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Re: Snapshot synchronization, again...

From: Joachim Wieland <joe(at)mcknight(dot)de>
To: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Snapshot synchronization, again...
Date: 2010-12-31 14:38:51
Message-ID: AANLkTiktRBU5M6=Zgfmodn=ZX5VkZm=K2+_TdLxhYkC0@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Fri, Dec 31, 2010 at 8:28 AM, Alvaro Herrera
<alvherre(at)commandprompt(dot)com> wrote:
> A backend can have any number of snapshots registered, and those don't
> allow GlobalXmin to advance.  Consider an open cursor, for example.
> Even if the rest of the transaction is read committed, the snapshot
> registered by the open cursor still holds back GlobalXmin.  My
> (handwavy) idea is that whenever the transaction calls
> pg_publish_snapshot(), said snapshot is registered, which makes it safe
> to use even if the transaction continues to operate and obtain newer
> snapshots.

Cool, even better that this is taken care of already :-)

Thanks,
Joachim

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