Re: Allow "snapshot too old" error, to prevent bloat

On 2/19/15 1:54 PM, Kevin Grittner wrote:
> Rod Taylor <rod.taylor@gmail.com> wrote:
>
>> Would pg_dump be able to opt-out of such a restriction?
>
> I don't see how, since vacuum would be removing recently dead
> tuples that are still visible; the alternative to getting a
> "snapshot too old" error when reading a page which could be
> affected is to return incorrect results, and nobody wants that.
> The best you could do if you wanted to run pg_dump (or similar) and
> it might take more time than your old_snapshot_threshold would be
> to increase the threshold, reload, dump, set it back to the
> "normal" setting, and reload again.

While I think pg_dump is a great solution for small to medium
installations, there are a number of excellent file-based backup options
available.  Anyone who is seriously worried about bloat (or locking)
should be looking to those solutions.

--
- David Steele
david@pgmasters.net