[email protected] ("Kevin Grittner") writes: > Filip Rembia*kowski<[email protected]> wrote: >> 2011/1/19 Charles.Hou <[email protected]>: > >>> " select * from mybook" SQL command also increase the XID ? >> >> Yes. Single SELECT is a transaction. Hence, it needs a transaction >> ID. > > No, not in recent versions of PostgreSQL. There's virtual > transaction ID, too; which is all that's needed unless the > transaction writes something. > > Also, as a fine point, if you use explicit database transactions > (with BEGIN or START TRANSACTION) then you normally get one XID for > the entire transaction, unless you use SAVEPOINTs.
Erm, "not *necessarily* in recent versions of PostgreSQL." A read-only transaction won't consume XIDs, but if you don't expressly declare it read-only, they're still liable to get eaten... -- (format nil "~S@~S" "cbbrowne" "gmail.com") http://www3.sympatico.ca/cbbrowne/lisp.html Parenthesize to avoid ambiguity. -- Sent via pgsql-performance mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
