Re: empty pg_stat_replication when replication works fine?

I've found the reason: inconsistent catalog data.
This state did not disappear after restart of all postgres instances.

pg_authid.oid does not match the one in pg_stat_get_activity(NULL::integer).

I wonder how this inconsistency could happen.. Maybe some error during
cloning database (binary database copy, or some older WAL logs left over
either in archive or pg_xlog, or some corrupted index in pg_catalog?)
during several test-cycles..

Any other idea how can oid of users could be different from the one
appearing in pg_stat_get_activity()? (see details below)

Andrej
--------------details:
postgres=# \d+ pg_stat_replication;
View "pg_catalog.pg_stat_replication"
Column | Type | Modifiers | Storage |
Description
------------------+--------------------------+-----------+----------+-------------
pid | integer | | plain |
usesysid | oid | | plain |
usename | name | | plain |
application_name | text | | extended |
client_addr | inet | | main |
client_hostname | text | | extended |
client_port | integer | | plain |
backend_start | timestamp with time zone | | plain |
state | text | | extended |
sent_location | text | | extended |
write_location | text | | extended |
flush_location | text | | extended |
replay_location | text | | extended |
sync_priority | integer | | plain |
sync_state | text | | extended |
View definition:
SELECT s.pid,
s.usesysid,
u.rolname AS usename,
s.application_name,
s.client_addr,
s.client_hostname,
s.client_port,
s.backend_start,
w.state,
w.sent_location,
w.write_location,
w.flush_location,
w.replay_location,
w.sync_priority,
w.sync_state
FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid,
application_name, state, query, waiting, xact_start, query_start,
backend_start, state_change, client_addr, client_hostname, client_port),
pg_authid u,
pg_stat_get_wal_senders() w(pid, state, sent_location, write_location,
flush_location, replay_location, sync_priority, sync_state)
WHERE s.usesysid = u.oid AND s.pid = w.pid;

postgres=# \dv+ pg_stat_replication;
List of relations
Schema | Name | Type | Owner | Size | Description
------------+---------------------+------+----------+---------+-------------
pg_catalog | pg_stat_replication | view | postgres | 0 bytes |
(1 row)

postgres=# select * from pg_stat_get_wal_senders();
pid | state | sent_location | write_location | flush_location |
replay_location | sync_priority | sync_state
-----+-----------+---------------+----------------+----------------+-----------------+---------------+------------
707 | streaming | 0/B5000090 | 0/B5000090 | 0/B5000090 |
0/B5000090 | 0 | async
(1 row)

postgres=# select * from pg_stat_get_activity(NULL::integer);
datid | pid | usesysid | application_name | state |
query | waiting | xact_start |
query_star
t | backend_start | state_change
| client_addr | client_hostname | client_port
-------+-----+----------+------------------+--------+----------------------------------------------------+---------+-------------------------------+--------------------
-----------+-------------------------------+-------------------------------+----------------+-----------------+-------------
0 | 707 | 34456 | l2amain | idle |
| f | |
| 2016-05-31 13:19:04.875468+02 | 2016-05-31 13:19:04.877894+02
| 192.168.101.11 | | 33329
12896 | 709 | 10 | psql | active | select * from
pg_stat_get_activity(NULL::integer); | f | 2016-05-31
13:22:23.090373+02 | 2016-05-31 13:22:23
.090373+02 | 2016-05-31 13:19:08.719215+02 | 2016-05-31 13:22:23.090382+02
| | | -1
(2 rows)

postgres=# select * from pg_authid where oid = 34456;
rolname | rolsuper | rolinherit | rolcreaterole | rolcreatedb |
rolcatupdate | rolcanlogin | rolreplication | rolconnlimit | rolpassword |
rolvaliduntil
---------+----------+------------+---------------+-------------+--------------+-------------+----------------+--------------+-------------+---------------
(0 rows)

postgres=# select oid, * from pg_authid;
oid | rolname | rolsuper | rolinherit | rolcreaterole | rolcreatedb |
rolcatupdate | rolcanlogin | rolreplication | rolconnlimit | rolpassword |
rolvaliduntil
-------+-----------+----------+------------+---------------+-------------+--------------+-------------+----------------+--------------+-------------+---------------
10 | postgres | t | t | t | t |
t | t | t | -1 | |
29732 | xxusrrole | f | t | f | f |
f | f | f | -1 | |
29733 | xxadmrole | f | t | f | f |
f | f | f | -1 | |
29734 | xxschema | f | t | f | f |
f | t | f | -1 | xxxxxxxx |
29735 | xxadm | f | t | f | f |
f | t | f | -1 | xxxxx |
29737 | pgbackup | f | t | f | f |
f | t | f | -1 | xxxxxxxx |
29738 | pgmonitor | f | t | f | f |
f | t | f | -1 | xxxxxxxxx |
29739 | pgreplic | f | t | f | f |
f | t | t | -1 | xxxxxxxx |
29736 | CTSYSTEM | f | t | f | f |
f | t | f | -1 | xxxxxx |
(9 rows)

