Add hooks to let plugins override the planner's lookups in pg_statistic.
Simon Riggs, with some editorialization by me.
This commit is contained in:
Tom Lane
parent
bc965e840a
commit
7b7df9f0b1
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@ -15,7 +15,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.253 2008/08/25 22:42:34 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.254 2008/09/28 19:51:40 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -119,6 +119,10 @@
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#include "utils/syscache.h"
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/* Hooks for plugins to get control when we ask for stats */
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get_relation_stats_hook_type get_relation_stats_hook = NULL;
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get_index_stats_hook_type get_index_stats_hook = NULL;
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static double var_eq_const(VariableStatData *vardata, Oid operator,
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Datum constval, bool constisnull,
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bool varonleft);
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@ -2935,7 +2939,7 @@ estimate_num_groups(PlannerInfo *root, List *groupExprs, double input_rows)
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* complicated.
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*/
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examine_variable(root, groupexpr, 0, &vardata);
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if (vardata.statsTuple != NULL || vardata.isunique)
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if (HeapTupleIsValid(vardata.statsTuple) || vardata.isunique)
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{
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varinfos = add_unique_group_var(root, varinfos,
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groupexpr, &vardata);
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@ -3942,6 +3946,7 @@ get_join_variables(PlannerInfo *root, List *args, SpecialJoinInfo *sjinfo,
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* subquery, not one in the current query).
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* statsTuple: the pg_statistic entry for the variable, if one exists;
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* otherwise NULL.
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* freefunc: pointer to a function to release statsTuple with.
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* vartype: exposed type of the expression; this should always match
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* the declared input type of the operator we are estimating for.
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* atttype, atttypmod: type data to pass to get_attstatsslot(). This is
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@ -3986,7 +3991,18 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
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rte = root->simple_rte_array[var->varno];
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if (rte->inh)
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if (get_relation_stats_hook &&
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(*get_relation_stats_hook) (root, rte, var->varattno, vardata))
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{
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/*
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* The hook took control of acquiring a stats tuple. If it
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* did supply a tuple, it'd better have supplied a freefunc.
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*/
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if (HeapTupleIsValid(vardata->statsTuple) &&
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!vardata->freefunc)
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elog(ERROR, "no function provided to release variable stats with");
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}
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else if (rte->inh)
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{
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/*
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* XXX This means the Var represents a column of an append
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@ -4000,6 +4016,7 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
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ObjectIdGetDatum(rte->relid),
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Int16GetDatum(var->varattno),
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0, 0);
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vardata->freefunc = ReleaseSysCache;
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}
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else
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{
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@ -4116,10 +4133,28 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
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index->indpred == NIL)
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vardata->isunique = true;
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/* Has it got stats? */
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vardata->statsTuple = SearchSysCache(STATRELATT,
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ObjectIdGetDatum(index->indexoid),
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Int16GetDatum(pos + 1),
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0, 0);
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if (get_index_stats_hook &&
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(*get_index_stats_hook) (root, index->indexoid,
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pos + 1, vardata))
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{
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/*
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* The hook took control of acquiring a stats
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* tuple. If it did supply a tuple, it'd better
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* have supplied a freefunc.
