From: | "Marc G(dot) Fournier" <scrappy(at)postgresql(dot)org> |
---|---|
To: | "Jeroen T(dot) Vermeulen" <jtv(at)xs4all(dot)nl> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Stupid question on Read Committed Isolation Level |
Date: | 2004-01-29 18:07:25 |
Message-ID: | 20040129140241.C6922@ganymede.hub.org |
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Lists: | pgsql-hackers |
On Thu, 29 Jan 2004, Jeroen T. Vermeulen wrote:
> On Thu, Jan 29, 2004 at 01:33:48PM -0400, Marc G. Fournier wrote:
>
> > What happens if I abort on the first transaction? If I'm reading this
>
> Doesn't matter, because your second transaction doesn't read any of the
> changes you're making there--until (and if) that first one commits. The
> second transaction simply doesn't care if the the first has been aborted
> or is still running. It would if the transaction level were READ
> UNCOMMITTED, but with postgres we don't need to worry about that.
Wait, did you read what I had originally posted? According to the docs
for what I read:
"If two such transactions concurrently try to change the balance of
account 12345, we clearly want the second transaction to start from the
updated version of the account's row"
To me, I read this as the first transaction has not yet committed, but the
second sees its changes ... so if second commitst, and first hasn't yet,
second commits with seconds changes + firsts changes, but what if first
aborts?
----
Marc G. Fournier Hub.Org Networking Services (http://www.hub.org)
Email: scrappy(at)hub(dot)org Yahoo!: yscrappy ICQ: 7615664
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