pgstatfuncs.c

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/*-------------------------------------------------------------------------
 *
 * pgstatfuncs.c
 *    Functions for accessing the statistics collector data
 *
 * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/utils/adt/pgstatfuncs.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/htup_details.h"
#include "access/xlog.h"
#include "catalog/pg_authid.h"
#include "catalog/pg_type.h"
#include "common/ip.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "postmaster/bgworker_internals.h"
#include "postmaster/postmaster.h"
#include "storage/proc.h"
#include "storage/procarray.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/inet.h"
#include "utils/timestamp.h"

#define UINT32_ACCESS_ONCE(var)      ((uint32)(*((volatile uint32 *)&(var))))

#define HAS_PGSTAT_PERMISSIONS(role)     (is_member_of_role(GetUserId(), DEFAULT_ROLE_READ_ALL_STATS) || has_privs_of_role(GetUserId(), role))

/* Global bgwriter statistics, from bgwriter.c */
extern PgStat_MsgBgWriter bgwriterStats;

Datum
pg_stat_get_numscans(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->numscans);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_tuples_returned(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->tuples_returned);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_tuples_fetched(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->tuples_fetched);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_tuples_inserted(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->tuples_inserted);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_tuples_updated(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->tuples_updated);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_tuples_deleted(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->tuples_deleted);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_tuples_hot_updated(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->tuples_hot_updated);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_live_tuples(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->n_live_tuples);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_dead_tuples(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->n_dead_tuples);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_mod_since_analyze(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->changes_since_analyze);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_ins_since_vacuum(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->inserts_since_vacuum);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_blocks_fetched(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->blocks_fetched);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_blocks_hit(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->blocks_hit);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_last_vacuum_time(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    TimestampTz result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = tabentry->vacuum_timestamp;

    if (result == 0)
        PG_RETURN_NULL();
    else
        PG_RETURN_TIMESTAMPTZ(result);
}

Datum
pg_stat_get_last_autovacuum_time(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    TimestampTz result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = tabentry->autovac_vacuum_timestamp;

    if (result == 0)
        PG_RETURN_NULL();
    else
        PG_RETURN_TIMESTAMPTZ(result);
}

Datum
pg_stat_get_last_analyze_time(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    TimestampTz result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = tabentry->analyze_timestamp;

    if (result == 0)
        PG_RETURN_NULL();
    else
        PG_RETURN_TIMESTAMPTZ(result);
}

Datum
pg_stat_get_last_autoanalyze_time(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    TimestampTz result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = tabentry->autovac_analyze_timestamp;

    if (result == 0)
        PG_RETURN_NULL();
    else
        PG_RETURN_TIMESTAMPTZ(result);
}

Datum
pg_stat_get_vacuum_count(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->vacuum_count);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_autovacuum_count(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->autovac_vacuum_count);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_analyze_count(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->analyze_count);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_autoanalyze_count(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatTabEntry *tabentry;

    if ((tabentry = pgstat_fetch_stat_tabentry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->autovac_analyze_count);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_function_calls(PG_FUNCTION_ARGS)
{
    Oid         funcid = PG_GETARG_OID(0);
    PgStat_StatFuncEntry *funcentry;

    if ((funcentry = pgstat_fetch_stat_funcentry(funcid)) == NULL)
        PG_RETURN_NULL();
    PG_RETURN_INT64(funcentry->f_numcalls);
}

Datum
pg_stat_get_function_total_time(PG_FUNCTION_ARGS)
{
    Oid         funcid = PG_GETARG_OID(0);
    PgStat_StatFuncEntry *funcentry;

    if ((funcentry = pgstat_fetch_stat_funcentry(funcid)) == NULL)
        PG_RETURN_NULL();
    /* convert counter from microsec to millisec for display */
    PG_RETURN_FLOAT8(((double) funcentry->f_total_time) / 1000.0);
}

Datum
pg_stat_get_function_self_time(PG_FUNCTION_ARGS)
{
    Oid         funcid = PG_GETARG_OID(0);
    PgStat_StatFuncEntry *funcentry;

    if ((funcentry = pgstat_fetch_stat_funcentry(funcid)) == NULL)
        PG_RETURN_NULL();
    /* convert counter from microsec to millisec for display */
    PG_RETURN_FLOAT8(((double) funcentry->f_self_time) / 1000.0);
}

Datum
pg_stat_get_backend_idset(PG_FUNCTION_ARGS)
{
    FuncCallContext *funcctx;
    int        *fctx;
    int32       result;

    /* stuff done only on the first call of the function */
    if (SRF_IS_FIRSTCALL())
    {
        /* create a function context for cross-call persistence */
        funcctx = SRF_FIRSTCALL_INIT();

        fctx = MemoryContextAlloc(funcctx->multi_call_memory_ctx,
                                  2 * sizeof(int));
        funcctx->user_fctx = fctx;

        fctx[0] = 0;
        fctx[1] = pgstat_fetch_stat_numbackends();
    }

    /* stuff done on every call of the function */
    funcctx = SRF_PERCALL_SETUP();
    fctx = funcctx->user_fctx;

    fctx[0] += 1;
    result = fctx[0];

    if (result <= fctx[1])
    {
        /* do when there is more left to send */
        SRF_RETURN_NEXT(funcctx, Int32GetDatum(result));
    }
    else
    {
        /* do when there is no more left */
        SRF_RETURN_DONE(funcctx);
    }
}

/*
 * Returns command progress information for the named command.
 */
Datum
pg_stat_get_progress_info(PG_FUNCTION_ARGS)
{
#define PG_STAT_GET_PROGRESS_COLS   PGSTAT_NUM_PROGRESS_PARAM + 3
    int         num_backends = pgstat_fetch_stat_numbackends();
    int         curr_backend;
    char       *cmd = text_to_cstring(PG_GETARG_TEXT_PP(0));
    ProgressCommandType cmdtype;
    TupleDesc   tupdesc;
    Tuplestorestate *tupstore;
    ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
    MemoryContext per_query_ctx;
    MemoryContext oldcontext;

