vacuum.c File Reference

#include "postgres.h"
#include <math.h>
#include "access/clog.h"
#include "access/commit_ts.h"
#include "access/genam.h"
#include "access/heapam.h"
#include "access/htup_details.h"
#include "access/multixact.h"
#include "access/transam.h"
#include "access/xact.h"
#include "catalog/namespace.h"
#include "catalog/pg_database.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_namespace.h"
#include "commands/cluster.h"
#include "commands/vacuum.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "pgstat.h"
#include "postmaster/autovacuum.h"
#include "storage/bufmgr.h"
#include "storage/lmgr.h"
#include "storage/proc.h"
#include "storage/procarray.h"
#include "utils/acl.h"
#include "utils/fmgroids.h"
#include "utils/guc.h"
#include "utils/memutils.h"
#include "utils/snapmgr.h"
#include "utils/syscache.h"
#include "utils/tqual.h"

Include dependency graph for vacuum.c:

Go to the source code of this file.

Functions
static List *	expand_vacuum_rel (VacuumRelation *vrel)
static List *	get_all_vacuum_rels (void)
static void	vac_truncate_clog (TransactionId frozenXID, MultiXactId minMulti, TransactionId lastSaneFrozenXid, MultiXactId lastSaneMinMulti)
static bool	vacuum_rel (Oid relid, RangeVar *relation, int options, VacuumParams *params)
void	ExecVacuum (VacuumStmt *vacstmt, bool isTopLevel)
void	vacuum (int options, List *relations, VacuumParams *params, BufferAccessStrategy bstrategy, bool isTopLevel)
void	vacuum_set_xid_limits (Relation rel, int freeze_min_age, int freeze_table_age, int multixact_freeze_min_age, int multixact_freeze_table_age, TransactionId *oldestXmin, TransactionId *freezeLimit, TransactionId *xidFullScanLimit, MultiXactId *multiXactCutoff, MultiXactId *mxactFullScanLimit)
double	vac_estimate_reltuples (Relation relation, BlockNumber total_pages, BlockNumber scanned_pages, double scanned_tuples)
void	vac_update_relstats (Relation relation, BlockNumber num_pages, double num_tuples, BlockNumber num_all_visible_pages, bool hasindex, TransactionId frozenxid, MultiXactId minmulti, bool in_outer_xact)
void	vac_update_datfrozenxid (void)
void	vac_open_indexes (Relation relation, LOCKMODE lockmode, int *nindexes, Relation **Irel)
void	vac_close_indexes (int nindexes, Relation *Irel, LOCKMODE lockmode)
void	vacuum_delay_point (void)

Variables
int	vacuum_freeze_min_age
int	vacuum_freeze_table_age
int	vacuum_multixact_freeze_min_age
int	vacuum_multixact_freeze_table_age
static MemoryContext	vac_context = NULL
static BufferAccessStrategy	vac_strategy

Function Documentation

ExecVacuum()

void ExecVacuum	(	VacuumStmt *	vacstmt,
		bool	isTopLevel
	)

Definition at line 87 of file vacuum.c.

References Assert, ereport, errcode(), errmsg(), ERROR, VacuumParams::freeze_min_age, VacuumParams::freeze_table_age, VacuumParams::is_wraparound, lfirst_node, VacuumParams::log_min_duration, VacuumParams::multixact_freeze_min_age, VacuumParams::multixact_freeze_table_age, NIL, VacuumStmt::options, VacuumStmt::rels, VacuumRelation::va_cols, VACOPT_ANALYZE, VACOPT_FREEZE, VACOPT_FULL, VACOPT_SKIPTOAST, VACOPT_VACUUM, and vacuum().

Referenced by standard_ProcessUtility().

{
    VacuumParams params;

    /* sanity checks on options */
    Assert(vacstmt->options & (VACOPT_VACUUM | VACOPT_ANALYZE));
    Assert((vacstmt->options & VACOPT_VACUUM) ||
           !(vacstmt->options & (VACOPT_FULL | VACOPT_FREEZE)));
    Assert(!(vacstmt->options & VACOPT_SKIPTOAST));

    /*
     * Make sure VACOPT_ANALYZE is specified if any column lists are present.
     */
    if (!(vacstmt->options & VACOPT_ANALYZE))
    {
        ListCell   *lc;

        foreach(lc, vacstmt->rels)
        {
            VacuumRelation *vrel = lfirst_node(VacuumRelation, lc);

            if (vrel->va_cols != NIL)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("ANALYZE option must be specified when a column list is provided")));
        }
    }

    /*
     * All freeze ages are zero if the FREEZE option is given; otherwise pass
     * them as -1 which means to use the default values.
     */
    if (vacstmt->options & VACOPT_FREEZE)
    {
        params.freeze_min_age = 0;
        params.freeze_table_age = 0;
        params.multixact_freeze_min_age = 0;
        params.multixact_freeze_table_age = 0;
    }
    else
    {
        params.freeze_min_age = -1;
        params.freeze_table_age = -1;
        params.multixact_freeze_min_age = -1;
        params.multixact_freeze_table_age = -1;
    }

    /* user-invoked vacuum is never "for wraparound" */
    params.is_wraparound = false;

    /* user-invoked vacuum never uses this parameter */
    params.log_min_duration = -1;

    /* Now go through the common routine */
    vacuum(vacstmt->options, vacstmt->rels, &params, NULL, isTopLevel);
}

expand_vacuum_rel()

static List * expand_vacuum_rel ( VacuumRelation *  vrel )

static

Definition at line 426 of file vacuum.c.

References AccessShareLock, elog, ERROR, find_all_inheritors(), GETSTRUCT, HeapTupleIsValid, lappend(), lfirst_oid, makeVacuumRelation(), MemoryContextSwitchTo(), NIL, NoLock, ObjectIdGetDatum, VacuumRelation::oid, OidIsValid, RangeVarGetRelid, VacuumRelation::relation, ReleaseSysCache(), RELOID, SearchSysCache1(), UnlockRelationOid(), and VacuumRelation::va_cols.

Referenced by vacuum().

{
    List       *vacrels = NIL;
    MemoryContext oldcontext;

    /* If caller supplied OID, there's nothing we need do here. */
    if (OidIsValid(vrel->oid))
    {
        oldcontext = MemoryContextSwitchTo(vac_context);
        vacrels = lappend(vacrels, vrel);
        MemoryContextSwitchTo(oldcontext);
    }
    else
    {
        /* Process a specific relation, and possibly partitions thereof */
        Oid         relid;
        HeapTuple   tuple;
        Form_pg_class classForm;
        bool        include_parts;

        /*
         * We transiently take AccessShareLock to protect the syscache lookup
         * below, as well as find_all_inheritors's expectation that the caller
         * holds some lock on the starting relation.
         */
        relid = RangeVarGetRelid(vrel->relation, AccessShareLock, false);

        /*
         * Make a returnable VacuumRelation for this rel.
         */
        oldcontext = MemoryContextSwitchTo(vac_context);
        vacrels = lappend(vacrels, makeVacuumRelation(vrel->relation,
                                                      relid,
                                                      vrel->va_cols));
        MemoryContextSwitchTo(oldcontext);

        /*
         * To check whether the relation is a partitioned table, fetch its
         * syscache entry.
         */
        tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
        if (!HeapTupleIsValid(tuple))
            elog(ERROR, "cache lookup failed for relation %u", relid);
        classForm = (Form_pg_class) GETSTRUCT(tuple);
        include_parts = (classForm->relkind == RELKIND_PARTITIONED_TABLE);
        ReleaseSysCache(tuple);

