relation_stats.c

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/*-------------------------------------------------------------------------
 * relation_stats.c
 *
 *    PostgreSQL relation statistics manipulation
 *
 * Code supporting the direct import of relation statistics, similar to
 * what is done by the ANALYZE command.
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *       src/backend/statistics/relation_stats.c
 *
 *-------------------------------------------------------------------------
 */
 
#include "postgres.h"
 
#include "access/heapam.h"
#include "catalog/indexing.h"
#include "statistics/stat_utils.h"
#include "utils/fmgroids.h"
#include "utils/fmgrprotos.h"
#include "utils/syscache.h"
 
 
/*
 * Positional argument numbers, names, and types for
 * relation_statistics_update().
 */
 
enum relation_stats_argnum
{
    RELATION_ARG = 0,
    RELPAGES_ARG,
    RELTUPLES_ARG,
    RELALLVISIBLE_ARG,
    RELALLFROZEN_ARG,
    NUM_RELATION_STATS_ARGS
};
 
static struct StatsArgInfo relarginfo[] =
{
    [RELATION_ARG] = {"relation", REGCLASSOID},
    [RELPAGES_ARG] = {"relpages", INT4OID},
    [RELTUPLES_ARG] = {"reltuples", FLOAT4OID},
    [RELALLVISIBLE_ARG] = {"relallvisible", INT4OID},
    [RELALLFROZEN_ARG] = {"relallfrozen", INT4OID},
    [NUM_RELATION_STATS_ARGS] = {0}
};
 
static bool relation_statistics_update(FunctionCallInfo fcinfo);
 
/*
 * Internal function for modifying statistics for a relation.
 */
static bool
relation_statistics_update(FunctionCallInfo fcinfo)
{
    bool        result = true;
    Oid         reloid;
    Relation    crel;
    BlockNumber relpages = 0;
    bool        update_relpages = false;
    float       reltuples = 0;
    bool        update_reltuples = false;
    BlockNumber relallvisible = 0;
    bool        update_relallvisible = false;
    BlockNumber relallfrozen = 0;
    bool        update_relallfrozen = false;
    HeapTuple   ctup;
    Form_pg_class pgcform;
    int         replaces[4] = {0};
    Datum       values[4] = {0};
    bool        nulls[4] = {0};
    int         nreplaces = 0;
 
    if (!PG_ARGISNULL(RELPAGES_ARG))
    {
        relpages = PG_GETARG_UINT32(RELPAGES_ARG);
        update_relpages = true;
    }
 
    if (!PG_ARGISNULL(RELTUPLES_ARG))
    {
        reltuples = PG_GETARG_FLOAT4(RELTUPLES_ARG);
        if (reltuples < -1.0)
        {
            ereport(WARNING,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("reltuples cannot be < -1.0")));
            result = false;
        }
        else
            update_reltuples = true;
    }
 
    if (!PG_ARGISNULL(RELALLVISIBLE_ARG))
    {
        relallvisible = PG_GETARG_UINT32(RELALLVISIBLE_ARG);
        update_relallvisible = true;
    }
 
    if (!PG_ARGISNULL(RELALLFROZEN_ARG))
    {
        relallfrozen = PG_GETARG_UINT32(RELALLFROZEN_ARG);
        update_relallfrozen = true;
    }
 
    stats_check_required_arg(fcinfo, relarginfo, RELATION_ARG);
    reloid = PG_GETARG_OID(RELATION_ARG);
 
    if (RecoveryInProgress())
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("recovery is in progress"),
                 errhint("Statistics cannot be modified during recovery.")));
 
    stats_lock_check_privileges(reloid);
 
    /*
     * Take RowExclusiveLock on pg_class, consistent with
     * vac_update_relstats().
     */
    crel = table_open(RelationRelationId, RowExclusiveLock);
 
    ctup = SearchSysCache1(RELOID, ObjectIdGetDatum(reloid));
    if (!HeapTupleIsValid(ctup))
        elog(ERROR, "pg_class entry for relid %u not found", reloid);
 
    pgcform = (Form_pg_class) GETSTRUCT(ctup);
 
    if (update_relpages && relpages != pgcform->relpages)
    {
        replaces[nreplaces] = Anum_pg_class_relpages;
        values[nreplaces] = UInt32GetDatum(relpages);
        nreplaces++;
    }
 
    if (update_reltuples && reltuples != pgcform->reltuples)
    {
        replaces[nreplaces] = Anum_pg_class_reltuples;
        values[nreplaces] = Float4GetDatum(reltuples);
        nreplaces++;
    }
 
    if (update_relallvisible && relallvisible != pgcform->relallvisible)
    {
        replaces[nreplaces] = Anum_pg_class_relallvisible;
        values[nreplaces] = UInt32GetDatum(relallvisible);
        nreplaces++;
    }
 
    if (update_relallfrozen && relallfrozen != pgcform->relallfrozen)
    {
        replaces[nreplaces] = Anum_pg_class_relallfrozen;
        values[nreplaces] = UInt32GetDatum(relallfrozen);
        nreplaces++;
    }
 
    if (nreplaces > 0)
    {
        TupleDesc   tupdesc = RelationGetDescr(crel);
        HeapTuple   newtup;
 
        newtup = heap_modify_tuple_by_cols(ctup, tupdesc, nreplaces,
                                           replaces, values, nulls);
        CatalogTupleUpdate(crel, &newtup->t_self, newtup);
        heap_freetuple(newtup);
    }
 
    ReleaseSysCache(ctup);
 
    /* release the lock, consistent with vac_update_relstats() */
    table_close(crel, RowExclusiveLock);
 
    CommandCounterIncrement();
 
    return result;
}
 
/*
 * Clear statistics for a given pg_class entry; that is, set back to initial
 * stats for a newly-created table.
 */
Datum
pg_clear_relation_stats(PG_FUNCTION_ARGS)
{
    LOCAL_FCINFO(newfcinfo, 5);
 
    InitFunctionCallInfoData(*newfcinfo, NULL, 5, InvalidOid, NULL, NULL);
 
    newfcinfo->args[0].value = PG_GETARG_OID(0);
    newfcinfo->args[0].isnull = PG_ARGISNULL(0);
    newfcinfo->args[1].value = UInt32GetDatum(0);
    newfcinfo->args[1].isnull = false;
    newfcinfo->args[2].value = Float4GetDatum(-1.0);
    newfcinfo->args[2].isnull = false;
    newfcinfo->args[3].value = UInt32GetDatum(0);
    newfcinfo->args[3].isnull = false;
    newfcinfo->args[4].value = UInt32GetDatum(0);
    newfcinfo->args[4].isnull = false;
 
    relation_statistics_update(newfcinfo);
    PG_RETURN_VOID();
}
 
Datum
pg_restore_relation_stats(PG_FUNCTION_ARGS)
{
    LOCAL_FCINFO(positional_fcinfo, NUM_RELATION_STATS_ARGS);
    bool        result = true;
 
    InitFunctionCallInfoData(*positional_fcinfo, NULL,
                             NUM_RELATION_STATS_ARGS,
                             InvalidOid, NULL, NULL);
 
    if (!stats_fill_fcinfo_from_arg_pairs(fcinfo, positional_fcinfo,
                                          relarginfo))
        result = false;
 
    if (!relation_statistics_update(positional_fcinfo))
        result = false;
 
    PG_RETURN_BOOL(result);
}