PostgreSQL 10 High Performance - Third Edition

checkpoint_segments – max_wal_size

In PostgreSQL 10, checkpoint_segments has been replaced with max_wal_size. Each WAL segment takes up 16 MB. As described at http://www.postgresql.org/docs/current/interactive/wal-configuration.html, the maximum number of WAL segments you can expect to be in use at any time is:

(2 + checkpoint_completion_target) * checkpoint_segments + 1  

On PostgreSQL 10, checkpoint_segments is approximately equivalent to max_wal_size/(3 * 16 MB) as seen in Chapter 5, Memory for Database Caching.

Note that in PostgreSQL versions before 8.3 that do not have spread checkpoints, you can still use this formula; just substitute the following code snippet for the value you'll be missing:

checkpoint_completion_target=0 

The easiest ...