Re: purpose of thd_mark_transaction_to_rollback

Stewart Smith <[email protected]> Thu, 21 Jun 2012 14:35:02 +1000

Newsgroups	gmane.comp.db.mysql.devel
Message-ID	<[email protected]>

On Wed, 20 Jun 2012 13:22:50 -0400, Zardosht Kasheff <[email protected]> wrote:
> Thank you for your response. Why does InnoDB do this when a deadlock
> is detected? Does every storage engine need to do this? Is this part
> of some specification that calls for this? Or is it some sort of
> performance optimization?

Any storage engine that initiates rollback needs to call it. This
basically means any transactional engine, as there are situtions where
ROLLBACK is inevitable (e.g. ENOSPC if you're lucky enough to be able to
handle it).

It's not a performance optimization, it's about correctness. This is
telling the MySQL server that anybody else involved in the transaction
should now execute ROLLBACK as you've already done it. e.g. to ensure
that binlog doesn't contain operations that have been rolled back by
your engine.

-- 
Stewart Smith

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