pgstat_database.c

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/* -------------------------------------------------------------------------
 *
 * pgstat_database.c
 *    Implementation of database statistics.
 *
 * This file contains the implementation of database statistics. It is kept
 * separate from pgstat.c to enforce the line between the statistics access /
 * storage implementation and the details about individual types of
 * statistics.
 *
 * Copyright (c) 2001-2025, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *    src/backend/utils/activity/pgstat_database.c
 * -------------------------------------------------------------------------
 */
 
#include "postgres.h"
 
#include "storage/procsignal.h"
#include "utils/pgstat_internal.h"
#include "utils/timestamp.h"
 
 
static bool pgstat_should_report_connstat(void);
 
 
PgStat_Counter pgStatBlockReadTime = 0;
PgStat_Counter pgStatBlockWriteTime = 0;
PgStat_Counter pgStatActiveTime = 0;
PgStat_Counter pgStatTransactionIdleTime = 0;
SessionEndType pgStatSessionEndCause = DISCONNECT_NORMAL;
 
 
static int  pgStatXactCommit = 0;
static int  pgStatXactRollback = 0;
static PgStat_Counter pgLastSessionReportTime = 0;
 
 
/*
 * Remove entry for the database being dropped.
 */
void
pgstat_drop_database(Oid databaseid)
{
    pgstat_drop_transactional(PGSTAT_KIND_DATABASE, databaseid, InvalidOid);
}
 
/*
 * Called from autovacuum.c to report startup of an autovacuum process.
 * We are called before InitPostgres is done, so can't rely on MyDatabaseId;
 * the db OID must be passed in, instead.
 */
void
pgstat_report_autovac(Oid dboid)
{
    PgStat_EntryRef *entry_ref;
    PgStatShared_Database *dbentry;
 
    /* can't get here in single user mode */
    Assert(IsUnderPostmaster);
 
    /*
     * End-of-vacuum is reported instantly. Report the start the same way for
     * consistency. Vacuum doesn't run frequently and is a long-lasting
     * operation so it doesn't matter if we get blocked here a little.
     */
    entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_DATABASE,
                                            dboid, InvalidOid, false);
 
    dbentry = (PgStatShared_Database *) entry_ref->shared_stats;
    dbentry->stats.last_autovac_time = GetCurrentTimestamp();
 
    pgstat_unlock_entry(entry_ref);
}
 
/*
 * Report a Hot Standby recovery conflict.
 */
void
pgstat_report_recovery_conflict(int reason)
{
    PgStat_StatDBEntry *dbentry;
 
    Assert(IsUnderPostmaster);
    if (!pgstat_track_counts)
        return;
 
    dbentry = pgstat_prep_database_pending(MyDatabaseId);
 
    switch (reason)
    {
        case PROCSIG_RECOVERY_CONFLICT_DATABASE:
 
            /*
             * Since we drop the information about the database as soon as it
             * replicates, there is no point in counting these conflicts.
             */
            break;
        case PROCSIG_RECOVERY_CONFLICT_TABLESPACE:
            dbentry->conflict_tablespace++;
            break;
        case PROCSIG_RECOVERY_CONFLICT_LOCK:
            dbentry->conflict_lock++;
            break;
        case PROCSIG_RECOVERY_CONFLICT_SNAPSHOT:
            dbentry->conflict_snapshot++;
            break;
        case PROCSIG_RECOVERY_CONFLICT_BUFFERPIN:
            dbentry->conflict_bufferpin++;
            break;
        case PROCSIG_RECOVERY_CONFLICT_LOGICALSLOT:
            dbentry->conflict_logicalslot++;
            break;
        case PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK:
            dbentry->conflict_startup_deadlock++;
            break;
    }
}
 
/*
 * Report a detected deadlock.
 */
void
pgstat_report_deadlock(void)
{
    PgStat_StatDBEntry *dbent;
 
    if (!pgstat_track_counts)
        return;
 
    dbent = pgstat_prep_database_pending(MyDatabaseId);
    dbent->deadlocks++;
}
 
/*
 * Allow this backend to later report checksum failures for dboid, even if in
 * a critical section at the time of the report.
 *
 * Without this function having been called first, the backend might need to
 * allocate an EntryRef or might need to map in DSM segments. Neither should
 * happen in a critical section.
 */
void
pgstat_prepare_report_checksum_failure(Oid dboid)
{
    Assert(!CritSectionCount);
 
    /*
     * Just need to ensure this backend has an entry ref for the database.
     * That will allows us to report checksum failures without e.g. needing to
     * map in DSM segments.
     */
    pgstat_get_entry_ref(PGSTAT_KIND_DATABASE, dboid, InvalidOid,
                         true, NULL);
}
 
/*
 * Report one or more checksum failures.
 *
 * To be allowed to report checksum failures in critical sections, we require
 * pgstat_prepare_report_checksum_failure() to have been called before this
 * function is called.
 */
void
pgstat_report_checksum_failures_in_db(Oid dboid, int failurecount)
{
    PgStat_EntryRef *entry_ref;
    PgStatShared_Database *sharedent;
 
    if (!pgstat_track_counts)
        return;
 
    /*
     * Update the shared stats directly - checksum failures should never be
     * common enough for that to be a problem. Note that we pass create=false
     * here, as we want to be sure to not require memory allocations, so this
     * can be called in critical sections.
     */
    entry_ref = pgstat_get_entry_ref(PGSTAT_KIND_DATABASE, dboid, InvalidOid,
                                     false, NULL);
 
    /*
     * Should always have been created by
     * pgstat_prepare_report_checksum_failure().
     *
     * When not using assertions, we don't want to crash should something have
     * gone wrong, so just return.
     */
    Assert(entry_ref);
    if (!entry_ref)
    {
        elog(WARNING, "could not report %d conflicts for DB %u",
             failurecount, dboid);
        return;
    }
 
    (void) pgstat_lock_entry(entry_ref, false);
 
    sharedent = (PgStatShared_Database *) entry_ref->shared_stats;
    sharedent->stats.checksum_failures += failurecount;
    sharedent->stats.last_checksum_failure = GetCurrentTimestamp();
 
    pgstat_unlock_entry(entry_ref);
}
 
/*
 * Report creation of temporary file.
 */
void
pgstat_report_tempfile(size_t filesize)
{
    PgStat_StatDBEntry *dbent;
 
    if (!pgstat_track_counts)
        return;
 
    dbent = pgstat_prep_database_pending(MyDatabaseId);
    dbent->temp_bytes += filesize;
    dbent->temp_files++;
}
 
/*
 * Notify stats system of a new connection.
 */
void
pgstat_report_connect(Oid dboid)
{
    PgStat_StatDBEntry *dbentry;
 
    if (!pgstat_should_report_connstat())
        return;
 
    pgLastSessionReportTime = MyStartTimestamp;
 
    dbentry = pgstat_prep_database_pending(MyDatabaseId);
    dbentry->sessions++;
}
 
/*
 * Notify the stats system of a disconnect.
 */
void
pgstat_report_disconnect(Oid dboid)
{
    PgStat_StatDBEntry *dbentry;
 
    if (!pgstat_should_report_connstat())
        return;
 
    dbentry = pgstat_prep_database_pending(MyDatabaseId);
 
    switch (pgStatSessionEndCause)
    {
        case DISCONNECT_NOT_YET:
        case DISCONNECT_NORMAL:
            /* we don't collect these */
            break;
        case DISCONNECT_CLIENT_EOF:
            dbentry->sessions_abandoned++;
            break;
        case DISCONNECT_FATAL:
            dbentry->sessions_fatal++;
            break;
        case DISCONNECT_KILLED:
            dbentry->sessions_killed++;
            break;
    }
}
 
