQuals,
Cost *indexStartupCost,
Cost *indexTotalCost,
Selectivity *indexSelectivity,
double *indexCorrelation)
{
Query *root = (Query *) PG_GETARG_POINTER(0);
RelOptInfo *rel = (RelOptInfo *) PG_GETARG_POINTER(1);
IndexOptInfo *index = (IndexOptInfo *) PG_GETARG_POINTER(2);
List *indexQuals = (List *) PG_GETARG_POINTER(3);
Cost *indexStartupCost = (Cost *) PG_GETARG_POINTER(4);
Cost *indexTotalCost = (Cost *) PG_GETARG_POINTER(5);
Selectivity *indexSelectivity = (Selectivity *) PG_GETARG_POINTER(6);
double numIndexTuples;
double numIndexPages;
@ -2275,33 +2273,134 @@ genericcostestimate(PG_FUNCTION_ARGS)
*indexTotalCost = numIndexPages +
(cpu_index_tuple_cost + cost_qual_eval(indexQuals)) * numIndexTuples;
PG_RETURN_VOID();
/*
* Generic assumption about index correlation: there isn't any.
*/
*indexCorrelation = 0.0;
}
/*
* For first cut, just use generic function for all index types.
*/
Datum
btcostestimate(PG_FUNCTION_ARGS)
{
return genericcostestimate(fcinfo);
Query *root = (Query *) PG_GETARG_POINTER(0);
RelOptInfo *rel = (RelOptInfo *) PG_GETARG_POINTER(1);
IndexOptInfo *index = (IndexOptInfo *) PG_GETARG_POINTER(2);
List *indexQuals = (List *) PG_GETARG_POINTER(3);
Cost *indexStartupCost = (Cost *) PG_GETARG_POINTER(4);
Cost *indexTotalCost = (Cost *) PG_GETARG_POINTER(5);
Selectivity *indexSelectivity = (Selectivity *) PG_GETARG_POINTER(6);
double *indexCorrelation = (double *) PG_GETARG_POINTER(7);
genericcostestimate(root, rel, index, indexQuals,
indexStartupCost, indexTotalCost,
indexSelectivity, indexCorrelation);
/*
* If it's a functional index, leave the default zero-correlation
* estimate in place. If not, and if we can get an estimate for
* the first variable's ordering correlation C from pg_statistic,
* estimate the index correlation as C / number-of-columns.
* (The idea here is that multiple columns dilute the importance
* of the first column's ordering, but don't negate it entirely.)
*/
if (index->indproc == InvalidOid)
{
Oid relid;
HeapTuple tuple;
relid = getrelid(lfirsti(rel->relids), root->rtable);
Assert(relid != InvalidOid);
tuple = SearchSysCache(STATRELATT,
ObjectIdGetDatum(relid),
Int16GetDatum(index->indexkeys[0]),
0, 0);
if (HeapTupleIsValid(tuple))
{
Oid typid;
int32 typmod;
float4 *numbers;
int nnumbers;
get_atttypetypmod(relid, index->indexkeys[0],
&typid, &typmod);
if (get_attstatsslot(tuple, typid, typmod,
STATISTIC_KIND_CORRELATION,
index->ordering[0],
NULL, NULL, &numbers, &nnumbers))
{
double varCorrelation;
int nKeys;
Assert(nnumbers == 1);
varCorrelation = numbers[0];
for (nKeys = 1; index->indexkeys[nKeys] != 0; nKeys++)
/*skip*/;
*indexCorrelation = varCorrelation / nKeys;
free_attstatsslot(typid, NULL, 0, numbers, nnumbers);
}
ReleaseSysCache(tuple);
}
}
PG_RETURN_VOID();
}
Datum
rtcostestimate(PG_FUNCTION_ARGS)
{
return genericcostestimate(fcinfo);
Query *root = (Query *) PG_GETARG_POINTER(0);
RelOptInfo *rel = (RelOptInfo *) PG_GETARG_POINTER(1);
IndexOptInfo *index = (IndexOptInfo *) PG_GETARG_POINTER(2);
List *indexQuals = (List *) PG_GETARG_POINTER(3);
Cost *indexStartupCost = (Cost *) PG_GETARG_POINTER(4);
Cost *indexTotalCost = (Cost *) PG_GETARG_POINTER(5);
Selectivity *indexSelectivity = (Selectivity *) PG_GETARG_POINTER(6);
double *indexCorrelation = (double *) PG_GETARG_POINTER(7);
genericcostestimate(root, rel, index, indexQuals,
indexStartupCost, indexTotalCost,
indexSelectivity, indexCorrelation);
PG_RETURN_VOID();
}
Datum
hashcostestimate(PG_FUNCTION_ARGS)
{
return genericcostestimate(fcinfo);
Query *root = (Query *) PG_GETARG_POINTER(0);
RelOptInfo *rel = (RelOptInfo *) PG_GETARG_POINTER(1);
IndexOptInfo *index = (IndexOptInfo *) PG_GETARG_POINTER(2);
List *indexQuals = (List *) PG_GETARG_POINTER(3);
Cost *indexStartupCost = (Cost *) PG_GETARG_POINTER(4);
Cost *indexTotalCost = (Cost *) PG_GETARG_POINTER(5);
Selectivity *indexSelectivity = (Selectivity *) PG_GETARG_POINTER(6);
double *indexCorrelation = (double *) PG_GETARG_POINTER(7);
genericcostestimate(root, rel, index, indexQuals,
indexStartupCost, indexTotalCost,
indexSelectivity, indexCorrelation);
PG_RETURN_VOID();
}
Datum
gistcostestimate(PG_FUNCTION_ARGS)
{
return genericcostestimate(fcinfo);
Query *root = (Query *) PG_GETARG_POINTER(0);
RelOptInfo *rel = (RelOptInfo *) PG_GETARG_POINTER(1);
IndexOptInfo *index = (IndexOptInfo *) PG_GETARG_POINTER(2);
List *indexQuals = (List *) PG_GETARG_POINTER(3);
Cost *indexStartupCost = (Cost *) PG_GETARG_POINTER(4);
Cost *indexTotalCost = (Cost *) PG_GETARG_POINTER(5);
Selectivity *indexSelectivity = (Selectivity *) PG_GETARG_POINTER(6);
double *indexCorrelation = (double *) PG_GETARG_POINTER(7);
genericcostestimate(root, rel, index, indexQuals,
indexStartupCost, indexTotalCost,
indexSelectivity, indexCorrelation);
PG_RETURN_VOID();
}