- autovacuum is not off in the pre-snapshot (production) database. It auto-runs every 2 weeks to avoid transaction ID wraparound. - I tried modifying pgdump to have a more relaxed transaction isolation (READ UNCOMMITTED) instead of the default (serializable) but this didn't help. thanks for the info.
On 10 December 2013 21:13, Jeff Janes <jeff.ja...@gmail.com> wrote: > On Tue, Dec 10, 2013 at 12:43 AM, Spiros Ioannou <siv...@inaccess.com>wrote: > >> Hi Jeff, >> autovacuum is off on the DB running on the filesystem snapshot. >> > > > Which probably makes sense on the snapshot, but is it also off on the > pre-snapshot database? > > >> What "hint bits" do you suppose it is setting? It's running only one COPY >> command for days. Do you have any suggestions to make it more "read only" ? >> > > > When a query sees a tuple that is still listed as part of an open > transaction, it needs to figure out whether that transaction has now > completed, and if so whether it committed or aborted. This can be quite a > bit of work to do, so once complete it sets a hint bit locally to that > tuple, so that the next visitor doesn't have to repeat the work. I don't > believe that there is any way to turn this off, unless you want to run your > own custom build of PostgreSQL. > > Cheers, > > Jeff >