/*
 * Support function for the SQL-callable pgstat* functions. Returns
 * the collected statistics for one database or NULL. NULL doesn't mean
 * that the database doesn't exist, just that there are no statistics, so the
 * caller is better off to report ZERO instead.
 */
PgStat_StatDBEntry *
pgstat_fetch_stat_dbentry(Oid dboid)
{
    return (PgStat_StatDBEntry *)
        pgstat_fetch_entry(PGSTAT_KIND_DATABASE, dboid, InvalidOid);
}
 
void
AtEOXact_PgStat_Database(bool isCommit, bool parallel)
{
    /* Don't count parallel worker transaction stats */
    if (!parallel)
    {
        /*
         * Count transaction commit or abort.  (We use counters, not just
         * bools, in case the reporting message isn't sent right away.)
         */
        if (isCommit)
            pgStatXactCommit++;
        else
            pgStatXactRollback++;
    }
}
 
/*
 * Notify the stats system about parallel worker information.
 */
void
pgstat_update_parallel_workers_stats(PgStat_Counter workers_to_launch,
                                     PgStat_Counter workers_launched)
{
    PgStat_StatDBEntry *dbentry;
 
    if (!OidIsValid(MyDatabaseId))
        return;
 
    dbentry = pgstat_prep_database_pending(MyDatabaseId);
    dbentry->parallel_workers_to_launch += workers_to_launch;
    dbentry->parallel_workers_launched += workers_launched;
}
 
/*
 * Subroutine for pgstat_report_stat(): Handle xact commit/rollback and I/O
 * timings.
 */
void
pgstat_update_dbstats(TimestampTz ts)
{
    PgStat_StatDBEntry *dbentry;
 
    /*
     * If not connected to a database yet, don't attribute time to "shared
     * state" (InvalidOid is used to track stats for shared relations, etc.).
     */
    if (!OidIsValid(MyDatabaseId))
        return;
 
    dbentry = pgstat_prep_database_pending(MyDatabaseId);
 
    /*
     * Accumulate xact commit/rollback and I/O timings to stats entry of the
     * current database.
     */
    dbentry->xact_commit += pgStatXactCommit;
    dbentry->xact_rollback += pgStatXactRollback;
    dbentry->blk_read_time += pgStatBlockReadTime;
    dbentry->blk_write_time += pgStatBlockWriteTime;
 
    if (pgstat_should_report_connstat())
    {
        long        secs;
        int         usecs;
 
        /*
         * pgLastSessionReportTime is initialized to MyStartTimestamp by
         * pgstat_report_connect().
         */
        TimestampDifference(pgLastSessionReportTime, ts, &secs, &usecs);
        pgLastSessionReportTime = ts;
        dbentry->session_time += (PgStat_Counter) secs * 1000000 + usecs;
        dbentry->active_time += pgStatActiveTime;
        dbentry->idle_in_transaction_time += pgStatTransactionIdleTime;
    }
 
    pgStatXactCommit = 0;
    pgStatXactRollback = 0;
    pgStatBlockReadTime = 0;
    pgStatBlockWriteTime = 0;
    pgStatActiveTime = 0;
    pgStatTransactionIdleTime = 0;
}
 
/*
 * We report session statistics only for normal backend processes.  Parallel
 * workers run in parallel, so they don't contribute to session times, even
 * though they use CPU time. Walsender processes could be considered here,
 * but they have different session characteristics from normal backends (for
 * example, they are always "active"), so they would skew session statistics.
 */
static bool
pgstat_should_report_connstat(void)
{
    return MyBackendType == B_BACKEND;
}
 
/*
 * Find or create a local PgStat_StatDBEntry entry for dboid.
 */
PgStat_StatDBEntry *
pgstat_prep_database_pending(Oid dboid)
{
    PgStat_EntryRef *entry_ref;
 
