Re: Synchronization levels in SR - Mailing list pgsql-hackers

From Kevin Grittner
Subject Re: Synchronization levels in SR
Date
Msg-id 4BFD1B8F0200002500031B2F@gw.wicourts.gov
Whole thread Raw
In response to Re: Synchronization levels in SR  (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>)
List pgsql-hackers
Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> wrote:
>> Unless we have a transaction manager and do proper distributed
>> transactions, how do you avoid edge conditions like that?
> 
> Yeah, I guess you can't. You can guarantee that a commit is
> always safely flushed first in the master, or in the standby, but
> without two-phase commit you can't guarantee atomicity. It's
> useful to know which behavior you get, though, so that you can
> take it into account in your failover procedure.
It strikes me that if you always write the commit for the master
first, there's at least a possibility of developing a heuristic for
getting a slave back in sync should the connection break.  If you
randomly update zero to N slaves and then have a failure, I don't
see much hope.
-Kevin


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