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pgstat: add WAL receiver status view & SRF

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This new view provides insight into the state of a running WAL receiver
in a HOT standby node.
The information returned includes the PID of the WAL receiver process,
its status (stopped, starting, streaming, etc), start LSN and TLI, last
received LSN and TLI, timestamp of last message send and receipt, latest
end-of-WAL LSN and time, and the name of the slot (if any).

Access to the detailed data is only granted to superusers; others only
get the PID.

Author: Michael Paquier
Reviewer: Haribabu Kommi
This commit is contained in:
Alvaro Herrera
2016-01-07 16:21:19 -03:00
parent 6b1a837f69
commit b1a9bad9e7
7 changed files with 279 additions and 1 deletions
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16
src/backend/catalog/system_views.sql
View File

@ -662,6 +662,22 @@ CREATE VIEW pg_stat_replication AS
WHERE S.usesysid = U.oid AND
S.pid = W.pid;
CREATE VIEW pg_stat_wal_receiver AS
SELECT
s.pid,
s.status,
s.receive_start_lsn,
s.receive_start_tli,
s.received_lsn,
s.received_tli,
s.last_msg_send_time,
s.last_msg_receipt_time,
s.latest_end_lsn,
s.latest_end_time,
s.slot_name
FROM pg_stat_get_wal_receiver() s
WHERE s.pid IS NOT NULL;
CREATE VIEW pg_stat_ssl AS
SELECT
S.pid,

154
src/backend/replication/walreceiver.c
View File

@ -46,9 +46,12 @@
#include <signal.h>
#include <unistd.h>
#include "access/htup_details.h"
#include "access/timeline.h"
#include "access/transam.h"
#include "access/xlog_internal.h"
#include "catalog/pg_type.h"
#include "funcapi.h"
#include "libpq/pqformat.h"
#include "libpq/pqsignal.h"
#include "miscadmin.h"
@ -57,7 +60,9 @@
#include "storage/ipc.h"
#include "storage/pmsignal.h"
#include "storage/procarray.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/pg_lsn.h"
#include "utils/ps_status.h"
#include "utils/resowner.h"
#include "utils/timestamp.h"
@ -1215,3 +1220,152 @@ ProcessWalSndrMessage(XLogRecPtr walEnd, TimestampTz sendTime)
pfree(receipttime);
}
}
/*
* Return a string constant representing the state. This is used
* in system functions and views, and should *not* be translated.
*/
static const char *
WalRcvGetStateString(WalRcvState state)
{
switch (state)
{
case WALRCV_STOPPED:
return "stopped";
case WALRCV_STARTING:
return "starting";
case WALRCV_STREAMING:
return "streaming";
case WALRCV_WAITING:
return "waiting";
case WALRCV_RESTARTING:
return "restarting";
case WALRCV_STOPPING:
return "stopping";
}
return "UNKNOWN";
}
/*
* Returns activity of WAL receiver, including pid, state and xlog locations
* received from the WAL sender of another server.
*/
Datum
pg_stat_get_wal_receiver(PG_FUNCTION_ARGS)
{
#define PG_STAT_GET_WAL_RECEIVER_COLS 11
TupleDesc tupdesc;
Datum values[PG_STAT_GET_WAL_RECEIVER_COLS];
bool nulls[PG_STAT_GET_WAL_RECEIVER_COLS];
WalRcvData *walrcv = WalRcv;
WalRcvState state;
XLogRecPtr receive_start_lsn;
TimeLineID receive_start_tli;
XLogRecPtr received_lsn;
TimeLineID received_tli;
TimestampTz last_send_time;
TimestampTz last_receipt_time;
XLogRecPtr latest_end_lsn;
TimestampTz latest_end_time;
char *slotname;
/* No WAL receiver, just return a tuple with NULL values */
if (walrcv->pid == 0)
PG_RETURN_NULL();
/* 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(PG_STAT_GET_WAL_RECEIVER_COLS, false);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "pid",
INT4OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "status",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 3, "receive_start_lsn",
LSNOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 4, "receive_start_tli",
INT4OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 5, "received_lsn",
LSNOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 6, "received_tli",
INT4OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 7, "last_msg_send_time",
TIMESTAMPTZOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 8, "last_msg_receipt_time",
TIMESTAMPTZOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 9, "latest_end_lsn",
LSNOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 10, "latest_end_time",
TIMESTAMPTZOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 11, "slot_name",
TEXTOID, -1, 0);
BlessTupleDesc(tupdesc);
/* Take a lock to ensure value consistency */
SpinLockAcquire(&walrcv->mutex);
state = walrcv->walRcvState;
receive_start_lsn = walrcv->receiveStart;
receive_start_tli = walrcv->receiveStartTLI;
received_lsn = walrcv->receivedUpto;
received_tli = walrcv->receivedTLI;
last_send_time = walrcv->lastMsgSendTime;
last_receipt_time = walrcv->lastMsgReceiptTime;
latest_end_lsn = walrcv->latestWalEnd;
latest_end_time = walrcv->latestWalEndTime;
slotname = pstrdup(walrcv->slotname);
SpinLockRelease(&walrcv->mutex);
/* Fetch values */
values[0] = Int32GetDatum(walrcv->pid);
if (!superuser())
{
/*
* Only superusers can see details. Other users only get the pid
* value to know whether it is a WAL receiver, but no details.
*/
MemSet(&nulls[1], true, PG_STAT_GET_WAL_RECEIVER_COLS - 1);
}
else
{
values[1] = CStringGetTextDatum(WalRcvGetStateString(state));
if (XLogRecPtrIsInvalid(receive_start_lsn))
nulls[2] = true;
else
values[2] = LSNGetDatum(receive_start_lsn);
values[3] = Int32GetDatum(receive_start_tli);
if (XLogRecPtrIsInvalid(received_lsn))
nulls[4] = true;
else
values[4] = LSNGetDatum(received_lsn);
values[5] = Int32GetDatum(received_tli);
if (last_send_time == 0)
nulls[6] = true;
else
values[6] = TimestampTzGetDatum(last_send_time);
if (last_receipt_time == 0)
nulls[7] = true;
else
values[7] = TimestampTzGetDatum(last_receipt_time);
if (XLogRecPtrIsInvalid(latest_end_lsn))
nulls[8] = true;
else
values[8] = LSNGetDatum(latest_end_lsn);
if (latest_end_time == 0)
nulls[9] = true;
else
values[9] = TimestampTzGetDatum(latest_end_time);
if (*slotname == '\0')
nulls[10] = true;
else
values[10] = CStringGetTextDatum(slotname);
}
/* Returns the record as Datum */
PG_RETURN_DATUM(HeapTupleGetDatum(
heap_form_tuple(tupdesc, values, nulls)));
}

