Re: Lock problem with autovacuum truncating heap

On 3/27/2011 10:43 PM, Tom Lane wrote:

> In particular, I thought the direction Jan was headed was to release and
> reacquire the lock between truncating off limited-size chunks of the
> file.  If we do that, we probably *don't* want or need to allow autovac
> to be booted off the lock more quickly.

That is correct.

>>  3) Scanning backwards 8MB at a time scanning each 8MB forwards instead
>>  of just going back by block backwards.
>
> Maybe.  I'd want to see some experimental evidence justifying the choice
> of chunk size; I'm pretty sure this will become counterproductive once
> the chunk size is too large.

Me too, which is why that part of my proposal is highly questionable and 
requires a lot of evidence to be even remotely considered for back releases.


Jan

-- 
Anyone who trades liberty for security deserves neither
liberty nor security. -- Benjamin Franklin