RE: Problem of pg_wal filling up

From: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>

Dear Experts,

Post the setup of streaming replication –MASTER and one SLAVE in PostgreSQL 12 , the pg_wal in both MASTER/SLAVE are - filling up.

Do you have any replication slots on the replica? When you created the replica, you were supposed to exclude the directory pg_replslot. If you didn't the replica might have "inherited" slots it should not have.

* No I haven’t created any replication slots on the replica, but its keep filling the logs in pg_wal? So does it mean it can go anywhere without a slot?

My MASTER is in archive log mode and SLAVE in no archive log mode.

MASTER

postgres=# show archive_command;
archive_command
------------------------------------------------------------------------------------
test ! -f /data/tablespaces/archivedir/%f && cp %p /data/tablespaces/archivedir/%f

Is this command succeeding? Do you see messages in the log file about it failing? Are new files showing up in '/data/tablespaces/archivedir/'?

Does the master have any old replication slots which have been abandoned or are falling behind? Check the view pg_replication_slots.

Is it advisable to change default wal location (pg_wal)? Or any other options apart from using pg_archivecleanup?

pg_archivecleanup is for cleaning up the archive (which is apparently '/data/tablespaces/archivedir/'). It is *not* for cleaning up pg_wal.

Cheers,

Jeff