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*/
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if (HeapTupleIsValid(vardata->statsTuple) &&
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!vardata->freefunc)
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elog(ERROR, "no function provided to release variable stats with");
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}
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else
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{
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vardata->statsTuple =
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SearchSysCache(STATRELATT,
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ObjectIdGetDatum(index->indexoid),
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Int16GetDatum(pos + 1),
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0, 0);
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vardata->freefunc = ReleaseSysCache;
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}
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if (vardata->statsTuple)
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break;
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}
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@ -5551,7 +5586,7 @@ btcostestimate(PG_FUNCTION_ARGS)
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double *indexCorrelation = (double *) PG_GETARG_POINTER(7);
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Oid relid;
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AttrNumber colnum;
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HeapTuple tuple;
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VariableStatData vardata;
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double numIndexTuples;
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List *indexBoundQuals;
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int indexcol;
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@ -5756,17 +5791,34 @@ btcostestimate(PG_FUNCTION_ARGS)
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colnum = 1;
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}
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tuple = SearchSysCache(STATRELATT,
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ObjectIdGetDatum(relid),
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Int16GetDatum(colnum),
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0, 0);
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MemSet(&vardata, 0, sizeof(vardata));
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if (HeapTupleIsValid(tuple))
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if (get_index_stats_hook &&
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(*get_index_stats_hook) (root, relid, colnum, &vardata))
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{
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/*
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* The hook took control of acquiring a stats tuple. If it did supply
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* a tuple, it'd better have supplied a freefunc.
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*/
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if (HeapTupleIsValid(vardata.statsTuple) &&
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!vardata.freefunc)
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elog(ERROR, "no function provided to release variable stats with");
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}
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else
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{
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vardata.statsTuple = SearchSysCache(STATRELATT,
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ObjectIdGetDatum(relid),
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Int16GetDatum(colnum),
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0, 0);
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vardata.freefunc = ReleaseSysCache;
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}
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if (HeapTupleIsValid(vardata.statsTuple))
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{
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float4 *numbers;
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int nnumbers;
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if (get_attstatsslot(tuple, InvalidOid, 0,
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if (get_attstatsslot(vardata.statsTuple, InvalidOid, 0,
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STATISTIC_KIND_CORRELATION,
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index->fwdsortop[0],
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NULL, NULL, &numbers, &nnumbers))
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@ -5783,7 +5835,7 @@ btcostestimate(PG_FUNCTION_ARGS)
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free_attstatsslot(InvalidOid, NULL, 0, numbers, nnumbers);
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}
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else if (get_attstatsslot(tuple, InvalidOid, 0,
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else if (get_attstatsslot(vardata.statsTuple, InvalidOid, 0,
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STATISTIC_KIND_CORRELATION,
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index->revsortop[0],
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NULL, NULL, &numbers, &nnumbers))
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@ -5800,9 +5852,10 @@ btcostestimate(PG_FUNCTION_ARGS)
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free_attstatsslot(InvalidOid, NULL, 0, numbers, nnumbers);
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}
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ReleaseSysCache(tuple);
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}
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ReleaseVariableStats(vardata);
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PG_RETURN_VOID();
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}
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/utils/cache/lsyscache.c,v 1.159 2008/08/02 21:32:00 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/utils/cache/lsyscache.c,v 1.160 2008/09/28 19:51:40 tgl Exp $
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*
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* NOTES
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* Eventually, the index information should go through here, too.
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@ -35,6 +35,9 @@
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#include "utils/lsyscache.h"
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#include "utils/syscache.h"
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/* Hook for plugins to get control in get_attavgwidth() */
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get_attavgwidth_hook_type get_attavgwidth_hook = NULL;
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/* ---------- AMOP CACHES ---------- */
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@ -2492,20 +2495,30 @@ get_typmodout(Oid typid)
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*
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* Given the table and attribute number of a column, get the average
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* width of entries in the column. Return zero if no data available.
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*
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* Calling a hook at this point looks somewhat strange, but is required
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* because the optimizer calls this function without any other way for
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* plug-ins to control the result.
