On Wed, Oct 12, 2011 at 6:34 AM, Heikki Linnakangas <heikki.linnakan...@enterprisedb.com> wrote: > On 11.10.2011 23:21, Simon Riggs wrote: >> >> If the normal default_transaction_isolation = read committed and all >> transactions that require serializable are explicitly marked in the >> application then there is no way to turn off SSI without altering the >> application. That is not acceptable, since it causes changes in >> application behaviour and possibly also performance issues. > > I don't get that. If all the transactions that require serializability are > marked as such, why would you disable SSI for them? That would just break > the application, since the transactions would no longer be serializable. > > If they don't actually need serializability, but repeatable read is enough, > then mark them that way.
Obviously, if apps require serializability then turning serializability off would break them. That is not what I have said, nor clearly not what I would mean by "turning off SSI". The type of serializability we had in the past is now the same as repeatable read. So the request is for a parameter that changes a request for serializable into a request for repeatable read, so that applications are provided with exactly what they had before, in 9.0 and earlier. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers