Re: Reliable and fast money transaction design

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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.

Of course, if you truly want exclusive access, you could LOCK the
table. It's well explained in the documentation...

- --
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!

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