    /* check to see if caller supports us returning a tuplestore */
    if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("set-valued function called in context that cannot accept a set")));
    if (!(rsinfo->allowedModes & SFRM_Materialize))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("materialize mode required, but it is not allowed in this context")));

    /* Build a tuple descriptor for our result type */
    if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
        elog(ERROR, "return type must be a row type");

    /* Translate command name into command type code. */
    if (pg_strcasecmp(cmd, "VACUUM") == 0)
        cmdtype = PROGRESS_COMMAND_VACUUM;
    else if (pg_strcasecmp(cmd, "ANALYZE") == 0)
        cmdtype = PROGRESS_COMMAND_ANALYZE;
    else if (pg_strcasecmp(cmd, "CLUSTER") == 0)
        cmdtype = PROGRESS_COMMAND_CLUSTER;
    else if (pg_strcasecmp(cmd, "CREATE INDEX") == 0)
        cmdtype = PROGRESS_COMMAND_CREATE_INDEX;
    else if (pg_strcasecmp(cmd, "BASEBACKUP") == 0)
        cmdtype = PROGRESS_COMMAND_BASEBACKUP;
    else
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("invalid command name: \"%s\"", cmd)));

    per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
    oldcontext = MemoryContextSwitchTo(per_query_ctx);

    tupstore = tuplestore_begin_heap(true, false, work_mem);
    rsinfo->returnMode = SFRM_Materialize;
    rsinfo->setResult = tupstore;
    rsinfo->setDesc = tupdesc;
    MemoryContextSwitchTo(oldcontext);

    /* 1-based index */
    for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
    {
        LocalPgBackendStatus *local_beentry;
        PgBackendStatus *beentry;
        Datum       values[PG_STAT_GET_PROGRESS_COLS];
        bool        nulls[PG_STAT_GET_PROGRESS_COLS];
        int         i;

        MemSet(values, 0, sizeof(values));
        MemSet(nulls, 0, sizeof(nulls));

        local_beentry = pgstat_fetch_stat_local_beentry(curr_backend);

        if (!local_beentry)
            continue;

        beentry = &local_beentry->backendStatus;

        /*
         * Report values for only those backends which are running the given
         * command.
         */
        if (!beentry || beentry->st_progress_command != cmdtype)
            continue;

        /* Value available to all callers */
        values[0] = Int32GetDatum(beentry->st_procpid);
        values[1] = ObjectIdGetDatum(beentry->st_databaseid);

        /* show rest of the values including relid only to role members */
        if (HAS_PGSTAT_PERMISSIONS(beentry->st_userid))
        {
            values[2] = ObjectIdGetDatum(beentry->st_progress_command_target);
            for (i = 0; i < PGSTAT_NUM_PROGRESS_PARAM; i++)
                values[i + 3] = Int64GetDatum(beentry->st_progress_param[i]);
        }
        else
        {
            nulls[2] = true;
            for (i = 0; i < PGSTAT_NUM_PROGRESS_PARAM; i++)
                nulls[i + 3] = true;
        }

        tuplestore_putvalues(tupstore, tupdesc, values, nulls);
    }

    /* clean up and return the tuplestore */
    tuplestore_donestoring(tupstore);

    return (Datum) 0;
}

/*
 * Returns activity of PG backends.
 */
Datum
pg_stat_get_activity(PG_FUNCTION_ARGS)
{
#define PG_STAT_GET_ACTIVITY_COLS   30
    int         num_backends = pgstat_fetch_stat_numbackends();
    int         curr_backend;
    int         pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
    ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
    TupleDesc   tupdesc;
    Tuplestorestate *tupstore;
    MemoryContext per_query_ctx;
    MemoryContext oldcontext;

    /* check to see if caller supports us returning a tuplestore */
    if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("set-valued function called in context that cannot accept a set")));
    if (!(rsinfo->allowedModes & SFRM_Materialize))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("materialize mode required, but it is not allowed in this context")));

    /* Build a tuple descriptor for our result type */
    if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
        elog(ERROR, "return type must be a row type");

    per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
    oldcontext = MemoryContextSwitchTo(per_query_ctx);

    tupstore = tuplestore_begin_heap(true, false, work_mem);
    rsinfo->returnMode = SFRM_Materialize;
    rsinfo->setResult = tupstore;
    rsinfo->setDesc = tupdesc;

    MemoryContextSwitchTo(oldcontext);

    /* 1-based index */
    for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
    {
        /* for each row */
        Datum       values[PG_STAT_GET_ACTIVITY_COLS];
        bool        nulls[PG_STAT_GET_ACTIVITY_COLS];
        LocalPgBackendStatus *local_beentry;
        PgBackendStatus *beentry;
        PGPROC     *proc;
        const char *wait_event_type = NULL;
        const char *wait_event = NULL;

        MemSet(values, 0, sizeof(values));
        MemSet(nulls, 0, sizeof(nulls));

        /* Get the next one in the list */
        local_beentry = pgstat_fetch_stat_local_beentry(curr_backend);
        if (!local_beentry)
        {
            int         i;

            /* Ignore missing entries if looking for specific PID */
            if (pid != -1)
                continue;

            for (i = 0; i < lengthof(nulls); i++)
                nulls[i] = true;

            nulls[5] = false;
            values[5] = CStringGetTextDatum("<backend information not available>");

            tuplestore_putvalues(tupstore, tupdesc, values, nulls);
            continue;
        }

        beentry = &local_beentry->backendStatus;

        /* If looking for specific PID, ignore all the others */
        if (pid != -1 && beentry->st_procpid != pid)
            continue;