2016-05-25 23:22 GMT+02:00 Andrej Vanek <andrej(dot)vanek(dot)sk(at)gmail(dot)com>:

> Streaming replication set-up,
>
> one master, 3 slaves connecting to it.
> I expected ps -ef gets all wal-sender processes and SAME information I'll
> get via select * from pg_stat_replication.
> Instead I observed:
> - pg_stat_replication is empty
> - 3 wal-sender processes up and running
> - each slave has wal-receiver process running
> - replication works (tried to create a table- it appears in all databases)
> Question:
> - why is pg_stat_replication empty?
>
> Andrej
> ---------------details
> [root(at)l2bmain ~]# tail /opt/pg_data/postgresql.conf
> max_wal_senders = 5
> hot_standby = on
> wal_keep_segments = 128
> archive_command = '/opt/postgres/dbconf/archive_command.sh %p %f'
> wal_receiver_status_interval = 2
> max_standby_streaming_delay = -1
> max_standby_archive_delay = -1
> restart_after_crash = off
> hot_standby_feedback = on
> wal_sender_timeout = 1min
> [root(at)l2bmain ~]# ps f -fu postgres
> UID PID PPID C STIME TTY STAT TIME CMD
> postgres 10797 1 0 15:53 ? S 0:20
> /usr/pgsql-9.3/bin/postgres -D /opt/pg_data -c
> config_file=/opt/pg_data//postgresql.conf
> postgres 10820 10797 0 15:53 ? Ss 0:00 \_ postgres: logger
> process
> postgres 10823 10797 0 15:53 ? Ss 0:00 \_ postgres:
> checkpointer process
> postgres 10824 10797 0 15:53 ? Ss 0:00 \_ postgres: writer
> process
> postgres 10825 10797 0 15:53 ? Ss 0:00 \_ postgres: wal
> writer process
> postgres 10826 10797 0 15:53 ? Ss 0:01 \_ postgres:
> autovacuum launcher process
> postgres 10827 10797 0 15:53 ? Ss 0:00 \_ postgres: archiver
> process last was 0000000100000000000000A3.00000028.backup
> postgres 10828 10797 0 15:53 ? Ss 0:03 \_ postgres: stats
> collector process
> postgres 11286 10797 0 15:54 ? Ss 0:08 \_ postgres: wal
> sender process pgreplic 192.168.204.12(55231) streaming 0/A401BED8
> postgres 11287 10797 0 15:54 ? Ss 0:06 \_ postgres: wal
> sender process pgreplic 192.168.204.11(42937) streaming 0/A401BED8
> postgres 19322 10797 0 15:58 ? Ss 0:08 \_ postgres: wal
> sender process pgreplic 192.168.101.11(52379) streaming 0/A401BED8
> postgres 28704 10797 0 18:44 ? Ss 0:00 \_ postgres: CTSYSTEM
> lidb 192.168.102.13(58245) idle
> postgres 7256 10797 0 18:52 ? Ss 0:00 \_ postgres: CTSYSTEM
> lidb 192.168.102.23(55190) idle
> postgres 8667 10797 0 18:53 ? Ss 0:00 \_ postgres: CTSYSTEM
> lidb 192.168.102.13(58287) idle
> [root(at)l2bmain ~]# psql -U postgres -c "select * from pg_stat_replication;"
> pid | usesysid | usename | application_name | client_addr |
> client_hostname | client_port | backend_start | state | sent_location |
> write_location | flush_location | r
> eplay_location | sync_priority | sync_state
>
> -----+----------+---------+------------------+-------------+-----------------+-------------+---------------+-------+---------------+----------------+----------------+--
> ---------------+---------------+------------
> (0 rows)
>
> [root(at)l2bmain ~]# tail /opt/pg_data/pg_log/postgresql-Wed.log
> 2016-05-25 15:53:56 CEST:@:[8603] LOG: database system is shut down
> 2016-05-25 15:53:58 CEST:@:[10821] LOG: database system was shut down in
> recovery at 2016-05-25 15:53:56 CEST
> 2016-05-25 15:53:58 CEST:@:[10821] LOG: database system was not properly
> shut down; automatic recovery in progress
> 2016-05-25 15:53:58 CEST:@:[10821] LOG: consistent recovery state
> reached at 0/A2000090
> 2016-05-25 15:53:58 CEST:@:[10821] LOG: record with zero length at
> 0/A2000090
> 2016-05-25 15:53:58 CEST:@:[10821] LOG: redo is not required
> 2016-05-25 15:53:58 CEST:@:[10821] LOG: MultiXact member wraparound
> protections are now enabled
> 2016-05-25 15:53:58 CEST:@:[10797] LOG: database system is ready to
> accept connections
> 2016-05-25 15:53:58 CEST:@:[10826] LOG: autovacuum launcher started
> `
