Re: [HACKERS] subscription worker signalling wal writer too much

On Mon, Jul 3, 2017 at 11:26 PM, Jeff Janes <jeff.janes@gmail.com> wrote:
> My understanding is that you can't start on a new file until the old file is
> completely synced, because the book keeping can currently only handle one
> file at a time.  So if you signal the wal writer to do the sync, you would
> just end up immediately blocking on it to finish.  Getting around that would
> require substantially more changes; we would need to implement a queue of
> full log files not yet synced so that we could move on without waiting.

Yeah.  I bet that effort would be reasonably worthwhile.  I believe
that the forced end-of-segment syncs are costing us a noticeable
amount of performance.  Once or twice I took a very half-hearted run
at doing what you describe here, but gave up pretty quickly; it seems
like a somewhat tricky problem.

-- 
Robert Haas
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