-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 08/29/07 09:34, Decibel! wrote: > On Wed, Aug 29, 2007 at 08:37:26AM -0500, Ron Johnson wrote: >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> On 08/29/07 07:27, cluster wrote: >>> OK, thanks. But what with the second question in which the UPDATE is >>> based on a SELECT max(...) statement on another table? How can I ensure >>> that no other process inserts a row between my SELECT max() and UPDATE - >>> making my SELECT max() invalid? >>> >>> A table lock could be an option but I am only interested in blocking for >>> row insertions for this particular account_id. Insertions for other >>> account_ids will not make the SELECT max() invalid and should therefore >>> be allowed. >> Well, concurrency and transactional consistency *allows* other >> processes to update the table after you start your transaction. You >> just won't *see* their updates while you're inside of a transaction. > > Just make sure and read up about transaction isolation... in the default > of READ COMMITTED mode, you can sometimes see changes made by other > transactions. Argh!!! The RDBMS that I typically use defaults to SERIALIZABLE. - -- Ron Johnson, Jr. Jefferson LA USA Give a man a fish, and he eats for a day. Hit him with a fish, and he goes away for good! -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFG1YxuS9HxQb37XmcRAlJOAKCWL+NtM95YC2bMkFjOkD2NfF/xuQCggfKO QQC/mW+IYtlV6R9rqaSomMs= =H3+i -----END PGP SIGNATURE----- ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
