mirror of https://github.com/postgres/postgres
This function is able to clear the data associated to an extended
statistics object, making things so as the object looks as
newly-created.
The caller of this function needs the following arguments for the
extended stats to clear:
- The name of the relation.
- The schema name of the relation.
- The name of the extended stats object.
- The schema name of the extended stats object.
- If the stats are inherited or not.
The first two parameters are especially important to ensure a consistent
lookup and ACL checks for the relation on which is based the extended
stats object that will be cleared, relying first on a RangeVar lookup
where permissions are checked without locking a relation, critical to
prevent denial-of-service attacks when using this kind of function (see
also 688dc6299a for a similar concern). The third to fifth arguments
give a way to target the extended stats records to clear.
This has been extracted from a larger patch by the same author, for a
piece which is again useful on its own. I have rewritten large portions
of it. The tests have been extended while discussing this piece,
resulting on what this commit includes. The intention behind this
feature is to add support for the import of extended statistics across
dumps and upgrades, this change building one piece that we will be able
to rely on for the rest of the changes.
Bump catalog version.
Author: Corey Huinker <corey.huinker@gmail.com>
Co-authored-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://postgr.es/m/CADkLM=dpz3KFnqP-dgJ-zvRvtjsa8UZv8wDAQdqho=qN3kX0Zg@mail.gmail.com
pull/269/head
Michael Paquier
4 months ago
parent
d40fd85187
commit
d756fa1019
@ -0,0 +1,232 @@ |
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/*-------------------------------------------------------------------------
|
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* |
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* extended_stats_funcs.c |
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* Functions for manipulating extended statistics. |
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* |
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* This file includes the set of facilities required to support the direct |
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* manipulations of extended statistics objects. |
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* |
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* Portions Copyright (c) 1996-2026, 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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* IDENTIFICATION |
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* src/backend/statistics/extended_stats_funcs.c |
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* |
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*------------------------------------------------------------------------- |
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*/ |
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#include "postgres.h" |
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#include "access/heapam.h" |
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#include "catalog/indexing.h" |
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#include "catalog/namespace.h" |
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#include "catalog/pg_database.h" |
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#include "catalog/pg_statistic_ext.h" |
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#include "catalog/pg_statistic_ext_data.h" |
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#include "miscadmin.h" |
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#include "nodes/makefuncs.h" |
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#include "statistics/stat_utils.h" |
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#include "utils/acl.h" |
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#include "utils/builtins.h" |
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#include "utils/fmgroids.h" |
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#include "utils/lsyscache.h" |
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#include "utils/syscache.h" |
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/*
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* Index of the arguments for the SQL functions. |
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*/ |
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enum extended_stats_argnum |
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{ |
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RELSCHEMA_ARG = 0, |
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RELNAME_ARG, |
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STATSCHEMA_ARG, |
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STATNAME_ARG, |
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INHERITED_ARG, |
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NUM_EXTENDED_STATS_ARGS, |
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}; |
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|
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/*
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* The argument names and type OIDs of the arguments for the SQL |
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* functions. |
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*/ |
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static struct StatsArgInfo extarginfo[] = |
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{ |
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[RELSCHEMA_ARG] = {"schemaname", TEXTOID}, |
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[RELNAME_ARG] = {"relname", TEXTOID}, |
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[STATSCHEMA_ARG] = {"statistics_schemaname", TEXTOID}, |
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[STATNAME_ARG] = {"statistics_name", TEXTOID}, |
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[INHERITED_ARG] = {"inherited", BOOLOID}, |
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[NUM_EXTENDED_STATS_ARGS] = {0}, |
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}; |
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static HeapTuple get_pg_statistic_ext(Relation pg_stext, Oid nspoid, |
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const char *stxname); |
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static bool delete_pg_statistic_ext_data(Oid stxoid, bool inherited); |
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/*
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* Fetch a pg_statistic_ext row by name and namespace OID. |
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*/ |
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static HeapTuple |
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get_pg_statistic_ext(Relation pg_stext, Oid nspoid, const char *stxname) |
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{ |
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ScanKeyData key[2]; |
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SysScanDesc scan; |
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HeapTuple tup; |
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Oid stxoid = InvalidOid; |
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ScanKeyInit(&key[0], |
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Anum_pg_statistic_ext_stxname, |
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BTEqualStrategyNumber, |
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F_NAMEEQ, |
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CStringGetDatum(stxname)); |
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ScanKeyInit(&key[1], |
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Anum_pg_statistic_ext_stxnamespace, |
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BTEqualStrategyNumber, |
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F_OIDEQ, |
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ObjectIdGetDatum(nspoid)); |
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/*
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* Try to find matching pg_statistic_ext row. |
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*/ |
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scan = systable_beginscan(pg_stext, |
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StatisticExtNameIndexId, |
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true, |
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NULL, |
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2, |
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key); |
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/* Lookup is based on a unique index, so we get either 0 or 1 tuple. */ |
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tup = systable_getnext(scan); |
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if (HeapTupleIsValid(tup)) |
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stxoid = ((Form_pg_statistic_ext) GETSTRUCT(tup))->oid; |
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systable_endscan(scan); |
