/*-------------------------------------------------------------------------
 *
 * 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 1.42 2007/05/17 23:31:49 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_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_txn_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_lru(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_buf_written_all(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_maxwritten_lru(PG_FUNCTION_ARGS);
extern Datum pg_stat_get_bgwriter_maxwritten_all(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_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_txn_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_txn_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_lru(PG_FUNCTION_ARGS)
{
	PG_RETURN_INT64(pgstat_fetch_global()->buf_written_lru);
}

Datum
pg_stat_get_bgwriter_buf_written_all(PG_FUNCTION_ARGS)
{
	PG_RETURN_INT64(pgstat_fetch_global()->buf_written_all);
}

Datum
pg_stat_get_bgwriter_maxwritten_lru(PG_FUNCTION_ARGS)
{
	PG_RETURN_INT64(pgstat_fetch_global()->maxwritten_lru);
}

Datum
pg_stat_get_bgwriter_maxwritten_all(PG_FUNCTION_ARGS)
{
	PG_RETURN_INT64(pgstat_fetch_global()->maxwritten_all);
}


/* 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();
}