        /* Values available to all callers */
        if (beentry->st_databaseid != InvalidOid)
            values[0] = ObjectIdGetDatum(beentry->st_databaseid);
        else
            nulls[0] = true;

        values[1] = Int32GetDatum(beentry->st_procpid);

        if (beentry->st_userid != InvalidOid)
            values[2] = ObjectIdGetDatum(beentry->st_userid);
        else
            nulls[2] = true;

        if (beentry->st_appname)
            values[3] = CStringGetTextDatum(beentry->st_appname);
        else
            nulls[3] = true;

        if (TransactionIdIsValid(local_beentry->backend_xid))
            values[15] = TransactionIdGetDatum(local_beentry->backend_xid);
        else
            nulls[15] = true;

        if (TransactionIdIsValid(local_beentry->backend_xmin))
            values[16] = TransactionIdGetDatum(local_beentry->backend_xmin);
        else
            nulls[16] = true;

        /* Values only available to role member or pg_read_all_stats */
        if (HAS_PGSTAT_PERMISSIONS(beentry->st_userid))
        {
            SockAddr    zero_clientaddr;
            char       *clipped_activity;

            switch (beentry->st_state)
            {
                case STATE_IDLE:
                    values[4] = CStringGetTextDatum("idle");
                    break;
                case STATE_RUNNING:
                    values[4] = CStringGetTextDatum("active");
                    break;
                case STATE_IDLEINTRANSACTION:
                    values[4] = CStringGetTextDatum("idle in transaction");
                    break;
                case STATE_FASTPATH:
                    values[4] = CStringGetTextDatum("fastpath function call");
                    break;
                case STATE_IDLEINTRANSACTION_ABORTED:
                    values[4] = CStringGetTextDatum("idle in transaction (aborted)");
                    break;
                case STATE_DISABLED:
                    values[4] = CStringGetTextDatum("disabled");
                    break;
                case STATE_UNDEFINED:
                    nulls[4] = true;
                    break;
            }

            clipped_activity = pgstat_clip_activity(beentry->st_activity_raw);
            values[5] = CStringGetTextDatum(clipped_activity);
            pfree(clipped_activity);

            /* leader_pid */
            nulls[29] = true;

            proc = BackendPidGetProc(beentry->st_procpid);

            if (proc == NULL && (beentry->st_backendType != B_BACKEND))
            {
                /*
                 * For an auxiliary process, retrieve process info from
                 * AuxiliaryProcs stored in shared-memory.
                 */
                proc = AuxiliaryPidGetProc(beentry->st_procpid);
            }

            /*
             * If a PGPROC entry was retrieved, display wait events and lock
             * group leader information if any.  To avoid extra overhead, no
             * extra lock is being held, so there is no guarantee of
             * consistency across multiple rows.
             */
            if (proc != NULL)
            {
                uint32      raw_wait_event;
                PGPROC     *leader;

                raw_wait_event = UINT32_ACCESS_ONCE(proc->wait_event_info);
                wait_event_type = pgstat_get_wait_event_type(raw_wait_event);
                wait_event = pgstat_get_wait_event(raw_wait_event);

                leader = proc->lockGroupLeader;

                /*
                 * Show the leader only for active parallel workers.  This
                 * leaves the field as NULL for the leader of a parallel
                 * group.
                 */
                if (leader && leader->pid != beentry->st_procpid)
                {
                    values[29] = Int32GetDatum(leader->pid);
                    nulls[29] = false;
                }
            }

            if (wait_event_type)
                values[6] = CStringGetTextDatum(wait_event_type);
            else
                nulls[6] = true;

            if (wait_event)
                values[7] = CStringGetTextDatum(wait_event);
            else
                nulls[7] = true;

            /*
             * Don't expose transaction time for walsenders; it confuses
             * monitoring, particularly because we don't keep the time up-to-
             * date.
             */
            if (beentry->st_xact_start_timestamp != 0 &&
                beentry->st_backendType != B_WAL_SENDER)
                values[8] = TimestampTzGetDatum(beentry->st_xact_start_timestamp);
            else
                nulls[8] = true;

            if (beentry->st_activity_start_timestamp != 0)
                values[9] = TimestampTzGetDatum(beentry->st_activity_start_timestamp);
            else
                nulls[9] = true;

            if (beentry->st_proc_start_timestamp != 0)
                values[10] = TimestampTzGetDatum(beentry->st_proc_start_timestamp);
            else
                nulls[10] = true;

            if (beentry->st_state_start_timestamp != 0)
                values[11] = TimestampTzGetDatum(beentry->st_state_start_timestamp);
            else
                nulls[11] = true;

            /* A zeroed client addr means we don't know */
            memset(&zero_clientaddr, 0, sizeof(zero_clientaddr));
            if (memcmp(&(beentry->st_clientaddr), &zero_clientaddr,
                       sizeof(zero_clientaddr)) == 0)
            {
                nulls[12] = true;
                nulls[13] = true;
                nulls[14] = true;
            }
            else
            {
                if (beentry->st_clientaddr.addr.ss_family == AF_INET
#ifdef HAVE_IPV6
                    || beentry->st_clientaddr.addr.ss_family == AF_INET6
#endif
                    )
                {
                    char        remote_host[NI_MAXHOST];
                    char        remote_port[NI_MAXSERV];
                    int         ret;

                    remote_host[0] = '\0';
                    remote_port[0] = '\0';
                    ret = pg_getnameinfo_all(&beentry->st_clientaddr.addr,
                                             beentry->st_clientaddr.salen,
                                             remote_host, sizeof(remote_host),
                                             remote_port, sizeof(remote_port),
                                             NI_NUMERICHOST | NI_NUMERICSERV);
                    if (ret == 0)
                    {
                        clean_ipv6_addr(beentry->st_clientaddr.addr.ss_family, remote_host);
                        values[12] = DirectFunctionCall1(inet_in,
                                                         CStringGetDatum(remote_host));
                        if (beentry->st_clienthostname &&
                            beentry->st_clienthostname[0])
                            values[13] = CStringGetTextDatum(beentry->st_clienthostname);
                        else
                            nulls[13] = true;
                        values[14] = Int32GetDatum(atoi(remote_port));
                    }
                    else
                    {
                        nulls[12] = true;
                        nulls[13] = true;
                        nulls[14] = true;
                    }
                }
                else if (beentry->st_clientaddr.addr.ss_family == AF_UNIX)
                {
                    /*
                     * Unix sockets always reports NULL for host and -1 for
                     * port, so it's possible to tell the difference to
                     * connections we have no permissions to view, or with
                     * errors.
                     */
                    nulls[12] = true;
                    nulls[13] = true;
                    values[14] = Int32GetDatum(-1);
                }
                else
                {
                    /* Unknown address type, should never happen */
                    nulls[12] = true;
                    nulls[13] = true;
                    nulls[14] = true;
                }
            }
            /* Add backend type */
            if (beentry->st_backendType == B_BG_WORKER)
            {
                const char *bgw_type;

                bgw_type = GetBackgroundWorkerTypeByPid(beentry->st_procpid);
                if (bgw_type)
                    values[17] = CStringGetTextDatum(bgw_type);
                else
                    nulls[17] = true;
            }
            else
                values[17] =
                    CStringGetTextDatum(GetBackendTypeDesc(beentry->st_backendType));

            /* SSL information */
            if (beentry->st_ssl)
            {
                values[18] = BoolGetDatum(true);    /* ssl */
                values[19] = CStringGetTextDatum(beentry->st_sslstatus->ssl_version);
                values[20] = CStringGetTextDatum(beentry->st_sslstatus->ssl_cipher);
                values[21] = Int32GetDatum(beentry->st_sslstatus->ssl_bits);
                values[22] = BoolGetDatum(beentry->st_sslstatus->ssl_compression);

                if (beentry->st_sslstatus->ssl_client_dn[0])
                    values[23] = CStringGetTextDatum(beentry->st_sslstatus->ssl_client_dn);
                else
                    nulls[23] = true;

                if (beentry->st_sslstatus->ssl_client_serial[0])
                    values[24] = DirectFunctionCall3(numeric_in,
                                                     CStringGetDatum(beentry->st_sslstatus->ssl_client_serial),
                                                     ObjectIdGetDatum(InvalidOid),
                                                     Int32GetDatum(-1));
                else
                    nulls[24] = true;

                if (beentry->st_sslstatus->ssl_issuer_dn[0])
                    values[25] = CStringGetTextDatum(beentry->st_sslstatus->ssl_issuer_dn);
                else
                    nulls[25] = true;
            }
            else
            {
                values[18] = BoolGetDatum(false);   /* ssl */
                nulls[19] = nulls[20] = nulls[21] = nulls[22] = nulls[23] = nulls[24] = nulls[25] = true;
            }

            /* GSSAPI information */
            if (beentry->st_gss)
            {
                values[26] = BoolGetDatum(beentry->st_gssstatus->gss_auth); /* gss_auth */
                values[27] = CStringGetTextDatum(beentry->st_gssstatus->gss_princ);
                values[28] = BoolGetDatum(beentry->st_gssstatus->gss_enc);  /* GSS Encryption in use */
            }
            else
            {
                values[26] = BoolGetDatum(false);   /* gss_auth */
                nulls[27] = true;   /* No GSS principal */
                values[28] = BoolGetDatum(false);   /* GSS Encryption not in
                                                     * use */
            }
        }
        else
        {
            /* No permissions to view data about this session */
            values[5] = CStringGetTextDatum("<insufficient privilege>");
            nulls[4] = true;
            nulls[6] = true;
            nulls[7] = true;
            nulls[8] = true;
            nulls[9] = true;
            nulls[10] = true;
            nulls[11] = true;
            nulls[12] = true;
            nulls[13] = true;
            nulls[14] = true;
            nulls[17] = true;
            nulls[18] = true;
            nulls[19] = true;
            nulls[20] = true;
            nulls[21] = true;
            nulls[22] = true;
            nulls[23] = true;
            nulls[24] = true;
            nulls[25] = true;
            nulls[26] = true;
            nulls[27] = true;
            nulls[28] = true;
            nulls[29] = true;
        }

        tuplestore_putvalues(tupstore, tupdesc, values, nulls);

        /* If only a single backend was requested, and we found it, break. */
        if (pid != -1)
            break;
    }

    /* clean up and return the tuplestore */
    tuplestore_donestoring(tupstore);

    return (Datum) 0;
}


Datum
pg_backend_pid(PG_FUNCTION_ARGS)
{
    PG_RETURN_INT32(MyProcPid);
}


Datum
pg_stat_get_backend_pid(PG_FUNCTION_ARGS)
{
    int32       beid = PG_GETARG_INT32(0);
    PgBackendStatus *beentry;

    if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
        PG_RETURN_NULL();

    PG_RETURN_INT32(beentry->st_procpid);
}


Datum
pg_stat_get_backend_dbid(PG_FUNCTION_ARGS)
{
    int32       beid = PG_GETARG_INT32(0);
    PgBackendStatus *beentry;

    if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
        PG_RETURN_NULL();

    PG_RETURN_OID(beentry->st_databaseid);
}


Datum
pg_stat_get_backend_userid(PG_FUNCTION_ARGS)
{
    int32       beid = PG_GETARG_INT32(0);
    PgBackendStatus *beentry;

    if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
        PG_RETURN_NULL();

    PG_RETURN_OID(beentry->st_userid);
}


Datum
pg_stat_get_backend_activity(PG_FUNCTION_ARGS)
{
    int32       beid = PG_GETARG_INT32(0);
    PgBackendStatus *beentry;
    const char *activity;
    char       *clipped_activity;
    text       *ret;

    if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
        activity = "<backend information not available>";
    else if (!HAS_PGSTAT_PERMISSIONS(beentry->st_userid))
        activity = "<insufficient privilege>";
    else if (*(beentry->st_activity_raw) == '\0')
        activity = "<command string not enabled>";
    else
        activity = beentry->st_activity_raw;

    clipped_activity = pgstat_clip_activity(activity);
    ret = cstring_to_text(activity);
    pfree(clipped_activity);

