Re: shared_buffers advice

Tom Lane escribió:
> Alvaro Herrera <alvherre@commandprompt.com> writes:
> > Maybe it would make more sense to try to reorder the fsync calls
> > instead.
>
> Reorder to what, though?  You still have the problem that we don't know
> much about the physical layout on-disk.

Well, to block numbers as a first step.

However, this reminds me that sometimes we take the block-at-a-time
extension policy too seriously.  We had a customer that had a
performance problem because they were inserting lots of data to TOAST
tables, causing very frequent extensions.  I kept wondering whether an
allocation policy that allocated several new blocks at a time could be
useful (but I didn't try it).  This would also alleviate fragmentation,
thus helping the physical layout be more similar to logical block
numbers.

--
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support