Re: First steps with 8.3 and autovacuum launcher

On Tue, Sep 18, 2007 at 06:51:04PM +0200, Guillaume Smet wrote:
> Hi all,
>
> As we will soon enter beta, I decided to give a try to 8.3devel. The
> first step is of course to load a dump from an existing database.
>
> The dump is a text dump of 1.6 GB (database is approximately 4 GB).
>
> The restore is far slower than with 8.2. From time to time ALTER TABLE
> queries creating primary keys are waiting for a long time. After a
> while, I discovered that that I had three autovacuum processes which
> were running to analyze the created tables while the dump was trying
> to create primary keys on these very tables.
>
> While I understand that it's important to have a fully analyzed
> database, I usually do it at the end of the restore and the fact that
> three tables are analyzed concurrently while primary keys are created
> is far from optimal IMHO as primary keys creation often (*really*
> often in my case) waits for autovacuum to finish its job.

Odd... I'd expect it to actually be beneficial to run analyze on a table
at roughly the same time as PK building, because you'd make better use
of cache. OTOH, unless something's changed, analyze should read at most
30k pages, which I wouldn't expect to take all that long...
--
Decibel!, aka Jim C. Nasby, Database Architect decibel(at)decibel(dot)org
Give your computer some brain candy! www.distributed.net Team #1828