Hello David, I replied to your original e-mail but it must have vanished into the ether. I sent you a brief precis about transaction processing. For "SELECT FOR UPDATE" to function, you MUST have an unique key on the table. For example:- crawlq_id SERIAL NOT NULL PRIMARY KEY USING INDEX TABLESPACE xyz, That creates a sequence and whenever you insert a row into the table, it automatically grabs the next value and stores it in that column. Without knowing exactly what or how your application functions, I made a suggestion that I believe will save you some grief. Create a new table crawlq_processed (say) and your transaction flow becomes:- BEGIN; SELECT row FOR UPDATE; Supplying the unique key and row is now locked. Do your processing. INSERT INTO crawlq_processed; DELETE FROM crawlq; COMMIT; or ROLLBACK; if errors occurred. All of the above in appropriate try . . catch blocks. You need to set up a cron job to vacuum table crawlq. The SELECT FOR UPDATE will not stop other processes inserting or reading from crawlq. You have just locked a single row thus "protecting" it from being updated or deleted by another process. HTH. Cheers, Robert -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