> [root(at)l2bmain ~]# ssh 192.168.101.11
> Last login: Wed May 25 22:48:18 2016 from 192.168.101.12
> [root(at)l2amain ~]# ps f -fu postgres
> UID PID PPID C STIME TTY STAT TIME CMD
> postgres 5730 1 0 15:58 ? S 0:04
> /usr/pgsql-9.3/bin/postgres -D /opt/pg_data -c
> config_file=/opt/pg_data//postgresql.conf
> postgres 5754 5730 0 15:58 ? Ss 0:00 \_ postgres: logger
> process
> postgres 5755 5730 0 15:58 ? Ss 0:00 \_ postgres: startup
> process recovering 0000000100000000000000A4
> postgres 5773 5730 0 15:58 ? Ss 0:12 \_ postgres: wal
> receiver process streaming 0/A401C030
> postgres 5774 5730 0 15:58 ? Ss 0:00 \_ postgres:
> checkpointer process
> postgres 5775 5730 0 15:58 ? Ss 0:00 \_ postgres: writer
> process
> postgres 5776 5730 0 15:58 ? Ss 0:00 \_ postgres: stats
> collector process
> [root(at)l2amain ~]# psql -U postgres -c "select pg_is_in_recovery();"
> pg_is_in_recovery
> -------------------
> t
> (1 row)
> [root(at)l2bmain ~]# ssh 192.168.204.11
> Warning: Permanently added '192.168.204.11' (RSA) to the list of known
> hosts.
> Last login: Wed May 25 16:28:49 2016 from 192.168.200.254
> [root(at)l2abrnch ~]# ps f -fu postgres
> UID PID PPID C STIME TTY STAT TIME CMD
> postgres 8174 1 0 15:48 ? S 0:04
> /usr/pgsql-9.3/bin/postgres -D /opt/geo_stdby_data -c
> config_file=/opt/geo_stdby_data//postgresql.conf
> postgres 8195 8174 0 15:48 ? Ss 0:00 \_ postgres: logger
> process
> postgres 8197 8174 0 15:48 ? Ss 0:00 \_ postgres: startup
> process recovering 0000000100000000000000A4
> postgres 8206 8174 0 15:48 ? Ss 0:00 \_ postgres:
> checkpointer process
> postgres 8207 8174 0 15:48 ? Ss 0:00 \_ postgres: writer
> process
> postgres 8208 8174 0 15:48 ? Ss 0:00 \_ postgres: stats
> collector process
> postgres 11414 8174 0 15:53 ? Ss 0:13 \_ postgres: wal
> receiver process streaming 0/A401C0D0
>
> [root(at)l2bmain ~]# ssh 192.168.204.11
> Warning: Permanently added '192.168.204.11' (RSA) to the list of known
> hosts.
> Last login: Wed May 25 16:28:49 2016 from 192.168.200.254
> [root(at)l2abrnch ~]# ps f -fu postgres
> UID PID PPID C STIME TTY STAT TIME CMD
> postgres 8174 1 0 15:48 ? S 0:04
> /usr/pgsql-9.3/bin/postgres -D /opt/geo_stdby_data -c
> config_file=/opt/geo_stdby_data//postgresql.conf
> postgres 8195 8174 0 15:48 ? Ss 0:00 \_ postgres: logger
> process
> postgres 8197 8174 0 15:48 ? Ss 0:00 \_ postgres: startup
> process recovering 0000000100000000000000A4
> postgres 8206 8174 0 15:48 ? Ss 0:00 \_ postgres:
> checkpointer process
> postgres 8207 8174 0 15:48 ? Ss 0:00 \_ postgres: writer
> process
> postgres 8208 8174 0 15:48 ? Ss 0:00 \_ postgres: stats
> collector process
> postgres 11414 8174 0 15:53 ? Ss 0:13 \_ postgres: wal
> receiver process streaming 0/A401C0D0
> [root(at)l2abrnch ~]# psql -U postgres -c "select pg_is_in_recovery();"
> pg_is_in_recovery
> -------------------
> t
> (1 row)
>
> [root(at)l2abrnch ~]# logout
> Connection to 192.168.204.11 closed.
> [root(at)l2bmain ~]# ssh 192.168.204.12
> Warning: Permanently added '192.168.204.12' (RSA) to the list of known
> hosts.
> Last login: Wed May 25 14:58:03 2016 from 192.168.200.254
> [root(at)l2bbrnch ~]# ps f -fu postgres
> UID PID PPID C STIME TTY STAT TIME CMD
> postgres 22885 1 0 15:48 ? S 0:00
> /usr/pgsql-9.3/bin/postgres -D /opt/geo_stdby_data -c
> config_file=/opt/geo_stdby_data//postgresql.conf
> postgres 22913 22885 0 15:48 ? Ss 0:00 \_ postgres: logger
> process
> postgres 22914 22885 0 15:48 ? Ss 0:00 \_ postgres: startup
> process recovering 0000000100000000000000A4
> postgres 22917 22885 0 15:48 ? Ss 0:00 \_ postgres:
> checkpointer process
> postgres 22918 22885 0 15:48 ? Ss 0:00 \_ postgres: writer
> process
> postgres 22919 22885 0 15:48 ? Ss 0:00 \_ postgres: stats
> collector process
> postgres 26163 22885 0 15:54 ? Ss 0:13 \_ postgres: wal
> receiver process streaming 0/A401C0D0
>
>