Re: Proposal for CSN based snapshots - Mailing list pgsql-hackers

From Ants Aasma
Subject Re: Proposal for CSN based snapshots
Date
Msg-id CA+CSw_utvZdR1QZ318xcDAK5-S0ghAdzLJH0kGM5oX1Np7KVaw@mail.gmail.com
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In response to Re: Proposal for CSN based snapshots  (Greg Stark <stark@mit.edu>)
List pgsql-hackers
On Fri, Jun 7, 2013 at 3:47 PM, Greg Stark <stark@mit.edu> wrote:
> On Thu, Jun 6, 2013 at 11:42 PM, Ants Aasma <ants@cybertec.at> wrote:
>> To refresh your memory the basic idea is to change visibility
>> determination to be based on a commit sequence number (CSN for short)
>> - a 8 byte number incremented on every commit representing the total
>> ordering of commits
>
> I think we would just use the LSN of the commit record which is
> effectively the same but doesn't require a new counter.
> I don't think this changes anything though.

I briefly touched on that point in the Hot Standby section. This has
some consequences for locking in CommitTransaction, but otherwise LSN
is as good as any other monotonically increasing value.

Regards,
Ants Aasma
--
Cybertec Schönig & Schönig GmbH
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A-2700 Wiener Neustadt
Web: http://www.postgresql-support.de



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