On 27 March 2015 at 04:54, Kyotaro HORIGUCHI
<horiguchi.kyotaro@lab.ntt.co.jp> wrote:
> Hello,
>
> At Thu, 26 Mar 2015 18:50:24 +0100, Andres Freund <andres@2ndquadrant.com> wrote in
<20150326175024.GJ451@alap3.anarazel.de>
>> I think the problem here is that the *primary* makes no such
>> assumptions. Init forks are logged via stuff like
>> smgrwrite(index->rd_smgr, INIT_FORKNUM, BTREE_METAPAGE,
> ..
>> i.e. the data is written out directly to disk, circumventing
>> shared_buffers. It's pretty bad that we don't do the same on the
>> standby. For master I think we should just add a bit to the XLOG_FPI
>> record saying the data should be forced out to disk. I'm less sure
>> what's to be done in the back branches. Flushing every HEAP_NEWPAGE
>> record isn't really an option.
>
> The problem exists only for INIT_FORKNUM. So I suppose it is
> enough to check forknum to decide whether to sync immediately.
>
> Specifically for this instance, syncing buffers of INIT_FORKNUM
> at the end of XLOG_FPI block in xlog_redo fixed the problem.
>
> The another (ugly!) solution sould be syncing only buffers for
> INIT_FORKNUM and is BM_DIRTY in ResetUnlogggedRelations(op =
> UNLOGGED_RELATION_INIT). This is catching-all-at-once solution
> though it is a kind of reversion of fast promotion. But buffers
> to be synced here should be pretty few.
This bug still exists.
Thom
