On Wed, Apr 22, 2009 at 2:58 PM, Heikki Linnakangas
<heikki.linnakangas@enterprisedb.com> wrote:
> Tom Lane wrote:
>>
>> Does a prepared xact still block vacuum cleanup in HEAD, or has that
>> been fixed since 8.2?
>
> It still does. A prepared xact is just like a idle-in-transaction backend as
> far as vacuum is concerned.
Is that really necessary? It's true that you can't vacuum away any
rows whose xmin is that of the prepared xact, but it seems like you
wouldn't need to keep rows just because they were *visible* to the
prepared xact. Once prepared, it's no longer capable of reading them.
...Robert