Hi all,
I have a high traffic database, where I'm interested in changing the
wal segment size to a larger value. I haven't found much
documentation about how to change the segment size of an existing
database. The obvious, safe solution would be to create a new
database cluster and dump/reload. This isn't ideal for a large
database though.
Pg_resetwal has a wal-segsize option, but the documentation doesn't
provide much guidance beyond that it's there. The pg_resetwal manpage
also has big warnings all over it about how the tool can corrupt your
database cluster. So my question is, is it safe to change wal-segsize
using pg_resetwal following a clean shutdown of the database? Just
reading the docs, it seems like the corruption issues are more around
non-graceful shutdowns or crash scenarios, with incomplete
transactions being wiped out by a wal reset. If the database was
shutdown cleanly this doesn't *seem* like it would be an issue.
Has anyone had experience doing this? I assume this would break any
physical replication standbys. Any other gotchas I should be looking
out for?
I've tested on a trivial (empty) database cluster, and everything
seems okay. But corruption might be difficult to detect until it's
too late.
Thanks,
James Lucas
