Addendum to the FAQ

Hello,

based on a common question, here is an addendum for the FAQ:

Question: The files in pg_xlog/* take up a lot of disk space, can they be removed?

Answer:

Under no circumstances must files in the pg_xlog/ directory be removed, they are essential for the database operation. The files in this directory store the transaction log, without these files the database can't recover after a crash or shutdown.

The size of the pg_xlog/ directory can be configured by setting the "min_wal_size" and "max_wal_size" GUC (PostgreSQL 9.5 and newer), or by setting the "checkpoint_segments" GUC (9.4 and earlier).
https://www.postgresql.org/docs/current/static/runtime-config-wal.html
https://www.postgresql.org/docs/9.4/static/runtime-config-wal.html

Regards,