    /*
     * This should not report stats on database objects before having
     * connected to a database.
     */
    Assert(!OidIsValid(dboid) || OidIsValid(MyDatabaseId));
 
    entry_ref = pgstat_prep_pending_entry(PGSTAT_KIND_DATABASE, dboid, InvalidOid,
                                          NULL);
 
    return entry_ref->pending;
}
 
/*
 * Reset the database's reset timestamp, without resetting the contents of the
 * database stats.
 */
void
pgstat_reset_database_timestamp(Oid dboid, TimestampTz ts)
{
    PgStat_EntryRef *dbref;
    PgStatShared_Database *dbentry;
 
    dbref = pgstat_get_entry_ref_locked(PGSTAT_KIND_DATABASE, MyDatabaseId, InvalidOid,
                                        false);
 
    dbentry = (PgStatShared_Database *) dbref->shared_stats;
    dbentry->stats.stat_reset_timestamp = ts;
 
    pgstat_unlock_entry(dbref);
}
 
/*
 * Flush out pending stats for the entry
 *
 * If nowait is true, this function returns false if lock could not
 * immediately acquired, otherwise true is returned.
 */
bool
pgstat_database_flush_cb(PgStat_EntryRef *entry_ref, bool nowait)
{
    PgStatShared_Database *sharedent;
    PgStat_StatDBEntry *pendingent;
 
    pendingent = (PgStat_StatDBEntry *) entry_ref->pending;
    sharedent = (PgStatShared_Database *) entry_ref->shared_stats;
 
    if (!pgstat_lock_entry(entry_ref, nowait))
        return false;
 
#define PGSTAT_ACCUM_DBCOUNT(item)      \
    (sharedent)->stats.item += (pendingent)->item
 
    PGSTAT_ACCUM_DBCOUNT(xact_commit);
    PGSTAT_ACCUM_DBCOUNT(xact_rollback);
    PGSTAT_ACCUM_DBCOUNT(blocks_fetched);
    PGSTAT_ACCUM_DBCOUNT(blocks_hit);
 
    PGSTAT_ACCUM_DBCOUNT(tuples_returned);
    PGSTAT_ACCUM_DBCOUNT(tuples_fetched);
    PGSTAT_ACCUM_DBCOUNT(tuples_inserted);
    PGSTAT_ACCUM_DBCOUNT(tuples_updated);
    PGSTAT_ACCUM_DBCOUNT(tuples_deleted);
 
    /* last_autovac_time is reported immediately */
    Assert(pendingent->last_autovac_time == 0);
 
    PGSTAT_ACCUM_DBCOUNT(conflict_tablespace);
    PGSTAT_ACCUM_DBCOUNT(conflict_lock);
    PGSTAT_ACCUM_DBCOUNT(conflict_snapshot);
    PGSTAT_ACCUM_DBCOUNT(conflict_logicalslot);
    PGSTAT_ACCUM_DBCOUNT(conflict_bufferpin);
    PGSTAT_ACCUM_DBCOUNT(conflict_startup_deadlock);
 
    PGSTAT_ACCUM_DBCOUNT(temp_bytes);
    PGSTAT_ACCUM_DBCOUNT(temp_files);
    PGSTAT_ACCUM_DBCOUNT(deadlocks);
 
    /* checksum failures are reported immediately */
    Assert(pendingent->checksum_failures == 0);
    Assert(pendingent->last_checksum_failure == 0);
 
    PGSTAT_ACCUM_DBCOUNT(blk_read_time);
    PGSTAT_ACCUM_DBCOUNT(blk_write_time);
 
    PGSTAT_ACCUM_DBCOUNT(sessions);
    PGSTAT_ACCUM_DBCOUNT(session_time);
    PGSTAT_ACCUM_DBCOUNT(active_time);
    PGSTAT_ACCUM_DBCOUNT(idle_in_transaction_time);
    PGSTAT_ACCUM_DBCOUNT(sessions_abandoned);
    PGSTAT_ACCUM_DBCOUNT(sessions_fatal);
    PGSTAT_ACCUM_DBCOUNT(sessions_killed);
    PGSTAT_ACCUM_DBCOUNT(parallel_workers_to_launch);
    PGSTAT_ACCUM_DBCOUNT(parallel_workers_launched);
#undef PGSTAT_ACCUM_DBCOUNT
 
    pgstat_unlock_entry(entry_ref);
 
    memset(pendingent, 0, sizeof(*pendingent));
 
    return true;
}
 
void
pgstat_database_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
{
    ((PgStatShared_Database *) header)->stats.stat_reset_timestamp = ts;
}