Re: Allow "snapshot too old" error, to prevent bloat - Mailing list pgsql-hackers

From Kevin Grittner
Subject Re: Allow "snapshot too old" error, to prevent bloat
Date
Msg-id 1362088639.1929973.1424372075059.JavaMail.yahoo@mail.yahoo.com
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In response to Re: Allow "snapshot too old" error, to prevent bloat  (Rod Taylor <rod.taylor@gmail.com>)
Responses Re: Allow "snapshot too old" error, to prevent bloat
List pgsql-hackers
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.


Andrew's suggestion of setting this per table would not help here.


--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company



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