    PG_RETURN_TEXT_P(ret);
}

Datum
pg_stat_get_backend_wait_event_type(PG_FUNCTION_ARGS)
{
    int32       beid = PG_GETARG_INT32(0);
    PgBackendStatus *beentry;
    PGPROC     *proc;
    const char *wait_event_type = NULL;

    if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
        wait_event_type = "<backend information not available>";
    else if (!HAS_PGSTAT_PERMISSIONS(beentry->st_userid))
        wait_event_type = "<insufficient privilege>";
    else if ((proc = BackendPidGetProc(beentry->st_procpid)) != NULL)
        wait_event_type = pgstat_get_wait_event_type(proc->wait_event_info);

    if (!wait_event_type)
        PG_RETURN_NULL();

    PG_RETURN_TEXT_P(cstring_to_text(wait_event_type));
}

Datum
pg_stat_get_backend_wait_event(PG_FUNCTION_ARGS)
{
    int32       beid = PG_GETARG_INT32(0);
    PgBackendStatus *beentry;
    PGPROC     *proc;
    const char *wait_event = NULL;

    if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
        wait_event = "<backend information not available>";
    else if (!HAS_PGSTAT_PERMISSIONS(beentry->st_userid))
        wait_event = "<insufficient privilege>";
    else if ((proc = BackendPidGetProc(beentry->st_procpid)) != NULL)
        wait_event = pgstat_get_wait_event(proc->wait_event_info);

    if (!wait_event)
        PG_RETURN_NULL();

    PG_RETURN_TEXT_P(cstring_to_text(wait_event));
}


Datum
pg_stat_get_backend_activity_start(PG_FUNCTION_ARGS)
{
    int32       beid = PG_GETARG_INT32(0);
    TimestampTz result;
    PgBackendStatus *beentry;

    if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
        PG_RETURN_NULL();

    else if (!HAS_PGSTAT_PERMISSIONS(beentry->st_userid))
        PG_RETURN_NULL();

    result = beentry->st_activity_start_timestamp;

    /*
     * No time recorded for start of current query -- this is the case if the
     * user hasn't enabled query-level stats collection.
     */
    if (result == 0)
        PG_RETURN_NULL();

    PG_RETURN_TIMESTAMPTZ(result);
}


Datum
pg_stat_get_backend_xact_start(PG_FUNCTION_ARGS)
{
    int32       beid = PG_GETARG_INT32(0);
    TimestampTz result;
    PgBackendStatus *beentry;

    if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
        PG_RETURN_NULL();

    else if (!HAS_PGSTAT_PERMISSIONS(beentry->st_userid))
        PG_RETURN_NULL();

    result = beentry->st_xact_start_timestamp;

    if (result == 0)            /* not in a transaction */
        PG_RETURN_NULL();

    PG_RETURN_TIMESTAMPTZ(result);
}


Datum
pg_stat_get_backend_start(PG_FUNCTION_ARGS)
{
    int32       beid = PG_GETARG_INT32(0);
    TimestampTz result;
    PgBackendStatus *beentry;

    if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
        PG_RETURN_NULL();

    else if (!HAS_PGSTAT_PERMISSIONS(beentry->st_userid))
        PG_RETURN_NULL();

    result = beentry->st_proc_start_timestamp;

    if (result == 0)            /* probably can't happen? */
        PG_RETURN_NULL();

    PG_RETURN_TIMESTAMPTZ(result);
}


Datum
pg_stat_get_backend_client_addr(PG_FUNCTION_ARGS)
{
    int32       beid = PG_GETARG_INT32(0);
    PgBackendStatus *beentry;
    SockAddr    zero_clientaddr;
    char        remote_host[NI_MAXHOST];
    int         ret;

    if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
        PG_RETURN_NULL();

    else if (!HAS_PGSTAT_PERMISSIONS(beentry->st_userid))
        PG_RETURN_NULL();

    /* A zeroed client addr means we don't know */
    memset(&zero_clientaddr, 0, sizeof(zero_clientaddr));
    if (memcmp(&(beentry->st_clientaddr), &zero_clientaddr,
               sizeof(zero_clientaddr)) == 0)
        PG_RETURN_NULL();

    switch (beentry->st_clientaddr.addr.ss_family)
    {
        case AF_INET:
#ifdef HAVE_IPV6
        case AF_INET6:
#endif
            break;
        default:
            PG_RETURN_NULL();
    }

    remote_host[0] = '\0';
    ret = pg_getnameinfo_all(&beentry->st_clientaddr.addr,
                             beentry->st_clientaddr.salen,
                             remote_host, sizeof(remote_host),
                             NULL, 0,
                             NI_NUMERICHOST | NI_NUMERICSERV);
    if (ret != 0)
        PG_RETURN_NULL();

    clean_ipv6_addr(beentry->st_clientaddr.addr.ss_family, remote_host);

    PG_RETURN_INET_P(DirectFunctionCall1(inet_in,
                                         CStringGetDatum(remote_host)));
}

Datum
pg_stat_get_backend_client_port(PG_FUNCTION_ARGS)
{
    int32       beid = PG_GETARG_INT32(0);
    PgBackendStatus *beentry;
    SockAddr    zero_clientaddr;
    char        remote_port[NI_MAXSERV];
    int         ret;

    if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
        PG_RETURN_NULL();

    else if (!HAS_PGSTAT_PERMISSIONS(beentry->st_userid))
        PG_RETURN_NULL();