        /*
         * If it is, make relation list entries for its partitions.  Note that
         * the list returned by find_all_inheritors() includes the passed-in
         * OID, so we have to skip that.  There's no point in taking locks on
         * the individual partitions yet, and doing so would just add
         * unnecessary deadlock risk.
         */
        if (include_parts)
        {
            List       *part_oids = find_all_inheritors(relid, NoLock, NULL);
            ListCell   *part_lc;

            foreach(part_lc, part_oids)
            {
                Oid         part_oid = lfirst_oid(part_lc);

                if (part_oid == relid)
                    continue;   /* ignore original table */

                /*
                 * We omit a RangeVar since it wouldn't be appropriate to
                 * complain about failure to open one of these relations
                 * later.
                 */
                oldcontext = MemoryContextSwitchTo(vac_context);
                vacrels = lappend(vacrels, makeVacuumRelation(NULL,
                                                              part_oid,
                                                              vrel->va_cols));
                MemoryContextSwitchTo(oldcontext);
            }
        }

        /*
         * Release lock again.  This means that by the time we actually try to
         * process the table, it might be gone or renamed.  In the former case
         * we'll silently ignore it; in the latter case we'll process it
         * anyway, but we must beware that the RangeVar doesn't necessarily
         * identify it anymore.  This isn't ideal, perhaps, but there's little
         * practical alternative, since we're typically going to commit this
         * transaction and begin a new one between now and then.  Moreover,
         * holding locks on multiple relations would create significant risk
         * of deadlock.
         */
        UnlockRelationOid(relid, AccessShareLock);
    }

    return vacrels;
}

get_all_vacuum_rels()

static List * get_all_vacuum_rels ( void  )

static

Definition at line 527 of file vacuum.c.

References AccessShareLock, ForwardScanDirection, GETSTRUCT, heap_beginscan_catalog(), heap_close, heap_endscan(), heap_getnext(), heap_open(), HeapTupleGetOid, lappend(), makeVacuumRelation(), MemoryContextSwitchTo(), and NIL.

Referenced by vacuum().

{
    List       *vacrels = NIL;
    Relation    pgclass;
    HeapScanDesc scan;
    HeapTuple   tuple;

    pgclass = heap_open(RelationRelationId, AccessShareLock);

    scan = heap_beginscan_catalog(pgclass, 0, NULL);

    while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
    {
        Form_pg_class classForm = (Form_pg_class) GETSTRUCT(tuple);
        MemoryContext oldcontext;

        /*
         * We include partitioned tables here; depending on which operation is
         * to be performed, caller will decide whether to process or ignore
         * them.
         */
        if (classForm->relkind != RELKIND_RELATION &&
            classForm->relkind != RELKIND_MATVIEW &&
            classForm->relkind != RELKIND_PARTITIONED_TABLE)
            continue;

        /*
         * Build VacuumRelation(s) specifying the table OIDs to be processed.
         * We omit a RangeVar since it wouldn't be appropriate to complain
         * about failure to open one of these relations later.
         */
        oldcontext = MemoryContextSwitchTo(vac_context);
        vacrels = lappend(vacrels, makeVacuumRelation(NULL,
                                                      HeapTupleGetOid(tuple),
                                                      NIL));
        MemoryContextSwitchTo(oldcontext);
    }

    heap_endscan(scan);
    heap_close(pgclass, AccessShareLock);

    return vacrels;
}

vac_close_indexes()

void vac_close_indexes	(	int	nindexes,
		Relation *	Irel,
		LOCKMODE	lockmode
	)

Definition at line 1651 of file vacuum.c.

References index_close(), and pfree().

Referenced by do_analyze_rel(), and lazy_vacuum_rel().

{
    if (Irel == NULL)
        return;

    while (nindexes--)
    {
        Relation    ind = Irel[nindexes];

        index_close(ind, lockmode);
    }
    pfree(Irel);
}

vac_estimate_reltuples()

double vac_estimate_reltuples	(	Relation	relation,
		BlockNumber	total_pages,
		BlockNumber	scanned_pages,
		double	scanned_tuples
	)

Definition at line 779 of file vacuum.c.

References RelationData::rd_rel.

Referenced by lazy_scan_heap(), and statapprox_heap().

{
    BlockNumber old_rel_pages = relation->rd_rel->relpages;
    double      old_rel_tuples = relation->rd_rel->reltuples;
    double      old_density;
    double      unscanned_pages;
    double      total_tuples;

    /* If we did scan the whole table, just use the count as-is */
    if (scanned_pages >= total_pages)
        return scanned_tuples;

    /*
     * If scanned_pages is zero but total_pages isn't, keep the existing value
     * of reltuples.  (Note: callers should avoid updating the pg_class
     * statistics in this situation, since no new information has been
     * provided.)
     */
    if (scanned_pages == 0)
        return old_rel_tuples;

    /*
     * If old value of relpages is zero, old density is indeterminate; we
     * can't do much except scale up scanned_tuples to match total_pages.
     */
    if (old_rel_pages == 0)
        return floor((scanned_tuples / scanned_pages) * total_pages + 0.5);

    /*
     * Okay, we've covered the corner cases.  The normal calculation is to
     * convert the old measurement to a density (tuples per page), then
     * estimate the number of tuples in the unscanned pages using that figure,
     * and finally add on the number of tuples in the scanned pages.
     */
    old_density = old_rel_tuples / old_rel_pages;
    unscanned_pages = (double) total_pages - (double) scanned_pages;
    total_tuples = old_density * unscanned_pages + scanned_tuples;
    return floor(total_tuples + 0.5);
}

vac_open_indexes()

void vac_open_indexes	(	Relation	relation,
		LOCKMODE	lockmode,
		int *	nindexes,
		Relation **	Irel
	)

Definition at line 1608 of file vacuum.c.

References Assert, i, index_close(), index_open(), IndexIsReady, lfirst_oid, list_free(), list_length(), NoLock, palloc(), RelationData::rd_index, and RelationGetIndexList().

Referenced by do_analyze_rel(), and lazy_vacuum_rel().

{
    List       *indexoidlist;
    ListCell   *indexoidscan;
    int         i;

    Assert(lockmode != NoLock);

    indexoidlist = RelationGetIndexList(relation);

    /* allocate enough memory for all indexes */
    i = list_length(indexoidlist);

    if (i > 0)
        *Irel = (Relation *) palloc(i * sizeof(Relation));
    else
        *Irel = NULL;

    /* collect just the ready indexes */
    i = 0;
    foreach(indexoidscan, indexoidlist)
    {
        Oid         indexoid = lfirst_oid(indexoidscan);
        Relation    indrel;

        indrel = index_open(indexoid, lockmode);
        if (IndexIsReady(indrel->rd_index))
            (*Irel)[i++] = indrel;
        else
            index_close(indrel, lockmode);
    }

    *nindexes = i;

    list_free(indexoidlist);
}

vac_truncate_clog()

static void vac_truncate_clog ( TransactionId  frozenXID, MultiXactId  minMulti, TransactionId  lastSaneFrozenXid, MultiXactId  lastSaneMinMulti  )

static

Definition at line 1155 of file vacuum.c.

References AccessShareLock, AdvanceOldestCommitTsXid(), Assert, datfrozenxid, datminmxid, ereport, errdetail(), errmsg(), FormData_pg_database, ForwardScanDirection, GETSTRUCT, heap_beginscan_catalog(), heap_close, heap_endscan(), heap_getnext(), heap_open(), HeapTupleGetOid, MultiXactIdIsValid, MultiXactIdPrecedes(), MyDatabaseId, ReadNewTransactionId(), SetMultiXactIdLimit(), SetTransactionIdLimit(), TransactionIdIsNormal, TransactionIdPrecedes(), TruncateCLOG(), TruncateCommitTs(), TruncateMultiXact(), and WARNING.

