On Wed, Sep 20, 2017 at 4:25 AM, Michael Paquier <michael.paqu...@gmail.com> wrote: > On Wed, Sep 20, 2017 at 12:47 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: >> Amit Kapila <amit.kapil...@gmail.com> writes: >>> On Tue, Sep 19, 2017 at 9:27 AM, Michael Paquier >>> <michael.paqu...@gmail.com> wrote: >>>> I am not saying that no index AMs take advantage FPW compressibility >>>> for their meta pages. There are cases like this one, as well as one >>>> code path in BRIN where this is useful, and it is useful as well when >>>> logging FPWs of the init forks for unlogged relations. >> >>> Hmm, why is it useful for logging FPWs of the init forks for unlogged >>> relations? We don't use REGBUF_STANDARD in those cases. >> >> But if we started to do so, that would be a concrete benefit of this >> patch ... > > In the proposed set of patches, all the empty() routines part of index > AMs which use log_newpage_buffer() (brin, gin, spgst) are doing the > right thing by updating log_newpage_buffer(). btree also should have > its call to log_newpage updated in btbuildempty(), and your patch is > missing that. >
We can add that for btree patch. > Also, _hash_init() would need some extra work to > generate FPWs, but I don't think that it is necessary per its handling > of a per-record meta data either. So REGBUF_STANDARD could be just > removed from there, and there is actually no need to patch > src/backend/access/hash at all. > I think there is no need to remove it. As per discussion above, we want to keep REGBUF_STANDARD for all metapage initializations for the matter of consistency and that will be useful for wal_consistency_checking in which case we anyway need full page image. -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers