On 29 July 2011 14:01, Ken Wesson <kwess...@gmail.com> wrote: > On Fri, Jul 29, 2011 at 7:41 AM, László Török <ltoro...@gmail.com> wrote: >> Hi, >> >> is there a way to execute multiple select queries on a table using clojureql >> in a transaction? >> >> sg. like >> >> (with-results [res1 query1 >> res2 query2] >> .. do sg) >> >> and res1 and res2 would be taken from a same consistent snapshot. > > If you run two separate queries, I expect the database server will see > them as two separate transactions, and may interleave some other, > mutating transaction between them, so they won't in that case be taken > from a consistent snapshot.
Well, I suppose it you use SELECT FOR UPDATE/SHARE it should not allow changes between them, but I've never used SELECT FOR UPDATE or SHARE, so perhaps I'm wrong or I'm misunderstanding your point. e.g. http://www.postgresql.org/docs/9.0/static/sql-select.html#SQL-FOR-UPDATE-SHARE http://dev.mysql.com/doc/refman/5.0/en/innodb-locking-reads.html So, I think this should work: BEGIN; SELECT ... FOR SHARE; SELECT ...; COMMIT; Whether it's possible to do that with ClojureQL I have no idea. > You'd need to have a single query to the DB, which will run as a > single transaction, generate both res1 and res2. I'm not sure if that > will always be possible; my SQL-fu is a little rusty. -- Michael Wood <esiot...@gmail.com> -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
