Re: a vacuum thread is not the answer

From: Jan Wieck <janwieck(at)yahoo(dot)com>
To: mlw <markw(at)mohawksoft(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: a vacuum thread is not the answer
Date: 2002-03-07 21:16:16
Message-ID: 200203072116.g27LGGw25082@saturn.janwieck.net
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mlw wrote:
> I was just toying around with things, and you know, running vacuum in the
> background doesn't work. It slows things down too much.
>
> The worst case senario is when one does this:
>
> update accounts set abalance = abalance + 1 ;
>
> This takes forever to run and doubles the size of the table.
>
> Is there a way that a separate thread managing the freelist can perform a "per
> row" vacuum concurrently? Maybe I am stating the problem incorrectly, but we
> need to be able to recover rows already in memory for performance.

So you want to reuse space from rows before your transaction
committed? Fine, I'm all for it, as long as

begin ;
update accounts set abalance = abalance + 1 ;
rollback ;

still works.

Jan

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