    /* A zeroed client addr means we don't know */
    memset(&zero_clientaddr, 0, sizeof(zero_clientaddr));
    if (memcmp(&(beentry->st_clientaddr), &zero_clientaddr,
               sizeof(zero_clientaddr)) == 0)
        PG_RETURN_NULL();

    switch (beentry->st_clientaddr.addr.ss_family)
    {
        case AF_INET:
#ifdef HAVE_IPV6
        case AF_INET6:
#endif
            break;
        case AF_UNIX:
            PG_RETURN_INT32(-1);
        default:
            PG_RETURN_NULL();
    }

    remote_port[0] = '\0';
    ret = pg_getnameinfo_all(&beentry->st_clientaddr.addr,
                             beentry->st_clientaddr.salen,
                             NULL, 0,
                             remote_port, sizeof(remote_port),
                             NI_NUMERICHOST | NI_NUMERICSERV);
    if (ret != 0)
        PG_RETURN_NULL();

    PG_RETURN_DATUM(DirectFunctionCall1(int4in,
                                        CStringGetDatum(remote_port)));
}


Datum
pg_stat_get_db_numbackends(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int32       result;
    int         tot_backends = pgstat_fetch_stat_numbackends();
    int         beid;

    result = 0;
    for (beid = 1; beid <= tot_backends; beid++)
    {
        PgBackendStatus *beentry = pgstat_fetch_stat_beentry(beid);

        if (beentry && beentry->st_databaseid == dbid)
            result++;
    }

    PG_RETURN_INT32(result);
}


Datum
pg_stat_get_db_xact_commit(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_xact_commit);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_db_xact_rollback(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_xact_rollback);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_db_blocks_fetched(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_blocks_fetched);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_db_blocks_hit(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_blocks_hit);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_db_tuples_returned(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_tuples_returned);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_db_tuples_fetched(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_tuples_fetched);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_db_tuples_inserted(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_tuples_inserted);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_db_tuples_updated(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_tuples_updated);

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_db_tuples_deleted(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_tuples_deleted);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_db_stat_reset_time(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    TimestampTz result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = dbentry->stat_reset_timestamp;

    if (result == 0)
        PG_RETURN_NULL();
    else
        PG_RETURN_TIMESTAMPTZ(result);
}

Datum
pg_stat_get_db_temp_files(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = dbentry->n_temp_files;

    PG_RETURN_INT64(result);
}


Datum
pg_stat_get_db_temp_bytes(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = dbentry->n_temp_bytes;

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_db_conflict_tablespace(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_conflict_tablespace);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_db_conflict_lock(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_conflict_lock);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_db_conflict_snapshot(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_conflict_snapshot);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_db_conflict_bufferpin(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_conflict_bufferpin);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_db_conflict_startup_deadlock(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_conflict_startup_deadlock);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_db_conflict_all(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_conflict_tablespace +
                          dbentry->n_conflict_lock +
                          dbentry->n_conflict_snapshot +
                          dbentry->n_conflict_bufferpin +
                          dbentry->n_conflict_startup_deadlock);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_db_deadlocks(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_deadlocks);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_db_checksum_failures(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    int64       result;
    PgStat_StatDBEntry *dbentry;

    if (!DataChecksumsEnabled())
        PG_RETURN_NULL();

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = (int64) (dbentry->n_checksum_failures);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_db_checksum_last_failure(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    TimestampTz result;
    PgStat_StatDBEntry *dbentry;

    if (!DataChecksumsEnabled())
        PG_RETURN_NULL();

    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = dbentry->last_checksum_failure;

    if (result == 0)
        PG_RETURN_NULL();
    else
        PG_RETURN_TIMESTAMPTZ(result);
}

Datum
pg_stat_get_db_blk_read_time(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    double      result;
    PgStat_StatDBEntry *dbentry;

    /* convert counter from microsec to millisec for display */
    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = ((double) dbentry->n_block_read_time) / 1000.0;

    PG_RETURN_FLOAT8(result);
}

Datum
pg_stat_get_db_blk_write_time(PG_FUNCTION_ARGS)
{
    Oid         dbid = PG_GETARG_OID(0);
    double      result;
    PgStat_StatDBEntry *dbentry;

    /* convert counter from microsec to millisec for display */
    if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
        result = 0;
    else
        result = ((double) dbentry->n_block_write_time) / 1000.0;

    PG_RETURN_FLOAT8(result);
}

Datum
pg_stat_get_bgwriter_timed_checkpoints(PG_FUNCTION_ARGS)
{
    PG_RETURN_INT64(pgstat_fetch_global()->timed_checkpoints);
}

Datum
pg_stat_get_bgwriter_requested_checkpoints(PG_FUNCTION_ARGS)
{
    PG_RETURN_INT64(pgstat_fetch_global()->requested_checkpoints);
}

Datum
pg_stat_get_bgwriter_buf_written_checkpoints(PG_FUNCTION_ARGS)
{
    PG_RETURN_INT64(pgstat_fetch_global()->buf_written_checkpoints);
}

Datum
pg_stat_get_bgwriter_buf_written_clean(PG_FUNCTION_ARGS)
{
    PG_RETURN_INT64(pgstat_fetch_global()->buf_written_clean);
}

Datum
pg_stat_get_bgwriter_maxwritten_clean(PG_FUNCTION_ARGS)
{
    PG_RETURN_INT64(pgstat_fetch_global()->maxwritten_clean);
}

Datum
pg_stat_get_checkpoint_write_time(PG_FUNCTION_ARGS)
{
    /* time is already in msec, just convert to double for presentation */
    PG_RETURN_FLOAT8((double) pgstat_fetch_global()->checkpoint_write_time);
}

Datum
pg_stat_get_checkpoint_sync_time(PG_FUNCTION_ARGS)
{
    /* time is already in msec, just convert to double for presentation */
    PG_RETURN_FLOAT8((double) pgstat_fetch_global()->checkpoint_sync_time);
}

