On Wed, Mar 15, 2017 at 11:02 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> That theory seems inconsistent with how mdextend() works. My >> understanding is that we zero-fill the new blocks before populating >> them with actual data precisely to avoid running out of disk space due >> to deferred allocation at the OS level. If we don't care about >> failures due to deferred allocation at the OS level, we can rip that >> logic out and improve the performance of relation extension >> considerably. > > See my reply to Stephen. The fact that this fails to guarantee no > ENOSPC on COW filesystems doesn't mean that it's not worth doing on > other filesystems. We're reducing the risk, not eliminating it, > but reducing risk is still a worthwhile activity.
Well, then it would presumably be worth reducing for hash indexes, too. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
