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Add hooks to let plugins override the planner's lookups in pg_statistic.

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Simon Riggs, with some editorialization by me.
This commit is contained in:
Tom Lane
2008-09-28 19:51:40 +00:00
parent bc965e840a
commit 7b7df9f0b1
4 changed files with 109 additions and 23 deletions
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85
src/backend/utils/adt/selfuncs.c
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@ -15,7 +15,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.253 2008/08/25 22:42:34 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.254 2008/09/28 19:51:40 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -119,6 +119,10 @@
#include "utils/syscache.h"
/* Hooks for plugins to get control when we ask for stats */
get_relation_stats_hook_type get_relation_stats_hook = NULL;
get_index_stats_hook_type get_index_stats_hook = NULL;
static double var_eq_const(VariableStatData *vardata, Oid operator,
Datum constval, bool constisnull,
bool varonleft);
@ -2935,7 +2939,7 @@ estimate_num_groups(PlannerInfo *root, List *groupExprs, double input_rows)
* complicated.
*/
examine_variable(root, groupexpr, 0, &vardata);
if (vardata.statsTuple != NULL || vardata.isunique)
if (HeapTupleIsValid(vardata.statsTuple) || vardata.isunique)
{
varinfos = add_unique_group_var(root, varinfos,
groupexpr, &vardata);
@ -3942,6 +3946,7 @@ get_join_variables(PlannerInfo *root, List *args, SpecialJoinInfo *sjinfo,
* subquery, not one in the current query).
* statsTuple: the pg_statistic entry for the variable, if one exists;
* otherwise NULL.
* freefunc: pointer to a function to release statsTuple with.
* vartype: exposed type of the expression; this should always match
* the declared input type of the operator we are estimating for.
* atttype, atttypmod: type data to pass to get_attstatsslot(). This is
@ -3986,7 +3991,18 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
rte = root->simple_rte_array[var->varno];
if (rte->inh)
if (get_relation_stats_hook &&
(*get_relation_stats_hook) (root, rte, var->varattno, vardata))
{
/*
* The hook took control of acquiring a stats tuple. If it
* did supply a tuple, it'd better have supplied a freefunc.
*/
if (HeapTupleIsValid(vardata->statsTuple) &&
!vardata->freefunc)
elog(ERROR, "no function provided to release variable stats with");
}
else if (rte->inh)
{
/*
* XXX This means the Var represents a column of an append
@ -4000,6 +4016,7 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
ObjectIdGetDatum(rte->relid),
Int16GetDatum(var->varattno),
0, 0);
vardata->freefunc = ReleaseSysCache;
}
else
{
@ -4116,10 +4133,28 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
index->indpred == NIL)
vardata->isunique = true;
/* Has it got stats? */
vardata->statsTuple = SearchSysCache(STATRELATT,
ObjectIdGetDatum(index->indexoid),
Int16GetDatum(pos + 1),
0, 0);
if (get_index_stats_hook &&
(*get_index_stats_hook) (root, index->indexoid,
pos + 1, vardata))
{
/*
* The hook took control of acquiring a stats
* tuple. If it did supply a tuple, it'd better
* have supplied a freefunc.
*/
if (HeapTupleIsValid(vardata->statsTuple) &&
!vardata->freefunc)
elog(ERROR, "no function provided to release variable stats with");
}
else
{
vardata->statsTuple =
SearchSysCache(STATRELATT,
ObjectIdGetDatum(index->indexoid),
Int16GetDatum(pos + 1),
0, 0);
vardata->freefunc = ReleaseSysCache;
}
if (vardata->statsTuple)
break;
}
@ -5551,7 +5586,7 @@ btcostestimate(PG_FUNCTION_ARGS)
double *indexCorrelation = (double *) PG_GETARG_POINTER(7);
Oid relid;
AttrNumber colnum;
HeapTuple tuple;
VariableStatData vardata;
double numIndexTuples;
List *indexBoundQuals;
int indexcol;
@ -5756,17 +5791,34 @@ btcostestimate(PG_FUNCTION_ARGS)
colnum = 1;
}
tuple = SearchSysCache(STATRELATT,
ObjectIdGetDatum(relid),
Int16GetDatum(colnum),
0, 0);
MemSet(&vardata, 0, sizeof(vardata));
if (HeapTupleIsValid(tuple))
if (get_index_stats_hook &&
(*get_index_stats_hook) (root, relid, colnum, &vardata))
{
/*
* The hook took control of acquiring a stats tuple. If it did supply
* a tuple, it'd better have supplied a freefunc.
*/
if (HeapTupleIsValid(vardata.statsTuple) &&
!vardata.freefunc)
elog(ERROR, "no function provided to release variable stats with");
}
else
{
vardata.statsTuple = SearchSysCache(STATRELATT,
ObjectIdGetDatum(relid),
Int16GetDatum(colnum),
0, 0);
vardata.freefunc = ReleaseSysCache;
}
if (HeapTupleIsValid(vardata.statsTuple))
{
float4 *numbers;
int nnumbers;
if (get_attstatsslot(tuple, InvalidOid, 0,
if (get_attstatsslot(vardata.statsTuple, InvalidOid, 0,
STATISTIC_KIND_CORRELATION,
index->fwdsortop[0],
NULL, NULL, &numbers, &nnumbers))
@ -5783,7 +5835,7 @@ btcostestimate(PG_FUNCTION_ARGS)
free_attstatsslot(InvalidOid, NULL, 0, numbers, nnumbers);
}
else if (get_attstatsslot(tuple, InvalidOid, 0,
else if (get_attstatsslot(vardata.statsTuple, InvalidOid, 0,
STATISTIC_KIND_CORRELATION,
index->revsortop[0],
NULL, NULL, &numbers, &nnumbers))
@ -5800,9 +5852,10 @@ btcostestimate(PG_FUNCTION_ARGS)
free_attstatsslot(InvalidOid, NULL, 0, numbers, nnumbers);
}
ReleaseSysCache(tuple);
}
ReleaseVariableStats(vardata);
PG_RETURN_VOID();
}