Re: Serializable isolation level

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От Richard Huxton
Тема Re: Serializable isolation level
Дата
Msg-id 4354EB58.6020607@archonet.com
обсуждение исходный текст
Ответ на Serializable isolation level  (<sknipe@tucows.com>)
Ответы Re: Serializable isolation level  (Tom Lane <tgl@sss.pgh.pa.us>)
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sknipe@tucows.com wrote:
>
> I need you expert opinions on the following statement.

You have four statements here.

> The primary reason I use serialized transactions is to avoid race
> conditions.

Difficult to say why _you_ use them - they certainly can help there.
Make sure you read the bit on "true serializability" though.

 > One of postgresql's famed features is the MVCC
> (multi-version concurrency control) aka serialized transactions

Umm - no. MVCC underlies how all the transaction levels are implemented,
though you could implement them via other methods.

> which allows you to avoid using row/table level locks.

MVCC is designed to.

 > It's *supposed* to keep things moving much more
> quickly than locks allow for.

It allows reads to proceed without waiting for writes (with the
understanding that what you read may now be out of date).

Does that help at all?
--
   Richard Huxton
   Archonet Ltd

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