| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Dimitri Fontaine <dfontaine(at)hi-media(dot)com>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, David Fetter <david(at)fetter(dot)org>, Bruce Momjian <bruce(at)momjian(dot)us>, fazool mein <fazoolmein(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Synchronous replication - patch status inquiry |
| Date: | 2010-09-07 15:23:43 |
| Message-ID: | 1283873023.1834.15272.camel@ebony |
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| Lists: | pgsql-hackers |
On Tue, 2010-09-07 at 10:47 -0400, Tom Lane wrote:
> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> > On Tue, 2010-09-07 at 09:27 +0300, Heikki Linnakangas wrote:
> >> For the sake of argument, yes that's what I was thinking. Now please
> >> explain how *you're* thinking it should work.
>
> > The WAL is sent from master to standby in 8192 byte chunks, frequently
> > including multiple commits. From standby, one reply per chunk. If we
> > need to wait for apply while nothing else is received, we do.
>
> That premise is completely false. SR does not send WAL in page units.
> If it did, it would have the same performance problems as the old
> WAL-file-at-a-time implementation, just with slightly smaller
> granularity.
There's no dependence on pages in that proposal, so don't understand.
What aspect of the above would you change? and to what?
--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Training and Services
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