Referenced by vac_update_datfrozenxid().

{
    TransactionId nextXID = ReadNewTransactionId();
    Relation    relation;
    HeapScanDesc scan;
    HeapTuple   tuple;
    Oid         oldestxid_datoid;
    Oid         minmulti_datoid;
    bool        bogus = false;
    bool        frozenAlreadyWrapped = false;

    /* init oldest datoids to sync with my frozenXID/minMulti values */
    oldestxid_datoid = MyDatabaseId;
    minmulti_datoid = MyDatabaseId;

    /*
     * Scan pg_database to compute the minimum datfrozenxid/datminmxid
     *
     * Since vac_update_datfrozenxid updates datfrozenxid/datminmxid in-place,
     * the values could change while we look at them.  Fetch each one just
     * once to ensure sane behavior of the comparison logic.  (Here, as in
     * many other places, we assume that fetching or updating an XID in shared
     * storage is atomic.)
     *
     * Note: we need not worry about a race condition with new entries being
     * inserted by CREATE DATABASE.  Any such entry will have a copy of some
     * existing DB's datfrozenxid, and that source DB cannot be ours because
     * of the interlock against copying a DB containing an active backend.
     * Hence the new entry will not reduce the minimum.  Also, if two VACUUMs
     * concurrently modify the datfrozenxid's of different databases, the
     * worst possible outcome is that pg_xact is not truncated as aggressively
     * as it could be.
     */
    relation = heap_open(DatabaseRelationId, AccessShareLock);

    scan = heap_beginscan_catalog(relation, 0, NULL);

    while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
    {
        volatile FormData_pg_database *dbform = (Form_pg_database) GETSTRUCT(tuple);
        TransactionId datfrozenxid = dbform->datfrozenxid;
        TransactionId datminmxid = dbform->datminmxid;

        Assert(TransactionIdIsNormal(datfrozenxid));
        Assert(MultiXactIdIsValid(datminmxid));

        /*
         * If things are working properly, no database should have a
         * datfrozenxid or datminmxid that is "in the future".  However, such
         * cases have been known to arise due to bugs in pg_upgrade.  If we
         * see any entries that are "in the future", chicken out and don't do
         * anything.  This ensures we won't truncate clog before those
         * databases have been scanned and cleaned up.  (We will issue the
         * "already wrapped" warning if appropriate, though.)
         */
        if (TransactionIdPrecedes(lastSaneFrozenXid, datfrozenxid) ||
            MultiXactIdPrecedes(lastSaneMinMulti, datminmxid))
            bogus = true;

        if (TransactionIdPrecedes(nextXID, datfrozenxid))
            frozenAlreadyWrapped = true;
        else if (TransactionIdPrecedes(datfrozenxid, frozenXID))
        {
            frozenXID = datfrozenxid;
            oldestxid_datoid = HeapTupleGetOid(tuple);
        }

        if (MultiXactIdPrecedes(datminmxid, minMulti))
        {
            minMulti = datminmxid;
            minmulti_datoid = HeapTupleGetOid(tuple);
        }
    }

    heap_endscan(scan);

    heap_close(relation, AccessShareLock);

    /*
     * Do not truncate CLOG if we seem to have suffered wraparound already;
     * the computed minimum XID might be bogus.  This case should now be
     * impossible due to the defenses in GetNewTransactionId, but we keep the
     * test anyway.
     */
    if (frozenAlreadyWrapped)
    {
        ereport(WARNING,
                (errmsg("some databases have not been vacuumed in over 2 billion transactions"),
                 errdetail("You might have already suffered transaction-wraparound data loss.")));
        return;
    }

    /* chicken out if data is bogus in any other way */
    if (bogus)
        return;

    /*
     * Advance the oldest value for commit timestamps before truncating, so
     * that if a user requests a timestamp for a transaction we're truncating
     * away right after this point, they get NULL instead of an ugly "file not
     * found" error from slru.c.  This doesn't matter for xact/multixact
     * because they are not subject to arbitrary lookups from users.
     */
    AdvanceOldestCommitTsXid(frozenXID);

    /*
     * Truncate CLOG, multixact and CommitTs to the oldest computed value.
     */
    TruncateCLOG(frozenXID, oldestxid_datoid);
    TruncateCommitTs(frozenXID);
    TruncateMultiXact(minMulti, minmulti_datoid);

    /*
     * Update the wrap limit for GetNewTransactionId and creation of new
     * MultiXactIds.  Note: these functions will also signal the postmaster
     * for an(other) autovac cycle if needed.   XXX should we avoid possibly
     * signalling twice?
     */
    SetTransactionIdLimit(frozenXID, oldestxid_datoid);
    SetMultiXactIdLimit(minMulti, minmulti_datoid, false);
}

vac_update_datfrozenxid()

void vac_update_datfrozenxid

(

void

)

Definition at line 991 of file vacuum.c.

References AccessShareLock, Assert, DATABASEOID, elog, ERROR, ForceTransactionIdLimitUpdate(), GetOldestMultiXactId(), GetOldestXmin(), GETSTRUCT, heap_close, heap_freetuple(), heap_inplace_update(), heap_open(), HeapTupleIsValid, InvalidOid, MultiXactIdIsValid, MultiXactIdPrecedes(), MyDatabaseId, ObjectIdGetDatum, PROCARRAY_FLAGS_VACUUM, ReadNewTransactionId(), ReadNextMultiXactId(), RowExclusiveLock, SearchSysCacheCopy1, systable_beginscan(), systable_endscan(), systable_getnext(), TransactionIdIsNormal, TransactionIdPrecedes(), and vac_truncate_clog().

Referenced by do_autovacuum(), and vacuum().

{
    HeapTuple   tuple;
    Form_pg_database dbform;
    Relation    relation;
    SysScanDesc scan;
    HeapTuple   classTup;
    TransactionId newFrozenXid;
    MultiXactId newMinMulti;
    TransactionId lastSaneFrozenXid;
    MultiXactId lastSaneMinMulti;
    bool        bogus = false;
    bool        dirty = false;

    /*
     * Initialize the "min" calculation with GetOldestXmin, which is a
     * reasonable approximation to the minimum relfrozenxid for not-yet-
     * committed pg_class entries for new tables; see AddNewRelationTuple().
     * So we cannot produce a wrong minimum by starting with this.
     */
    newFrozenXid = GetOldestXmin(NULL, PROCARRAY_FLAGS_VACUUM);

    /*
     * Similarly, initialize the MultiXact "min" with the value that would be
     * used on pg_class for new tables.  See AddNewRelationTuple().
     */
    newMinMulti = GetOldestMultiXactId();

    /*
     * Identify the latest relfrozenxid and relminmxid values that we could
     * validly see during the scan.  These are conservative values, but it's
     * not really worth trying to be more exact.
     */
    lastSaneFrozenXid = ReadNewTransactionId();
    lastSaneMinMulti = ReadNextMultiXactId();

    /*
     * We must seqscan pg_class to find the minimum Xid, because there is no
     * index that can help us here.
     */
    relation = heap_open(RelationRelationId, AccessShareLock);

    scan = systable_beginscan(relation, InvalidOid, false,
                              NULL, 0, NULL);

    while ((classTup = systable_getnext(scan)) != NULL)
    {
        Form_pg_class classForm = (Form_pg_class) GETSTRUCT(classTup);

