Re: Postgresql the right tool (queue using advisory_locks + long transactions)

On 4/27/2014 2:07 PM, Hannes Erven wrote:
> On 2014-04-27 21:53, Tom Lane wrote:
> >
>> Sitting on an open transaction for hours would be a bad idea.
>
> I'm wondering why this is and what the consequences might be - I
> thought, the MVCC model would handle that rather well?
>
> Could please someone elaborate on this or provide some pointer? Thanks!

vacuum can't free up any tuples older than the oldest transaction in the
database.  also, indexes need to index all versions of a tuple that
could still be in use    in a heavy update environment, this could lead
to quite a lot of database bloat.

--
john r pierce                                      37N 122W
somewhere on the middle of the left coast