David,
This setting is the indirect means to ensure that the WAL directory
doesn't get too large by forcing a checkpoint thus allowing the
corresponding WAL to be removed.
This is a soft limit, ok.
But the question is a little different.
Suppose we have: version >= 11, no replication slots, archive_mode =
off.
Checkpoint_timeout is big enough, so checkpoints triggered only by
max_wal_size (1GB).
checkpoint_completion_target = 1.
What size of WAL files will be generated between checkpoints?
1GB or 0.5GB?
As I understand the description of max_wal_size(Maximum size to let the
WAL grow to between automatic WAL checkpoints), the answer is 1GB.
But it seems that the right answer is 0.5GB.
-----
Pavel Luzanov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