        /*
         * Only consider relations able to hold unfrozen XIDs (anything else
         * should have InvalidTransactionId in relfrozenxid anyway.)
         */
        if (classForm->relkind != RELKIND_RELATION &&
            classForm->relkind != RELKIND_MATVIEW &&
            classForm->relkind != RELKIND_TOASTVALUE)
            continue;

        Assert(TransactionIdIsNormal(classForm->relfrozenxid));
        Assert(MultiXactIdIsValid(classForm->relminmxid));

        /*
         * If things are working properly, no relation should have a
         * relfrozenxid or relminmxid that is "in the future".  However, such
         * cases have been known to arise due to bugs in pg_upgrade.  If we
         * see any entries that are "in the future", chicken out and don't do
         * anything.  This ensures we won't truncate clog before those
         * relations have been scanned and cleaned up.
         */
        if (TransactionIdPrecedes(lastSaneFrozenXid, classForm->relfrozenxid) ||
            MultiXactIdPrecedes(lastSaneMinMulti, classForm->relminmxid))
        {
            bogus = true;
            break;
        }

        if (TransactionIdPrecedes(classForm->relfrozenxid, newFrozenXid))
            newFrozenXid = classForm->relfrozenxid;

        if (MultiXactIdPrecedes(classForm->relminmxid, newMinMulti))
            newMinMulti = classForm->relminmxid;
    }

    /* we're done with pg_class */
    systable_endscan(scan);
    heap_close(relation, AccessShareLock);

    /* chicken out if bogus data found */
    if (bogus)
        return;

    Assert(TransactionIdIsNormal(newFrozenXid));
    Assert(MultiXactIdIsValid(newMinMulti));

    /* Now fetch the pg_database tuple we need to update. */
    relation = heap_open(DatabaseRelationId, RowExclusiveLock);

    /* Fetch a copy of the tuple to scribble on */
    tuple = SearchSysCacheCopy1(DATABASEOID, ObjectIdGetDatum(MyDatabaseId));
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "could not find tuple for database %u", MyDatabaseId);
    dbform = (Form_pg_database) GETSTRUCT(tuple);

    /*
     * As in vac_update_relstats(), we ordinarily don't want to let
     * datfrozenxid go backward; but if it's "in the future" then it must be
     * corrupt and it seems best to overwrite it.
     */
    if (dbform->datfrozenxid != newFrozenXid &&
        (TransactionIdPrecedes(dbform->datfrozenxid, newFrozenXid) ||
         TransactionIdPrecedes(lastSaneFrozenXid, dbform->datfrozenxid)))
    {
        dbform->datfrozenxid = newFrozenXid;
        dirty = true;
    }
    else
        newFrozenXid = dbform->datfrozenxid;

    /* Ditto for datminmxid */
    if (dbform->datminmxid != newMinMulti &&
        (MultiXactIdPrecedes(dbform->datminmxid, newMinMulti) ||
         MultiXactIdPrecedes(lastSaneMinMulti, dbform->datminmxid)))
    {
        dbform->datminmxid = newMinMulti;
        dirty = true;
    }
    else
        newMinMulti = dbform->datminmxid;

    if (dirty)
        heap_inplace_update(relation, tuple);

    heap_freetuple(tuple);
    heap_close(relation, RowExclusiveLock);

    /*
     * If we were able to advance datfrozenxid or datminmxid, see if we can
     * truncate pg_xact and/or pg_multixact.  Also do it if the shared
     * XID-wrap-limit info is stale, since this action will update that too.
     */
    if (dirty || ForceTransactionIdLimitUpdate())
        vac_truncate_clog(newFrozenXid, newMinMulti,
                          lastSaneFrozenXid, lastSaneMinMulti);
}

vac_update_relstats()

void vac_update_relstats	(	Relation	relation,
		BlockNumber	num_pages,
		double	num_tuples,
		BlockNumber	num_all_visible_pages,
		bool	hasindex,
		TransactionId	frozenxid,
		MultiXactId	minmulti,
		bool	in_outer_xact
	)

Definition at line 864 of file vacuum.c.

References elog, ERROR, GETSTRUCT, heap_close, heap_inplace_update(), heap_open(), HeapTupleIsValid, MultiXactIdIsValid, MultiXactIdPrecedes(), ObjectIdGetDatum, RelationData::rd_rules, ReadNewTransactionId(), ReadNextMultiXactId(), RelationGetRelid, RELOID, RowExclusiveLock, SearchSysCacheCopy1, TransactionIdIsNormal, TransactionIdPrecedes(), and RelationData::trigdesc.

Referenced by do_analyze_rel(), lazy_cleanup_index(), and lazy_vacuum_rel().

{
    Oid         relid = RelationGetRelid(relation);
    Relation    rd;
    HeapTuple   ctup;
    Form_pg_class pgcform;
    bool        dirty;

    rd = heap_open(RelationRelationId, RowExclusiveLock);

    /* Fetch a copy of the tuple to scribble on */
    ctup = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
    if (!HeapTupleIsValid(ctup))
        elog(ERROR, "pg_class entry for relid %u vanished during vacuuming",
             relid);
    pgcform = (Form_pg_class) GETSTRUCT(ctup);

    /* Apply statistical updates, if any, to copied tuple */

    dirty = false;
    if (pgcform->relpages != (int32) num_pages)
    {
        pgcform->relpages = (int32) num_pages;
        dirty = true;
    }
    if (pgcform->reltuples != (float4) num_tuples)
    {
        pgcform->reltuples = (float4) num_tuples;
        dirty = true;
    }
    if (pgcform->relallvisible != (int32) num_all_visible_pages)
    {
        pgcform->relallvisible = (int32) num_all_visible_pages;
        dirty = true;
    }

    /* Apply DDL updates, but not inside an outer transaction (see above) */

    if (!in_outer_xact)
    {
        /*
         * If we didn't find any indexes, reset relhasindex.
         */
        if (pgcform->relhasindex && !hasindex)
        {
            pgcform->relhasindex = false;
            dirty = true;
        }

        /* We also clear relhasrules and relhastriggers if needed */
        if (pgcform->relhasrules && relation->rd_rules == NULL)
        {
            pgcform->relhasrules = false;
            dirty = true;
        }
        if (pgcform->relhastriggers && relation->trigdesc == NULL)
        {
            pgcform->relhastriggers = false;
            dirty = true;
        }
    }

    /*
     * Update relfrozenxid, unless caller passed InvalidTransactionId
     * indicating it has no new data.
     *
     * Ordinarily, we don't let relfrozenxid go backwards: if things are
     * working correctly, the only way the new frozenxid could be older would
     * be if a previous VACUUM was done with a tighter freeze_min_age, in
     * which case we don't want to forget the work it already did.  However,
     * if the stored relfrozenxid is "in the future", then it must be corrupt
     * and it seems best to overwrite it with the cutoff we used this time.
     * This should match vac_update_datfrozenxid() concerning what we consider
     * to be "in the future".
     */
    if (TransactionIdIsNormal(frozenxid) &&
        pgcform->relfrozenxid != frozenxid &&
        (TransactionIdPrecedes(pgcform->relfrozenxid, frozenxid) ||
         TransactionIdPrecedes(ReadNewTransactionId(),
                               pgcform->relfrozenxid)))
    {
        pgcform->relfrozenxid = frozenxid;
        dirty = true;
    }

    /* Similarly for relminmxid */
    if (MultiXactIdIsValid(minmulti) &&
        pgcform->relminmxid != minmulti &&
        (MultiXactIdPrecedes(pgcform->relminmxid, minmulti) ||
         MultiXactIdPrecedes(ReadNextMultiXactId(), pgcform->relminmxid)))
    {
        pgcform->relminmxid = minmulti;
        dirty = true;
    }

    /* If anything changed, write out the tuple. */
    if (dirty)
        heap_inplace_update(rd, ctup);

    heap_close(rd, RowExclusiveLock);
}

vacuum()

void vacuum	(	int	options,
		List *	relations,
		VacuumParams *	params,
		BufferAccessStrategy	bstrategy,
		bool	isTopLevel
	)

Definition at line 166 of file vacuum.c.