Datum
pg_stat_get_bgwriter_stat_reset_time(PG_FUNCTION_ARGS)
{
    PG_RETURN_TIMESTAMPTZ(pgstat_fetch_global()->stat_reset_timestamp);
}

Datum
pg_stat_get_buf_written_backend(PG_FUNCTION_ARGS)
{
    PG_RETURN_INT64(pgstat_fetch_global()->buf_written_backend);
}

Datum
pg_stat_get_buf_fsync_backend(PG_FUNCTION_ARGS)
{
    PG_RETURN_INT64(pgstat_fetch_global()->buf_fsync_backend);
}

Datum
pg_stat_get_buf_alloc(PG_FUNCTION_ARGS)
{
    PG_RETURN_INT64(pgstat_fetch_global()->buf_alloc);
}

/*
 * Returns statistics of SLRU caches.
 */
Datum
pg_stat_get_slru(PG_FUNCTION_ARGS)
{
#define PG_STAT_GET_SLRU_COLS   9
    ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
    TupleDesc   tupdesc;
    Tuplestorestate *tupstore;
    MemoryContext per_query_ctx;
    MemoryContext oldcontext;
    int         i;
    PgStat_SLRUStats *stats;

    /* check to see if caller supports us returning a tuplestore */
    if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("set-valued function called in context that cannot accept a set")));
    if (!(rsinfo->allowedModes & SFRM_Materialize))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("materialize mode required, but it is not allowed in this context")));

    /* Build a tuple descriptor for our result type */
    if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
        elog(ERROR, "return type must be a row type");

    per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
    oldcontext = MemoryContextSwitchTo(per_query_ctx);

    tupstore = tuplestore_begin_heap(true, false, work_mem);
    rsinfo->returnMode = SFRM_Materialize;
    rsinfo->setResult = tupstore;
    rsinfo->setDesc = tupdesc;

    MemoryContextSwitchTo(oldcontext);

    /* request SLRU stats from the stat collector */
    stats = pgstat_fetch_slru();

    for (i = 0;; i++)
    {
        /* for each row */
        Datum       values[PG_STAT_GET_SLRU_COLS];
        bool        nulls[PG_STAT_GET_SLRU_COLS];
        PgStat_SLRUStats stat = stats[i];
        const char *name;

        name = pgstat_slru_name(i);

        if (!name)
            break;

        MemSet(values, 0, sizeof(values));
        MemSet(nulls, 0, sizeof(nulls));

        values[0] = PointerGetDatum(cstring_to_text(name));
        values[1] = Int64GetDatum(stat.blocks_zeroed);
        values[2] = Int64GetDatum(stat.blocks_hit);
        values[3] = Int64GetDatum(stat.blocks_read);
        values[4] = Int64GetDatum(stat.blocks_written);
        values[5] = Int64GetDatum(stat.blocks_exists);
        values[6] = Int64GetDatum(stat.flush);
        values[7] = Int64GetDatum(stat.truncate);
        values[8] = TimestampTzGetDatum(stat.stat_reset_timestamp);

        tuplestore_putvalues(tupstore, tupdesc, values, nulls);
    }

    /* clean up and return the tuplestore */
    tuplestore_donestoring(tupstore);

    return (Datum) 0;
}

Datum
pg_stat_get_xact_numscans(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_TableStatus *tabentry;

    if ((tabentry = find_tabstat_entry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->t_counts.t_numscans);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_xact_tuples_returned(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_TableStatus *tabentry;

    if ((tabentry = find_tabstat_entry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->t_counts.t_tuples_returned);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_xact_tuples_fetched(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_TableStatus *tabentry;

    if ((tabentry = find_tabstat_entry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->t_counts.t_tuples_fetched);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_xact_tuples_inserted(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_TableStatus *tabentry;
    PgStat_TableXactStatus *trans;

    if ((tabentry = find_tabstat_entry(relid)) == NULL)
        result = 0;
    else
    {
        result = tabentry->t_counts.t_tuples_inserted;
        /* live subtransactions' counts aren't in t_tuples_inserted yet */
        for (trans = tabentry->trans; trans != NULL; trans = trans->upper)
            result += trans->tuples_inserted;
    }

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_xact_tuples_updated(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_TableStatus *tabentry;
    PgStat_TableXactStatus *trans;

    if ((tabentry = find_tabstat_entry(relid)) == NULL)
        result = 0;
    else
    {
        result = tabentry->t_counts.t_tuples_updated;
        /* live subtransactions' counts aren't in t_tuples_updated yet */
        for (trans = tabentry->trans; trans != NULL; trans = trans->upper)
            result += trans->tuples_updated;
    }

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_xact_tuples_deleted(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_TableStatus *tabentry;
    PgStat_TableXactStatus *trans;

    if ((tabentry = find_tabstat_entry(relid)) == NULL)
        result = 0;
    else
    {
        result = tabentry->t_counts.t_tuples_deleted;
        /* live subtransactions' counts aren't in t_tuples_deleted yet */
        for (trans = tabentry->trans; trans != NULL; trans = trans->upper)
            result += trans->tuples_deleted;
    }

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_xact_tuples_hot_updated(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_TableStatus *tabentry;

    if ((tabentry = find_tabstat_entry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->t_counts.t_tuples_hot_updated);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_xact_blocks_fetched(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_TableStatus *tabentry;

    if ((tabentry = find_tabstat_entry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->t_counts.t_blocks_fetched);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_xact_blocks_hit(PG_FUNCTION_ARGS)
{
    Oid         relid = PG_GETARG_OID(0);
    int64       result;
    PgStat_TableStatus *tabentry;

    if ((tabentry = find_tabstat_entry(relid)) == NULL)
        result = 0;
    else
        result = (int64) (tabentry->t_counts.t_blocks_hit);

