Re: Read Lock For Foreign Key
От | Jon Swinth |
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Тема | Re: Read Lock For Foreign Key |
Дата | |
Msg-id | 200208131920.g7DJKIM02602@localhost.localdomain обсуждение исходный текст |
Ответ на | Re: Read Lock For Foreign Key (Jan Wieck <JanWieck@Yahoo.com>) |
Список | pgsql-general |
Thanks for your reply Jan. I fully understand that the difficulty is why is has not already been done. I was simply trying to take the first step in getting something done in a software project... getting it on the todo list. On Tuesday 13 August 2002 12:14 pm, Jan Wieck wrote: > Jon Swinth wrote: > > How come having foreign keys take out a read lock on a parent row rather > > than a write lock is not on the todo list? I had someone tell me that > > this is difficult because the SQL standard does not include syntax for > > read lock. Does the fact that it will be difficult mean that it isn't > > needed? > > The problem is that the row has to be locked against concurrent updates > until the end of the transaction. As of now, the only way to do that > under PostgreSQLs MVCC is to grab a lock FOR UPDATE, which is exclusive. > > The fact that it is difficult does not mean it isn't needed. It is > simply the reason why it hasn't been done yet. > > > Jan
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