References ActiveSnapshotSet(), ALLOCSET_DEFAULT_SIZES, AllocSetContextCreate, analyze_rel(), Assert, BAS_VACUUM, CommitTransactionCommand(), cur, ereport, errcode(), errmsg(), ERROR, expand_vacuum_rel(), get_all_vacuum_rels(), GetAccessStrategy(), GetTransactionSnapshot(), IsAutoVacuumWorkerProcess(), IsInTransactionBlock(), lfirst_node, list_concat(), list_length(), MemoryContextDelete(), MemoryContextSwitchTo(), NIL, VacuumRelation::oid, PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, pgstat_vacuum_stat(), PopActiveSnapshot(), PortalContext, PreventInTransactionBlock(), PushActiveSnapshot(), VacuumRelation::relation, StartTransactionCommand(), VacuumRelation::va_cols, vac_update_datfrozenxid(), VACOPT_ANALYZE, VACOPT_DISABLE_PAGE_SKIPPING, VACOPT_FULL, VACOPT_VACUUM, vacuum_rel(), VacuumCostActive, VacuumCostBalance, VacuumCostDelay, VacuumPageDirty, VacuumPageHit, and VacuumPageMiss.

Referenced by autovacuum_do_vac_analyze(), and ExecVacuum().

{
    static bool in_vacuum = false;

    const char *stmttype;
    volatile bool in_outer_xact,
                use_own_xacts;

    Assert(params != NULL);

    stmttype = (options & VACOPT_VACUUM) ? "VACUUM" : "ANALYZE";

    /*
     * We cannot run VACUUM inside a user transaction block; if we were inside
     * a transaction, then our commit- and start-transaction-command calls
     * would not have the intended effect!  There are numerous other subtle
     * dependencies on this, too.
     *
     * ANALYZE (without VACUUM) can run either way.
     */
    if (options & VACOPT_VACUUM)
    {
        PreventInTransactionBlock(isTopLevel, stmttype);
        in_outer_xact = false;
    }
    else
        in_outer_xact = IsInTransactionBlock(isTopLevel);

    /*
     * Due to static variables vac_context, anl_context and vac_strategy,
     * vacuum() is not reentrant.  This matters when VACUUM FULL or ANALYZE
     * calls a hostile index expression that itself calls ANALYZE.
     */
    if (in_vacuum)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("%s cannot be executed from VACUUM or ANALYZE",
                        stmttype)));

    /*
     * Sanity check DISABLE_PAGE_SKIPPING option.
     */
    if ((options & VACOPT_FULL) != 0 &&
        (options & VACOPT_DISABLE_PAGE_SKIPPING) != 0)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("VACUUM option DISABLE_PAGE_SKIPPING cannot be used with FULL")));

    /*
     * Send info about dead objects to the statistics collector, unless we are
     * in autovacuum --- autovacuum.c does this for itself.
     */
    if ((options & VACOPT_VACUUM) && !IsAutoVacuumWorkerProcess())
        pgstat_vacuum_stat();

    /*
     * Create special memory context for cross-transaction storage.
     *
     * Since it is a child of PortalContext, it will go away eventually even
     * if we suffer an error; there's no need for special abort cleanup logic.
     */
    vac_context = AllocSetContextCreate(PortalContext,
                                        "Vacuum",
                                        ALLOCSET_DEFAULT_SIZES);

    /*
     * If caller didn't give us a buffer strategy object, make one in the
     * cross-transaction memory context.
     */
    if (bstrategy == NULL)
    {
        MemoryContext old_context = MemoryContextSwitchTo(vac_context);

        bstrategy = GetAccessStrategy(BAS_VACUUM);
        MemoryContextSwitchTo(old_context);
    }
    vac_strategy = bstrategy;

    /*
     * Build list of relation(s) to process, putting any new data in
     * vac_context for safekeeping.
     */
    if (relations != NIL)
    {
        List       *newrels = NIL;
        ListCell   *lc;

        foreach(lc, relations)
        {
            VacuumRelation *vrel = lfirst_node(VacuumRelation, lc);
            List       *sublist;
            MemoryContext old_context;

            sublist = expand_vacuum_rel(vrel);
            old_context = MemoryContextSwitchTo(vac_context);
            newrels = list_concat(newrels, sublist);
            MemoryContextSwitchTo(old_context);
        }
        relations = newrels;
    }
    else
        relations = get_all_vacuum_rels();

    /*
     * Decide whether we need to start/commit our own transactions.
     *
     * For VACUUM (with or without ANALYZE): always do so, so that we can
     * release locks as soon as possible.  (We could possibly use the outer
     * transaction for a one-table VACUUM, but handling TOAST tables would be
     * problematic.)
     *
     * For ANALYZE (no VACUUM): if inside a transaction block, we cannot
     * start/commit our own transactions.  Also, there's no need to do so if
     * only processing one relation.  For multiple relations when not within a
     * transaction block, and also in an autovacuum worker, use own
     * transactions so we can release locks sooner.
     */
    if (options & VACOPT_VACUUM)
        use_own_xacts = true;
    else
    {
        Assert(options & VACOPT_ANALYZE);
        if (IsAutoVacuumWorkerProcess())
            use_own_xacts = true;
        else if (in_outer_xact)
            use_own_xacts = false;
        else if (list_length(relations) > 1)
            use_own_xacts = true;
        else
            use_own_xacts = false;
    }

    /*
     * vacuum_rel expects to be entered with no transaction active; it will
     * start and commit its own transaction.  But we are called by an SQL
     * command, and so we are executing inside a transaction already. We
     * commit the transaction started in PostgresMain() here, and start
     * another one before exiting to match the commit waiting for us back in
     * PostgresMain().
     */
    if (use_own_xacts)
    {
        Assert(!in_outer_xact);

        /* ActiveSnapshot is not set by autovacuum */
        if (ActiveSnapshotSet())
            PopActiveSnapshot();

        /* matches the StartTransaction in PostgresMain() */
        CommitTransactionCommand();
    }

    /* Turn vacuum cost accounting on or off, and set/clear in_vacuum */
    PG_TRY();
    {
        ListCell   *cur;

        in_vacuum = true;
        VacuumCostActive = (VacuumCostDelay > 0);
        VacuumCostBalance = 0;
        VacuumPageHit = 0;
        VacuumPageMiss = 0;
        VacuumPageDirty = 0;

        /*
         * Loop to process each selected relation.
         */
        foreach(cur, relations)
        {
            VacuumRelation *vrel = lfirst_node(VacuumRelation, cur);

            if (options & VACOPT_VACUUM)
            {
                if (!vacuum_rel(vrel->oid, vrel->relation, options, params))
                    continue;
            }

            if (options & VACOPT_ANALYZE)
            {
                /*
                 * If using separate xacts, start one for analyze. Otherwise,
                 * we can use the outer transaction.
                 */
                if (use_own_xacts)
                {
                    StartTransactionCommand();
                    /* functions in indexes may want a snapshot set */
                    PushActiveSnapshot(GetTransactionSnapshot());
                }

                analyze_rel(vrel->oid, vrel->relation, options, params,
                            vrel->va_cols, in_outer_xact, vac_strategy);

                if (use_own_xacts)
                {
                    PopActiveSnapshot();
                    CommitTransactionCommand();
                }
            }
        }
    }
    PG_CATCH();
    {
        in_vacuum = false;
        VacuumCostActive = false;
        PG_RE_THROW();
    }
    PG_END_TRY();

    in_vacuum = false;
    VacuumCostActive = false;

    /*
     * Finish up processing.
     */
    if (use_own_xacts)
    {
        /* here, we are not in a transaction */

        /*
         * This matches the CommitTransaction waiting for us in
         * PostgresMain().
         */
        StartTransactionCommand();
    }

    if ((options & VACOPT_VACUUM) && !IsAutoVacuumWorkerProcess())
    {
        /*
         * Update pg_database.datfrozenxid, and truncate pg_xact if possible.
         * (autovacuum.c does this for itself.)
         */
        vac_update_datfrozenxid();
    }

    /*
     * Clean up working storage --- note we must do this after
     * StartTransactionCommand, else we might be trying to delete the active
     * context!
     */
    MemoryContextDelete(vac_context);
    vac_context = NULL;
}

vacuum_delay_point()

void vacuum_delay_point

(

void

)

Definition at line 1672 of file vacuum.c.