    PG_RETURN_INT64(result);
}

Datum
pg_stat_get_xact_function_calls(PG_FUNCTION_ARGS)
{
    Oid         funcid = PG_GETARG_OID(0);
    PgStat_BackendFunctionEntry *funcentry;

    if ((funcentry = find_funcstat_entry(funcid)) == NULL)
        PG_RETURN_NULL();
    PG_RETURN_INT64(funcentry->f_counts.f_numcalls);
}

Datum
pg_stat_get_xact_function_total_time(PG_FUNCTION_ARGS)
{
    Oid         funcid = PG_GETARG_OID(0);
    PgStat_BackendFunctionEntry *funcentry;

    if ((funcentry = find_funcstat_entry(funcid)) == NULL)
        PG_RETURN_NULL();
    PG_RETURN_FLOAT8(INSTR_TIME_GET_MILLISEC(funcentry->f_counts.f_total_time));
}

Datum
pg_stat_get_xact_function_self_time(PG_FUNCTION_ARGS)
{
    Oid         funcid = PG_GETARG_OID(0);
    PgStat_BackendFunctionEntry *funcentry;

    if ((funcentry = find_funcstat_entry(funcid)) == NULL)
        PG_RETURN_NULL();
    PG_RETURN_FLOAT8(INSTR_TIME_GET_MILLISEC(funcentry->f_counts.f_self_time));
}


/* Get the timestamp of the current statistics snapshot */
Datum
pg_stat_get_snapshot_timestamp(PG_FUNCTION_ARGS)
{
    PG_RETURN_TIMESTAMPTZ(pgstat_fetch_global()->stats_timestamp);
}

/* Discard the active statistics snapshot */
Datum
pg_stat_clear_snapshot(PG_FUNCTION_ARGS)
{
    pgstat_clear_snapshot();

    PG_RETURN_VOID();
}


/* Reset all counters for the current database */
Datum
pg_stat_reset(PG_FUNCTION_ARGS)
{
    pgstat_reset_counters();

    PG_RETURN_VOID();
}

/* Reset some shared cluster-wide counters */
Datum
pg_stat_reset_shared(PG_FUNCTION_ARGS)
{
    char       *target = text_to_cstring(PG_GETARG_TEXT_PP(0));

    pgstat_reset_shared_counters(target);

    PG_RETURN_VOID();
}

/* Reset a single counter in the current database */
Datum
pg_stat_reset_single_table_counters(PG_FUNCTION_ARGS)
{
    Oid         taboid = PG_GETARG_OID(0);

    pgstat_reset_single_counter(taboid, RESET_TABLE);

    PG_RETURN_VOID();
}

Datum
pg_stat_reset_single_function_counters(PG_FUNCTION_ARGS)
{
    Oid         funcoid = PG_GETARG_OID(0);

    pgstat_reset_single_counter(funcoid, RESET_FUNCTION);

    PG_RETURN_VOID();
}

/* Reset SLRU counters (a specific one or all of them). */
Datum
pg_stat_reset_slru(PG_FUNCTION_ARGS)
{
    char       *target = NULL;

    if (!PG_ARGISNULL(0))
        target = text_to_cstring(PG_GETARG_TEXT_PP(0));

    pgstat_reset_slru_counter(target);

    PG_RETURN_VOID();
}

Datum
pg_stat_get_archiver(PG_FUNCTION_ARGS)
{
    TupleDesc   tupdesc;
    Datum       values[7];
    bool        nulls[7];
    PgStat_ArchiverStats *archiver_stats;

    /* Initialise values and NULL flags arrays */
    MemSet(values, 0, sizeof(values));
    MemSet(nulls, 0, sizeof(nulls));

    /* Initialise attributes information in the tuple descriptor */
    tupdesc = CreateTemplateTupleDesc(7);
    TupleDescInitEntry(tupdesc, (AttrNumber) 1, "archived_count",
                       INT8OID, -1, 0);
    TupleDescInitEntry(tupdesc, (AttrNumber) 2, "last_archived_wal",
                       TEXTOID, -1, 0);
    TupleDescInitEntry(tupdesc, (AttrNumber) 3, "last_archived_time",
                       TIMESTAMPTZOID, -1, 0);
    TupleDescInitEntry(tupdesc, (AttrNumber) 4, "failed_count",
                       INT8OID, -1, 0);
    TupleDescInitEntry(tupdesc, (AttrNumber) 5, "last_failed_wal",
                       TEXTOID, -1, 0);
    TupleDescInitEntry(tupdesc, (AttrNumber) 6, "last_failed_time",
                       TIMESTAMPTZOID, -1, 0);
    TupleDescInitEntry(tupdesc, (AttrNumber) 7, "stats_reset",
                       TIMESTAMPTZOID, -1, 0);

    BlessTupleDesc(tupdesc);

    /* Get statistics about the archiver process */
    archiver_stats = pgstat_fetch_stat_archiver();

    /* Fill values and NULLs */
    values[0] = Int64GetDatum(archiver_stats->archived_count);
    if (*(archiver_stats->last_archived_wal) == '\0')
        nulls[1] = true;
    else
        values[1] = CStringGetTextDatum(archiver_stats->last_archived_wal);

    if (archiver_stats->last_archived_timestamp == 0)
        nulls[2] = true;
    else
        values[2] = TimestampTzGetDatum(archiver_stats->last_archived_timestamp);

    values[3] = Int64GetDatum(archiver_stats->failed_count);
    if (*(archiver_stats->last_failed_wal) == '\0')
        nulls[4] = true;
    else
        values[4] = CStringGetTextDatum(archiver_stats->last_failed_wal);

    if (archiver_stats->last_failed_timestamp == 0)
        nulls[5] = true;
    else
        values[5] = TimestampTzGetDatum(archiver_stats->last_failed_timestamp);

    if (archiver_stats->stat_reset_timestamp == 0)
        nulls[6] = true;
    else
        values[6] = TimestampTzGetDatum(archiver_stats->stat_reset_timestamp);

    /* Returns the record as Datum */
    PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
}