Re: WAL Archive Cleanup?

Hello All,

Ok, so maybe something helpful?  On my master node I am seeing a bunch of:

2019-03-28 23:54:44 GMT [2611]: [1-1] user=admin,db=admin,client=17210.10.37 172.10.10.37(57552) (0:3D000)FATAL:  database "admin" does not exist

2019-03-28 23:54:46 GMT [2613]: [1-1] user=admin,db=admin,client=172.10.10.18 172.10.10.18(56970) (0:3D000)FATAL:  database "admin" does not exist

Which is accurate, as there is no admin database...  I usually connect with 

psql -h localhost -U admin postgres

Should there be?  Will this fix my issue with pgsql filling up the disk?

Thanks,

- QBR

On Mon, Mar 25, 2019 at 10:21 AM Foo Bar <qubitrenegade@gmail.com> wrote:

Hello All,

Wow!  Lots of awesome replies, Went away for the weekend thinking my email had been rejected and come back to a full inbox.  Thanks for all the help!

>> Postgres version?

9.6.11

Doh.  Fairly important detail there.  :)

>> FYI, psql is the Postgres client program, Postgres(ql) is the server.

>> "psql" is the name of a specific command line tool used to connect to a PostgreSQL database server, it is not the name of the database itself. The database is usually abbreviated "pgsql".

Duly noted, thanks for the correction.

>> It's the standby that has not seen any traffic?

There's really no traffic.  I built three nodes, connected them, created a test table and inserted some values, then left the cluster be for a couple weeks.

>>  And "restartpoint" is usually spelled as one work in technical discussions of it.  Or at least, searching for it that way avoids finding things which mention each word separately in different senses.

Ah ha.  I had seen it that way but thought it was a typo.  Thanks for the clarification!

>> Are you sure it is the archive directory (/hab/svc/postgresql/data/archive) which is filling up, and not the live directory (pg_wal or pg_xlog)?  This is often a point of confusion.

Right before I sent the mail last week I deleted everything in /hab/svc/postgresql/data/archive, this morning I'm seeing:

# du -h --max=1 /hab/svc/postgresql/data/

198M /hab/svc/postgresql/data/pgdata

8.9G /hab/svc/postgresql/data/archive

9.1G /hab/svc/postgresql/data/

# du -hs /hab/svc/postgresql/data/pgdata/pg_xlog/

177M /hab/svc/postgresql/data/pgdata/pg_xlog/

# ls -lah /hab/svc/postgresql/data/archive/ | wc -l

571

There is no pg_wal directory though (should there be?)

# find /hab/svc/postgresql/ -name '*pg*wal*'

#

>>  If the only reason you want an archive is for replication, then use streaming replication and do away with the archive completely

To be honest, I thought it was required for streaming replication based on the guides linked above.

>> There are reasons other than replication that one might want to keep a WAL archive, but those reasons don't seem to apply to you

Like backup maybe?  A wholly other topic, we recently had a power outage and I lost a pgsql node... having an archive would allow me to "replay" any transactions?

>> What needs to be determined here is why the standby never consumed the WAL's from the master?

Ok, so it the standby that's the problem.

>> Do you still have the logs from the standby and do they show anything relevant?

Sure, what am I looking for?  I see a bunch of entries like:

2019-03-08 17:06:11 GMT [1813]: [815-1] user=,db=,client=  (0:00000)LOG:  restartpoint complete: wrote 22 buffers (0.0%); 0 transaction log file(s) added, 0 removed, 1 recycled; write=2.211 s, sync=0.062 s, total=2.281 s; sync files=18, longest=0.062 s, average=0.003 s; distance=16383 kB, estimate=16383 kB

2019-03-08 17:06:11 GMT [1813]: [816-1] user=,db=,client=  (0:00000)LOG:  recovery restart point at 0/8D000028

On the 15th, around when I think I filled the disk, I see a bunch of:

cp: cannot stat '/00000002.history': No such file or directory

cp: cannot stat '/000000010000000400000049': No such file or directory

2019-03-15 23:59:49 GMT [16691]: [1-1] user=,db=,client=  (0:XX000)FATAL:  could not connect to the primary server: could not connect to server: Connection refused

                Is the server running on host "172.16.10.23" and accepting

                TCP/IP connections on port 5432?

Which makes sense since the pgsql service was down.