References AutoVacuumUpdateDelay(), CHECK_FOR_INTERRUPTS, InterruptPending, pg_usleep(), VacuumCostActive, VacuumCostBalance, VacuumCostDelay, and VacuumCostLimit.

Referenced by acquire_sample_rows(), blbulkdelete(), blvacuumcleanup(), btvacuumpage(), compute_array_stats(), compute_distinct_stats(), compute_index_stats(), compute_range_stats(), compute_scalar_stats(), compute_trivial_stats(), compute_tsvector_stats(), file_acquire_sample_rows(), ginbulkdelete(), ginInsertCleanup(), ginvacuumcleanup(), ginVacuumPostingTreeLeaves(), gistbulkdelete(), gistvacuumcleanup(), hashbucketcleanup(), lazy_scan_heap(), lazy_vacuum_heap(), spgprocesspending(), and spgvacuumpage().

{
    /* Always check for interrupts */
    CHECK_FOR_INTERRUPTS();

    /* Nap if appropriate */
    if (VacuumCostActive && !InterruptPending &&
        VacuumCostBalance >= VacuumCostLimit)
    {
        int         msec;

        msec = VacuumCostDelay * VacuumCostBalance / VacuumCostLimit;
        if (msec > VacuumCostDelay * 4)
            msec = VacuumCostDelay * 4;

        pg_usleep(msec * 1000L);

        VacuumCostBalance = 0;

        /* update balance values for workers */
        AutoVacuumUpdateDelay();

        /* Might have gotten an interrupt while sleeping */
        CHECK_FOR_INTERRUPTS();
    }
}

vacuum_rel()

static bool vacuum_rel ( Oid  relid, RangeVar *  relation, int  options, VacuumParams *  params  )

static

Definition at line 1301 of file vacuum.c.

References AccessExclusiveLock, Assert, AtEOXact_GUC(), CHECK_FOR_INTERRUPTS, cluster_rel(), CommitTransactionCommand(), ConditionalLockRelationOid(), elevel, ereport, errcode(), ERRCODE_UNDEFINED_TABLE, errmsg(), GetTransactionSnapshot(), GetUserId(), GetUserIdAndSecContext(), InvalidOid, VacuumParams::is_wraparound, IsAutoVacuumWorkerProcess(), lazy_vacuum_rel(), LockRelationIdForSession(), LockInfoData::lockRelId, LOG, VacuumParams::log_min_duration, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), MyDatabaseId, MyPgXact, NewGUCNestLevel(), NoLock, pg_class_ownercheck(), pg_database_ownercheck(), PopActiveSnapshot(), PROC_IN_VACUUM, PROC_VACUUM_FOR_WRAPAROUND, PushActiveSnapshot(), RelationData::rd_lockInfo, RelationData::rd_rel, relation_close(), RELATION_IS_OTHER_TEMP, RelationGetRelationName, RelationGetRelid, RangeVar::relname, SECURITY_RESTRICTED_OPERATION, SetUserIdAndSecContext(), ShareUpdateExclusiveLock, StartTransactionCommand(), try_relation_open(), UnlockRelationIdForSession(), VACOPT_FULL, VACOPT_NOWAIT, VACOPT_SKIPTOAST, VACOPT_VERBOSE, PGXACT::vacuumFlags, and WARNING.

Referenced by vacuum().

{
    LOCKMODE    lmode;
    Relation    onerel;
    LockRelId   onerelid;
    Oid         toast_relid;
    Oid         save_userid;
    int         save_sec_context;
    int         save_nestlevel;
    bool        rel_lock = true;

    Assert(params != NULL);

    /* Begin a transaction for vacuuming this relation */
    StartTransactionCommand();

    /*
     * Functions in indexes may want a snapshot set.  Also, setting a snapshot
     * ensures that RecentGlobalXmin is kept truly recent.
     */
    PushActiveSnapshot(GetTransactionSnapshot());

    if (!(options & VACOPT_FULL))
    {
        /*
         * In lazy vacuum, we can set the PROC_IN_VACUUM flag, which lets
         * other concurrent VACUUMs know that they can ignore this one while
         * determining their OldestXmin.  (The reason we don't set it during a
         * full VACUUM is exactly that we may have to run user-defined
         * functions for functional indexes, and we want to make sure that if
         * they use the snapshot set above, any tuples it requires can't get
         * removed from other tables.  An index function that depends on the
         * contents of other tables is arguably broken, but we won't break it
         * here by violating transaction semantics.)
         *
         * We also set the VACUUM_FOR_WRAPAROUND flag, which is passed down by
         * autovacuum; it's used to avoid canceling a vacuum that was invoked
         * in an emergency.
         *
         * Note: these flags remain set until CommitTransaction or
         * AbortTransaction.  We don't want to clear them until we reset
         * MyPgXact->xid/xmin, else OldestXmin might appear to go backwards,
         * which is probably Not Good.
         */
        LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
        MyPgXact->vacuumFlags |= PROC_IN_VACUUM;
        if (params->is_wraparound)
            MyPgXact->vacuumFlags |= PROC_VACUUM_FOR_WRAPAROUND;
        LWLockRelease(ProcArrayLock);
    }

    /*
     * Check for user-requested abort.  Note we want this to be inside a
     * transaction, so xact.c doesn't issue useless WARNING.
     */
    CHECK_FOR_INTERRUPTS();

    /*
     * Determine the type of lock we want --- hard exclusive lock for a FULL
     * vacuum, but just ShareUpdateExclusiveLock for concurrent vacuum. Either
     * way, we can be sure that no other backend is vacuuming the same table.
     */
    lmode = (options & VACOPT_FULL) ? AccessExclusiveLock : ShareUpdateExclusiveLock;

    /*
     * Open the relation and get the appropriate lock on it.
     *
     * There's a race condition here: the rel may have gone away since the
     * last time we saw it.  If so, we don't need to vacuum it.
     *
     * If we've been asked not to wait for the relation lock, acquire it first
     * in non-blocking mode, before calling try_relation_open().
     */
    if (!(options & VACOPT_NOWAIT))
        onerel = try_relation_open(relid, lmode);
    else if (ConditionalLockRelationOid(relid, lmode))
        onerel = try_relation_open(relid, NoLock);
    else
    {
        onerel = NULL;
        rel_lock = false;
    }

    /*
     * If we failed to open or lock the relation, emit a log message before
     * exiting.
     */
    if (!onerel)
    {
        int         elevel = 0;

