On Wed, Mar 15, 2017 at 10:34 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: > FWIW, I'm not certain that Stephen is correct to claim that we have > some concrete problem with sparse files. We certainly don't *depend* > on sparse storage anyplace else, nor write data in a way that would be > likely to trigger it; but I'm not aware that we need to work hard to > avoid it.
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. If we do care about failures due to deferred allocation, then leaving holes in the file is a bad idea. -- 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
