| From: | Greg Smith <greg(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Stephen Frost <sfrost(at)snowman(dot)net> |
| Cc: | Andres Freund <andres(at)2ndquadrant(dot)com>, Peter Eisentraut <peter_e(at)gmx(dot)net>, Robert Haas <robertmhaas(at)gmail(dot)com>, Jon Nelson <jnelson+pgsql(at)jamponi(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: fallocate / posix_fallocate for new WAL file creation (etc...) |
| Date: | 2013-05-30 13:29:24 |
| Message-ID: | 51A75434.80609@2ndQuadrant.com |
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| Thread: | |
| Lists: | pgsql-hackers |
On 5/30/13 8:50 AM, Stephen Frost wrote:
> I don't think this solves the locking issue around the
> relation extention lock, but it might help some and it may make it
> easier to tweak that logic to allocate larger chunks in the future.
It might make it a bit faster, but it doesn't make it any easier to
implement. The messy part of extending relations in larger chunks is
how to communicate that back into the buffer manager usefully. The
extension path causing trouble is RelationGetBufferForTuple calling
ReadBufferBI. All of that is passing a single buffer around. There's
no simple way I can see to rewrite it to handle more than one at a time.
I have a test case for relation extension that I'm going to package up
soon. That makes it easy to see where the problem is at. Far as I can
tell the reason it hasn't been fixed before now is that it's a pain to
write the code.
--
Greg Smith 2ndQuadrant US greg(at)2ndQuadrant(dot)com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com
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