Durumdara wrote: > Please send me an example (pseudo-code) for Serializable conflict. > And I wanna know, if possible, that if more transactions only > read the tables in Serializable mode, and one or others write > to it, can I got some conflicts in read operation?
You get a serialization conflict if you try to modify a row in a serializable transaction T1 that has been changed by a second transaction T2 after T1 started. Sample 1: T1: START TRANSACTION ISOLATION LEVEL SERIALIZABLE; T1: SELECT * FROM t; id | val ----+------ 1 | test (1 row) T2: DELETE FROM t WHERE id=1; T1: UPDATE t SET val='new' WHERE id=1; ERROR: could not serialize access due to concurrent update Sample 2: T1: START TRANSACTION ISOLATION LEVEL SERIALIZABLE; T1: SELECT * FROM t; id | val ----+------ 1 | test (1 row) T2: UPDATE t SET val=val WHERE id=1; T1: DELETE FROM t; ERROR: could not serialize access due to concurrent update Yours, Laurenz Albe -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