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if (!OidIsValid(stxoid)) |
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return NULL; |
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return SearchSysCacheCopy1(STATEXTOID, ObjectIdGetDatum(stxoid)); |
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} |
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/*
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* Remove an existing pg_statistic_ext_data row for a given pg_statistic_ext |
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* row and "inherited" pair. |
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*/ |
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static bool |
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delete_pg_statistic_ext_data(Oid stxoid, bool inherited) |
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{ |
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Relation sed = table_open(StatisticExtDataRelationId, RowExclusiveLock); |
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HeapTuple oldtup; |
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bool result = false; |
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/* Is there already a pg_statistic tuple for this attribute? */ |
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oldtup = SearchSysCache2(STATEXTDATASTXOID, |
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ObjectIdGetDatum(stxoid), |
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BoolGetDatum(inherited)); |
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if (HeapTupleIsValid(oldtup)) |
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{ |
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CatalogTupleDelete(sed, &oldtup->t_self); |
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ReleaseSysCache(oldtup); |
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result = true; |
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} |
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table_close(sed, RowExclusiveLock); |
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CommandCounterIncrement(); |
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return result; |
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} |
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/*
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* Delete statistics for the given statistics object. |
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*/ |
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Datum |
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pg_clear_extended_stats(PG_FUNCTION_ARGS) |
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{ |
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char *relnspname; |
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char *relname; |
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char *nspname; |
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Oid nspoid; |
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Oid relid; |
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char *stxname; |
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bool inherited; |
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Relation pg_stext; |
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HeapTuple tup; |
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Form_pg_statistic_ext stxform; |
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Oid locked_table = InvalidOid; |
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/* relation arguments */ |
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stats_check_required_arg(fcinfo, extarginfo, RELSCHEMA_ARG); |
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relnspname = TextDatumGetCString(PG_GETARG_DATUM(RELSCHEMA_ARG)); |
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stats_check_required_arg(fcinfo, extarginfo, RELNAME_ARG); |
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relname = TextDatumGetCString(PG_GETARG_DATUM(RELNAME_ARG)); |
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/* extended statistics arguments */ |
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stats_check_required_arg(fcinfo, extarginfo, STATSCHEMA_ARG); |
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nspname = TextDatumGetCString(PG_GETARG_DATUM(STATSCHEMA_ARG)); |
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stats_check_required_arg(fcinfo, extarginfo, STATNAME_ARG); |
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stxname = TextDatumGetCString(PG_GETARG_DATUM(STATNAME_ARG)); |
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stats_check_required_arg(fcinfo, extarginfo, INHERITED_ARG); |
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inherited = PG_GETARG_BOOL(INHERITED_ARG); |
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if (RecoveryInProgress()) |
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{ |
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ereport(WARNING, |
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errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), |
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errmsg("recovery is in progress"), |
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errhint("Statistics cannot be modified during recovery.")); |
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PG_RETURN_VOID(); |
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} |
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/*
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* First open the relation where we expect to find the statistics. This |
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* is similar to relation and attribute statistics, so as ACL checks are |
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* done before any locks are taken, even before any attempts related to |
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* the extended stats object. |
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*/ |
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relid = RangeVarGetRelidExtended(makeRangeVar(relnspname, relname, -1), |
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ShareUpdateExclusiveLock, 0, |
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RangeVarCallbackForStats, &locked_table); |
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/* Now check if the namespace of the stats object exists. */ |
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nspoid = get_namespace_oid(nspname, true); |
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if (nspoid == InvalidOid) |
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{ |
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ereport(WARNING, |
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errcode(ERRCODE_UNDEFINED_OBJECT), |
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errmsg("could not find schema \"%s\"", nspname)); |
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PG_RETURN_VOID(); |
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} |
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pg_stext = table_open(StatisticExtRelationId, RowExclusiveLock); |
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tup = get_pg_statistic_ext(pg_stext, nspoid, stxname); |
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if (!HeapTupleIsValid(tup)) |
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{ |
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table_close(pg_stext, RowExclusiveLock); |
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ereport(WARNING, |
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errcode(ERRCODE_UNDEFINED_OBJECT), |
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errmsg("could not find extended statistics object \"%s\".\"%s\"", |
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nspname, stxname)); |
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PG_RETURN_VOID(); |
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} |
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stxform = (Form_pg_statistic_ext) GETSTRUCT(tup); |
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/*
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* This should be consistent, based on the lock taken on the table when we |
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* started. |
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*/ |
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if (stxform->stxrelid != relid) |
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elog(ERROR, "cache lookup failed for extended stats %u: found relation %u but expected %u", |
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stxform->oid, stxform->stxrelid, relid); |
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delete_pg_statistic_ext_data(stxform->oid, inherited); |
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heap_freetuple(tup); |
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table_close(pg_stext, RowExclusiveLock); |
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PG_RETURN_VOID(); |
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} |
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