This appears to be when I recovered the master on Thursday:

cp: cannot stat '/00000002.history': No such file or directory

cp: cannot stat '/00000001000000040000004D': No such file or directory

2019-03-21 17:37:31 GMT [31338]: [1-1] user=,db=,client=  (0:XX000)FATAL:  could not connect to the primary server: could not connect to server: Connection refused

                Is the server running on host "172.16.10.23" and accepting

                TCP/IP connections on port 5432?

cp: cannot stat '/00000002.history': No such file or directory

cp: cannot stat '/00000001000000040000004D': No such file or directory

2019-03-21 17:37:36 GMT [31343]: [1-1] user=,db=,client=  (0:00000)LOG:  started streaming WAL from primary at 4/4D000000 on timeline 1

2019-03-21 17:37:47 GMT [30711]: [3151-1] user=,db=,client=  (0:00000)LOG:  restartpoint starting: time

2019-03-21 17:37:47 GMT [30711]: [3152-1] user=,db=,client=  (0:00000)LOG:  restartpoint complete: wrote 0 buffers (0.0%); 0 transaction log file(s) added, 0 removed, 1 recycled; write=0.003 s, sync=0.000 s, total=0.007 s; sync files=0, longest=0.000 s, average=0.000 s; distance=16384 kB, estimate=16384 kB

Then there's a bunch of the same entries where about the only thing (other than the timestamp) that seems to change is the index in:

2019-03-23 23:33:40 GMT [30711]: [5094-1] user=,db=,client=  (0:00000)LOG:  recovery restart point at 5/90000140

2019-03-23 23:38:40 GMT [30711]: [5097-1] user=,db=,client=  (0:00000)LOG:  recovery restart point at 5/91000028

2019-03-23 23:43:40 GMT [30711]: [5100-1] user=,db=,client=  (0:00000)LOG:  recovery restart point at 5/91000108

I see effectively the same logs on the other hotstandby pgsql node.

This is my config on my standby node:

listen_addresses = '0.0.0.0'

port = 5432

max_connections = 100

external_pid_file = '/hab/svc/postgresql/var/postgresql.pid'

authentication_timeout = 1min

max_files_per_process = 1000

max_locks_per_transaction = 64

logging_collector = on

log_directory = '/hab/svc/postgresql/var/pg_log'

log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log'

log_line_prefix = '%t [%p]: [%l-1] user=%u,db=%d,client=%h %r (%x:%e)'

log_min_messages = ERROR

datestyle = 'iso, mdy'

default_text_search_config = 'pg_catalog.english'

data_directory = '/hab/svc/postgresql/data/pgdata'

hba_file = '/hab/svc/postgresql/config/pg_hba.conf'

wal_level = hot_standby

wal_log_hints = 'on'

hot_standby = 'on'

hot_standby_feedback = true

max_wal_senders = 5

max_replication_slots = 5

checkpoint_completion_target = 0.9

max_wal_size = 1GB

min_wal_size = 128MB

wal_keep_segments = 8

log_checkpoints = on

log_lock_waits = on

log_temp_files = 0

log_autovacuum_min_duration = 0

track_activity_query_size = 2048

track_io_timing=on

dynamic_shared_memory_type = 'none'

archive_mode = 'on'

archive_command = 'cp %p  /hab/svc/postgresql/data/archive/%f'

archive_timeout = '10min'

max_standby_archive_delay = '30s'

synchronous_commit = local

include '/hab/svc/postgresql/config/postgresql.local.conf'

Should I disable archive mode?  Even though I'm not currently using it, it seems like there's a use-case for having it?  And if I can configure out what causing the backup of archive files it should still be manageable?

Thanks again for all the replies, while it hasn't solved the problem yet, this was incredibly helpful!  Also, please don't hate me for munging all your replies into one reply...  I thought it might be easier to follow than having three different branches...?

Best Regards,

- QBR

On Fri, Mar 22, 2019 at 7:14 PM Michael Paquier <michael@paquier.xyz> wrote:

On Fri, Mar 22, 2019 at 12:26:33PM -0400, Jeff Janes wrote:
> archive_cleanup_command is pretty much obsolete.  The modern way to do this
> is with streaming replication, using either replication slots or
> wal_keep_segments.  If the only reason you want an archive is for
> replication, then use streaming replication and do away with the archive
> completely.  There are reasons other than replication that one might want
> to keep a WAL archive, but those reasons don't seem to apply to you.  And
> if they did you almost certainly wouldn't want to run
> archive_cleanup_command on it.

Personally, I still find archives also very valuable when a standby
creation takes a long time because of a large initial base backup and
that the partition dedicated to pg_wal is not large enough to support
the retention associated with a slot, and it is easier to have larger
retention policies in the archives.
--
Michael