On Tue, Oct 11, 2011 at 1:11 PM, Simon Riggs <si...@2ndquadrant.com> wrote: > On Mon, Oct 10, 2011 at 11:31 PM, Kevin Grittner > <kevin.gritt...@wicourts.gov> wrote: >> Simon Riggs <si...@2ndquadrant.com> wrote: >> >>> How do we turn it on/off to allow the overhead to be measured? >> >> User REPEATABLE READ transactions or SERIALIZABLE transactions. The >> easiest way, if you're doing it for all transactions (which I >> recommend) is to set default_transaction_isolation. > > Most apps use mixed mode serializable/repeatable read and therefore > can't be changed by simple parameter. Rewriting the application isn't > a sensible solution. > > I think it's clear that SSI should have had and still needs an "off > switch" for cases that cause performance problems.
Is it possible that you are confusing the default level, which is READ COMMITTED, with REPEATABLE READ? I can't see why anyone would code up their application to use REPEATABLE READ for some things and SERIALIZABLE for other things unless they were explicitly trying to turn SSI off for a subset of their transactions. In all releases prior to 9.0, REPEATABLE READ and SERIALIZABLE behaved identically, so there wouldn't be any reason for a legacy app to mix-and-match between the two. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