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*/
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int32
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get_attavgwidth(Oid relid, AttrNumber attnum)
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{
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HeapTuple tp;
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int32 stawidth;
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if (get_attavgwidth_hook)
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{
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stawidth = (*get_attavgwidth_hook) (relid, attnum);
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if (stawidth > 0)
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return stawidth;
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}
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tp = SearchSysCache(STATRELATT,
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ObjectIdGetDatum(relid),
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Int16GetDatum(attnum),
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0, 0);
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if (HeapTupleIsValid(tp))
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{
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int32 stawidth = ((Form_pg_statistic) GETSTRUCT(tp))->stawidth;
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stawidth = ((Form_pg_statistic) GETSTRUCT(tp))->stawidth;
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ReleaseSysCache(tp);
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if (stawidth > 0)
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return stawidth;
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@ -2523,6 +2536,9 @@ get_attavgwidth(Oid relid, AttrNumber attnum)
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* already-looked-up tuple in the pg_statistic cache. We do this since
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* most callers will want to extract more than one value from the cache
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* entry, and we don't want to repeat the cache lookup unnecessarily.
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* Also, this API allows this routine to be used with statistics tuples
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* that have been provided by a stats hook and didn't really come from
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* pg_statistic.
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*
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* statstuple: pg_statistics tuple to be examined.
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* atttype: type OID of attribute (can be InvalidOid if values == NULL).
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@ -6,7 +6,7 @@
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* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/utils/lsyscache.h,v 1.125 2008/08/02 21:32:01 tgl Exp $
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* $PostgreSQL: pgsql/src/include/utils/lsyscache.h,v 1.126 2008/09/28 19:51:40 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -26,6 +26,10 @@ typedef enum IOFuncSelector
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IOFunc_send
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} IOFuncSelector;
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/* Hook for plugins to get control in get_attavgwidth() */
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typedef int32 (*get_attavgwidth_hook_type) (Oid relid, AttrNumber attnum);
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extern PGDLLIMPORT get_attavgwidth_hook_type get_attavgwidth_hook;
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extern bool op_in_opfamily(Oid opno, Oid opfamily);
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extern int get_op_opfamily_strategy(Oid opno, Oid opfamily);
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extern void get_op_opfamily_properties(Oid opno, Oid opfamily,
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@ -8,7 +8,7 @@
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* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/utils/selfuncs.h,v 1.46 2008/08/16 00:01:38 tgl Exp $
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* $PostgreSQL: pgsql/src/include/utils/selfuncs.h,v 1.47 2008/09/28 19:51:40 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -64,12 +64,13 @@
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/* Return data from examine_variable and friends */
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typedef struct
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typedef struct VariableStatData
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{
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Node *var; /* the Var or expression tree */
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RelOptInfo *rel; /* Relation, or NULL if not identifiable */
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HeapTuple statsTuple; /* pg_statistic tuple, or NULL if none */
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/* NB: if statsTuple!=NULL, it must be freed when caller is done */
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void (*freefunc) (HeapTuple tuple); /* how to free statsTuple */
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Oid vartype; /* exposed type of expression */
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Oid atttype; /* type to pass to get_attstatsslot */
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int32 atttypmod; /* typmod to pass to get_attstatsslot */
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@ -79,7 +80,7 @@ typedef struct
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#define ReleaseVariableStats(vardata) \
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do { \
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if (HeapTupleIsValid((vardata).statsTuple)) \
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ReleaseSysCache((vardata).statsTuple); \
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(* (vardata).freefunc) ((vardata).statsTuple); \
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} while(0)
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@ -97,6 +98,18 @@ typedef enum
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/* selfuncs.c */
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/* Hooks for plugins to get control when we ask for stats */
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typedef bool (*get_relation_stats_hook_type) (PlannerInfo *root,
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RangeTblEntry *rte,
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AttrNumber attnum,
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VariableStatData *vardata);
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extern PGDLLIMPORT get_relation_stats_hook_type get_relation_stats_hook;
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typedef bool (*get_index_stats_hook_type) (PlannerInfo *root,
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Oid indexOid,
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AttrNumber indexattnum,
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VariableStatData *vardata);
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extern PGDLLIMPORT get_index_stats_hook_type get_index_stats_hook;
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extern void examine_variable(PlannerInfo *root, Node *node, int varRelid,
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VariableStatData *vardata);
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extern bool get_restriction_variable(PlannerInfo *root, List *args,
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