        /*
         * Determine the log level.
         *
         * If the RangeVar is not defined, we do not have enough information
         * to provide a meaningful log statement.  Chances are that
         * vacuum_rel's caller has intentionally not provided this information
         * so that this logging is skipped, anyway.
         *
         * Otherwise, for autovacuum logs, we emit a LOG if
         * log_autovacuum_min_duration is not disabled.  For manual VACUUM, we
         * emit a WARNING to match the log statements in the permission
         * checks.
         */
        if (relation != NULL)
        {
            if (!IsAutoVacuumWorkerProcess())
                elevel = WARNING;
            else if (params->log_min_duration >= 0)
                elevel = LOG;
        }

        if (elevel != 0)
        {
            if (!rel_lock)
                ereport(elevel,
                        (errcode(ERRCODE_LOCK_NOT_AVAILABLE),
                         errmsg("skipping vacuum of \"%s\" --- lock not available",
                                relation->relname)));
            else
                ereport(elevel,
                        (errcode(ERRCODE_UNDEFINED_TABLE),
                         errmsg("skipping vacuum of \"%s\" --- relation no longer exists",
                                relation->relname)));
        }

        PopActiveSnapshot();
        CommitTransactionCommand();
        return false;
    }

    /*
     * Check permissions.
     *
     * We allow the user to vacuum a table if he is superuser, the table
     * owner, or the database owner (but in the latter case, only if it's not
     * a shared relation).  pg_class_ownercheck includes the superuser case.
     *
     * Note we choose to treat permissions failure as a WARNING and keep
     * trying to vacuum the rest of the DB --- is this appropriate?
     */
    if (!(pg_class_ownercheck(RelationGetRelid(onerel), GetUserId()) ||
          (pg_database_ownercheck(MyDatabaseId, GetUserId()) && !onerel->rd_rel->relisshared)))
    {
        if (onerel->rd_rel->relisshared)
            ereport(WARNING,
                    (errmsg("skipping \"%s\" --- only superuser can vacuum it",
                            RelationGetRelationName(onerel))));
        else if (onerel->rd_rel->relnamespace == PG_CATALOG_NAMESPACE)
            ereport(WARNING,
                    (errmsg("skipping \"%s\" --- only superuser or database owner can vacuum it",
                            RelationGetRelationName(onerel))));
        else
            ereport(WARNING,
                    (errmsg("skipping \"%s\" --- only table or database owner can vacuum it",
                            RelationGetRelationName(onerel))));
        relation_close(onerel, lmode);
        PopActiveSnapshot();
        CommitTransactionCommand();
        return false;
    }

    /*
     * Check that it's of a vacuumable relkind.
     */
    if (onerel->rd_rel->relkind != RELKIND_RELATION &&
        onerel->rd_rel->relkind != RELKIND_MATVIEW &&
        onerel->rd_rel->relkind != RELKIND_TOASTVALUE &&
        onerel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
    {
        ereport(WARNING,
                (errmsg("skipping \"%s\" --- cannot vacuum non-tables or special system tables",
                        RelationGetRelationName(onerel))));
        relation_close(onerel, lmode);
        PopActiveSnapshot();
        CommitTransactionCommand();
        return false;
    }

    /*
     * Silently ignore tables that are temp tables of other backends ---
     * trying to vacuum these will lead to great unhappiness, since their
     * contents are probably not up-to-date on disk.  (We don't throw a
     * warning here; it would just lead to chatter during a database-wide
     * VACUUM.)
     */
    if (RELATION_IS_OTHER_TEMP(onerel))
    {
        relation_close(onerel, lmode);
        PopActiveSnapshot();
        CommitTransactionCommand();
        return false;
    }

    /*
     * Silently ignore partitioned tables as there is no work to be done.  The
     * useful work is on their child partitions, which have been queued up for
     * us separately.
     */
    if (onerel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    {
        relation_close(onerel, lmode);
        PopActiveSnapshot();
        CommitTransactionCommand();
        /* It's OK to proceed with ANALYZE on this table */
        return true;
    }

    /*
     * Get a session-level lock too. This will protect our access to the
     * relation across multiple transactions, so that we can vacuum the
     * relation's TOAST table (if any) secure in the knowledge that no one is
     * deleting the parent relation.
     *
     * NOTE: this cannot block, even if someone else is waiting for access,
     * because the lock manager knows that both lock requests are from the
     * same process.
     */
    onerelid = onerel->rd_lockInfo.lockRelId;
    LockRelationIdForSession(&onerelid, lmode);

    /*
     * Remember the relation's TOAST relation for later, if the caller asked
     * us to process it.  In VACUUM FULL, though, the toast table is
     * automatically rebuilt by cluster_rel so we shouldn't recurse to it.
     */
    if (!(options & VACOPT_SKIPTOAST) && !(options & VACOPT_FULL))
        toast_relid = onerel->rd_rel->reltoastrelid;
    else
        toast_relid = InvalidOid;

    /*
     * Switch to the table owner's userid, so that any index functions are run
     * as that user.  Also lock down security-restricted operations and
     * arrange to make GUC variable changes local to this command. (This is
     * unnecessary, but harmless, for lazy VACUUM.)
     */
    GetUserIdAndSecContext(&save_userid, &save_sec_context);
    SetUserIdAndSecContext(onerel->rd_rel->relowner,
                           save_sec_context | SECURITY_RESTRICTED_OPERATION);
    save_nestlevel = NewGUCNestLevel();

    /*
     * Do the actual work --- either FULL or "lazy" vacuum
     */
    if (options & VACOPT_FULL)
    {
        /* close relation before vacuuming, but hold lock until commit */
        relation_close(onerel, NoLock);
        onerel = NULL;

        /* VACUUM FULL is now a variant of CLUSTER; see cluster.c */
        cluster_rel(relid, InvalidOid, false,
                    (options & VACOPT_VERBOSE) != 0);
    }
    else
        lazy_vacuum_rel(onerel, options, params, vac_strategy);

    /* Roll back any GUC changes executed by index functions */
    AtEOXact_GUC(false, save_nestlevel);

    /* Restore userid and security context */
    SetUserIdAndSecContext(save_userid, save_sec_context);

    /* all done with this class, but hold lock until commit */
    if (onerel)
        relation_close(onerel, NoLock);

    /*
     * Complete the transaction and free all temporary memory used.
     */
    PopActiveSnapshot();
    CommitTransactionCommand();

    /*
     * If the relation has a secondary toast rel, vacuum that too while we
     * still hold the session lock on the master table.  Note however that
     * "analyze" will not get done on the toast table.  This is good, because
     * the toaster always uses hardcoded index access and statistics are
     * totally unimportant for toast relations.
     */
    if (toast_relid != InvalidOid)
        vacuum_rel(toast_relid, NULL, options, params);

    /*
     * Now release the session-level lock on the master table.
     */
    UnlockRelationIdForSession(&onerelid, lmode);

    /* Report that we really did it. */
    return true;
}

vacuum_set_xid_limits()

void vacuum_set_xid_limits	(	Relation	rel,
		int	freeze_min_age,
		int	freeze_table_age,
		int	multixact_freeze_min_age,
		int	multixact_freeze_table_age,
		TransactionId *	oldestXmin,
		TransactionId *	freezeLimit,
		TransactionId *	xidFullScanLimit,
		MultiXactId *	multiXactCutoff,
		MultiXactId *	mxactFullScanLimit
	)

Definition at line 593 of file vacuum.c.

