postgres/src/backend/utils/adt/pgstatfuncs.c
Tom Lane 282d2a03dd HOT updates. When we update a tuple without changing any of its indexed
columns, and the new version can be stored on the same heap page, we no longer
generate extra index entries for the new version.  Instead, index searches
follow the HOT-chain links to ensure they find the correct tuple version.

In addition, this patch introduces the ability to "prune" dead tuples on a
per-page basis, without having to do a complete VACUUM pass to recover space.
VACUUM is still needed to clean up dead index entries, however.

Pavan Deolasee, with help from a bunch of other people.
2007-09-20 17:56:33 +00:00

835 lines
18 KiB
C

/*-------------------------------------------------------------------------
*
* pgstatfuncs.c
* Functions for accessing the statistics collector data
*
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.45 2007/09/20 17:56:31 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "utils/builtins.h"
#include "utils/inet.h"
#include "libpq/ip.h"
/* bogus ... these externs should be in a header file */
extern Datum pg_stat_get_numscans(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_tuples_returned(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_tuples_fetched(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_tuples_inserted(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_tuples_updated(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_tuples_deleted(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_tuples_hot_updated(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_live_tuples(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_dead_tuples(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_blocks_fetched(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_blocks_hit(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_last_vacuum_time(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_last_autovacuum_time(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_last_analyze_time(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_last_autoanalyze_time(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_backend_idset(PG_FUNCTION_ARGS);
extern Datum pg_backend_pid(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_backend_pid(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_backend_dbid(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_backend_userid(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_backend_activity(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_backend_waiting(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_backend_activity_start(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_backend_xact_start(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_backend_start(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_backend_client_addr(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_backend_client_port(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_numbackends(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_xact_commit(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_xact_rollback(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_blocks_fetched(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_blocks_hit(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_tuples_returned(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_tuples_fetched(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_tuples_inserted(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_tuples_updated(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_db_tuples_deleted(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_timed_checkpoints(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_requested_checkpoints(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_buf_written_checkpoints(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_buf_written_clean(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_maxwritten_clean(PG_FUNCTION_ARGS);
extern Datum pg_stat_clear_snapshot(PG_FUNCTION_ARGS);
extern Datum pg_stat_reset(PG_FUNCTION_ARGS);
/* 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_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_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);
}
}
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);
text *result;
PgBackendStatus *beentry;
int len;
const char *activity;
if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
activity = "<backend information not available>";
else if (!superuser() && beentry->st_userid != GetUserId())
activity = "<insufficient privilege>";
else if (*(beentry->st_activity) == '\0')
activity = "<command string not enabled>";
else
activity = beentry->st_activity;
len = strlen(activity);
result = palloc(VARHDRSZ + len);
SET_VARSIZE(result, VARHDRSZ + len);
memcpy(VARDATA(result), activity, len);
PG_RETURN_TEXT_P(result);
}
Datum
pg_stat_get_backend_waiting(PG_FUNCTION_ARGS)
{
int32 beid = PG_GETARG_INT32(0);
bool result;
PgBackendStatus *beentry;
if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
PG_RETURN_NULL();
if (!superuser() && beentry->st_userid != GetUserId())
PG_RETURN_NULL();
result = beentry->st_waiting;
PG_RETURN_BOOL(result);
}
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();
if (!superuser() && beentry->st_userid != GetUserId())
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();
if (!superuser() && beentry->st_userid != GetUserId())
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();
if (!superuser() && beentry->st_userid != GetUserId())
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();
if (!superuser() && beentry->st_userid != GetUserId())
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)
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();
if (!superuser() && beentry->st_userid != GetUserId())
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)
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_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);
}
/* 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();
}