2
src/include/catalog/catversion.h
View File

@ -53,6 +53,6 @@
*/
/* yyyymmddN */
#define CATALOG_VERSION_NO 201601052
#define CATALOG_VERSION_NO 201601071
#endif

2
src/include/catalog/pg_proc.h
View File

@ -2787,6 +2787,8 @@ DATA(insert OID = 2022 ( pg_stat_get_activity PGNSP PGUID 12 1 100 0 0 f f f
DESCR("statistics: information about currently active backends");
DATA(insert OID = 3099 ( pg_stat_get_wal_senders PGNSP PGUID 12 1 10 0 0 f f f f f t s r 0 0 2249 "" "{23,25,3220,3220,3220,3220,23,25}" "{o,o,o,o,o,o,o,o}" "{pid,state,sent_location,write_location,flush_location,replay_location,sync_priority,sync_state}" _null_ _null_ pg_stat_get_wal_senders _null_ _null_ _null_ ));
DESCR("statistics: information about currently active replication");
DATA(insert OID = 3317 ( pg_stat_get_wal_receiver PGNSP PGUID 12 1 0 0 0 f f f f f f s r 0 0 2249 "" "{23,25,3220,23,3220,23,1184,1184,3220,1184,25}" "{o,o,o,o,o,o,o,o,o,o,o}" "{pid,status,receive_start_lsn,receive_start_tli,received_lsn,received_tli,last_msg_send_time,last_msg_receipt_time,latest_end_lsn,latest_end_time,slot_name}" _null_ _null_ pg_stat_get_wal_receiver _null_ _null_ _null_ ));
DESCR("statistics: information about WAL receiver");
DATA(insert OID = 2026 ( pg_backend_pid PGNSP PGUID 12 1 0 0 0 f f f f t f s r 0 0 23 "" _null_ _null_ _null_ _null_ _null_ pg_backend_pid _null_ _null_ _null_ ));
DESCR("statistics: current backend PID");
DATA(insert OID = 1937 ( pg_stat_get_backend_pid PGNSP PGUID 12 1 0 0 0 f f f f t f s r 1 0 23 "23" _null_ _null_ _null_ _null_ _null_ pg_stat_get_backend_pid _null_ _null_ _null_ ));

2
src/include/replication/walreceiver.h
View File

@ -14,6 +14,7 @@
#include "access/xlog.h"
#include "access/xlogdefs.h"
#include "fmgr.h"
#include "storage/latch.h"
#include "storage/spin.h"
#include "pgtime.h"
@ -148,6 +149,7 @@ extern PGDLLIMPORT walrcv_disconnect_type walrcv_disconnect;
/* prototypes for functions in walreceiver.c */
extern void WalReceiverMain(void) pg_attribute_noreturn();
extern Datum pg_stat_get_wal_receiver(PG_FUNCTION_ARGS);
/* prototypes for functions in walreceiverfuncs.c */
extern Size WalRcvShmemSize(void);

13
src/test/regress/expected/rules.out
View File

@ -1848,6 +1848,19 @@ pg_stat_user_tables| SELECT pg_stat_all_tables.relid,
pg_stat_all_tables.autoanalyze_count
FROM pg_stat_all_tables
WHERE ((pg_stat_all_tables.schemaname <> ALL (ARRAY['pg_catalog'::name, 'information_schema'::name])) AND (pg_stat_all_tables.schemaname !~ '^pg_toast'::text));
pg_stat_wal_receiver| SELECT s.pid,
s.status,
s.receive_start_lsn,
s.receive_start_tli,
s.received_lsn,
s.received_tli,
s.last_msg_send_time,
s.last_msg_receipt_time,
s.latest_end_lsn,
s.latest_end_time,
s.slot_name
FROM pg_stat_get_wal_receiver() s(pid, status, receive_start_lsn, receive_start_tli, received_lsn, received_tli, last_msg_send_time, last_msg_receipt_time, latest_end_lsn, latest_end_time, slot_name)
WHERE (s.pid IS NOT NULL);
pg_stat_xact_all_tables| SELECT c.oid AS relid,
n.nspname AS schemaname,
c.relname,