References Assert, autovacuum_freeze_max_age, ereport, errhint(), errmsg(), FirstMultiXactId, FirstNormalTransactionId, GetOldestMultiXactId(), GetOldestXmin(), Min, MultiXactIdPrecedes(), MultiXactMemberFreezeThreshold(), PROCARRAY_FLAGS_VACUUM, ReadNewTransactionId(), ReadNextMultiXactId(), TransactionIdIsNormal, TransactionIdLimitedForOldSnapshots(), TransactionIdPrecedes(), vacuum_freeze_min_age, vacuum_freeze_table_age, vacuum_multixact_freeze_min_age, vacuum_multixact_freeze_table_age, and WARNING.

Referenced by copy_heap_data(), and lazy_vacuum_rel().

{
    int         freezemin;
    int         mxid_freezemin;
    int         effective_multixact_freeze_max_age;
    TransactionId limit;
    TransactionId safeLimit;
    MultiXactId mxactLimit;
    MultiXactId safeMxactLimit;

    /*
     * We can always ignore processes running lazy vacuum.  This is because we
     * use these values only for deciding which tuples we must keep in the
     * tables.  Since lazy vacuum doesn't write its XID anywhere, it's safe to
     * ignore it.  In theory it could be problematic to ignore lazy vacuums in
     * a full vacuum, but keep in mind that only one vacuum process can be
     * working on a particular table at any time, and that each vacuum is
     * always an independent transaction.
     */
    *oldestXmin =
        TransactionIdLimitedForOldSnapshots(GetOldestXmin(rel, PROCARRAY_FLAGS_VACUUM), rel);

    Assert(TransactionIdIsNormal(*oldestXmin));

    /*
     * Determine the minimum freeze age to use: as specified by the caller, or
     * vacuum_freeze_min_age, but in any case not more than half
     * autovacuum_freeze_max_age, so that autovacuums to prevent XID
     * wraparound won't occur too frequently.
     */
    freezemin = freeze_min_age;
    if (freezemin < 0)
        freezemin = vacuum_freeze_min_age;
    freezemin = Min(freezemin, autovacuum_freeze_max_age / 2);
    Assert(freezemin >= 0);

    /*
     * Compute the cutoff XID, being careful not to generate a "permanent" XID
     */
    limit = *oldestXmin - freezemin;
    if (!TransactionIdIsNormal(limit))
        limit = FirstNormalTransactionId;

    /*
     * If oldestXmin is very far back (in practice, more than
     * autovacuum_freeze_max_age / 2 XIDs old), complain and force a minimum
     * freeze age of zero.
     */
    safeLimit = ReadNewTransactionId() - autovacuum_freeze_max_age;
    if (!TransactionIdIsNormal(safeLimit))
        safeLimit = FirstNormalTransactionId;

    if (TransactionIdPrecedes(limit, safeLimit))
    {
        ereport(WARNING,
                (errmsg("oldest xmin is far in the past"),
                 errhint("Close open transactions soon to avoid wraparound problems.\n"
                         "You might also need to commit or roll back old prepared transactions, or drop stale replication slots.")));
        limit = *oldestXmin;
    }

    *freezeLimit = limit;

    /*
     * Compute the multixact age for which freezing is urgent.  This is
     * normally autovacuum_multixact_freeze_max_age, but may be less if we are
     * short of multixact member space.
     */
    effective_multixact_freeze_max_age = MultiXactMemberFreezeThreshold();

    /*
     * Determine the minimum multixact freeze age to use: as specified by
     * caller, or vacuum_multixact_freeze_min_age, but in any case not more
     * than half effective_multixact_freeze_max_age, so that autovacuums to
     * prevent MultiXact wraparound won't occur too frequently.
     */
    mxid_freezemin = multixact_freeze_min_age;
    if (mxid_freezemin < 0)
        mxid_freezemin = vacuum_multixact_freeze_min_age;
    mxid_freezemin = Min(mxid_freezemin,
                         effective_multixact_freeze_max_age / 2);
    Assert(mxid_freezemin >= 0);

    /* compute the cutoff multi, being careful to generate a valid value */
    mxactLimit = GetOldestMultiXactId() - mxid_freezemin;
    if (mxactLimit < FirstMultiXactId)
        mxactLimit = FirstMultiXactId;

    safeMxactLimit =
        ReadNextMultiXactId() - effective_multixact_freeze_max_age;
    if (safeMxactLimit < FirstMultiXactId)
        safeMxactLimit = FirstMultiXactId;

    if (MultiXactIdPrecedes(mxactLimit, safeMxactLimit))
    {
        ereport(WARNING,
                (errmsg("oldest multixact is far in the past"),
                 errhint("Close open transactions with multixacts soon to avoid wraparound problems.")));
        mxactLimit = safeMxactLimit;
    }

    *multiXactCutoff = mxactLimit;

    if (xidFullScanLimit != NULL)
    {
        int         freezetable;

        Assert(mxactFullScanLimit != NULL);

        /*
         * Determine the table freeze age to use: as specified by the caller,
         * or vacuum_freeze_table_age, but in any case not more than
         * autovacuum_freeze_max_age * 0.95, so that if you have e.g nightly
         * VACUUM schedule, the nightly VACUUM gets a chance to freeze tuples
         * before anti-wraparound autovacuum is launched.
         */
        freezetable = freeze_table_age;
        if (freezetable < 0)
            freezetable = vacuum_freeze_table_age;
        freezetable = Min(freezetable, autovacuum_freeze_max_age * 0.95);
        Assert(freezetable >= 0);

        /*
         * Compute XID limit causing a full-table vacuum, being careful not to
         * generate a "permanent" XID.
         */
        limit = ReadNewTransactionId() - freezetable;
        if (!TransactionIdIsNormal(limit))
            limit = FirstNormalTransactionId;

        *xidFullScanLimit = limit;

        /*
         * Similar to the above, determine the table freeze age to use for
         * multixacts: as specified by the caller, or
         * vacuum_multixact_freeze_table_age, but in any case not more than
         * autovacuum_multixact_freeze_table_age * 0.95, so that if you have
         * e.g. nightly VACUUM schedule, the nightly VACUUM gets a chance to
         * freeze multixacts before anti-wraparound autovacuum is launched.
         */
        freezetable = multixact_freeze_table_age;
        if (freezetable < 0)
            freezetable = vacuum_multixact_freeze_table_age;
        freezetable = Min(freezetable,
                          effective_multixact_freeze_max_age * 0.95);
        Assert(freezetable >= 0);

        /*
         * Compute MultiXact limit causing a full-table vacuum, being careful
         * to generate a valid MultiXact value.
         */
        mxactLimit = ReadNextMultiXactId() - freezetable;
        if (mxactLimit < FirstMultiXactId)
            mxactLimit = FirstMultiXactId;

        *mxactFullScanLimit = mxactLimit;
    }
    else
    {
        Assert(mxactFullScanLimit == NULL);
    }
}

Variable Documentation

vac_context

MemoryContext vac_context = NULL

static

Definition at line 66 of file vacuum.c.

vac_strategy

BufferAccessStrategy vac_strategy

static

Definition at line 67 of file vacuum.c.

vacuum_freeze_min_age

int vacuum_freeze_min_age

Definition at line 59 of file vacuum.c.

Referenced by do_autovacuum(), and vacuum_set_xid_limits().

vacuum_freeze_table_age

int vacuum_freeze_table_age

Definition at line 60 of file vacuum.c.

Referenced by do_autovacuum(), and vacuum_set_xid_limits().

vacuum_multixact_freeze_min_age

int vacuum_multixact_freeze_min_age

Definition at line 61 of file vacuum.c.

Referenced by do_autovacuum(), and vacuum_set_xid_limits().

vacuum_multixact_freeze_table_age

int vacuum_multixact_freeze_table_age

Definition at line 62 of file vacuum.c.

Referenced by do_autovacuum(), and vacuum_set_xid_limits().