Horton

Re: Standalone synchronous master

Andres Freund <andres@2ndquadrant.com>

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From: Andres Freund <andres@2ndquadrant.com>
To: "Joshua D. Drake" <jd@commandprompt.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Kevin Grittner <kgrittn@ymail.com>, Bruce Momjian <bruce@momjian.us>, Heikki Linnakangas <hlinnakangas@vmware.com>, Simon Riggs <simon@2ndQuadrant.com>, Rajeev rastogi <rajeev.rastogi@huawei.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2014-01-08T23:04:38Z
Lists: pgsql-hackers 
On 2014-01-08 14:52:07 -0800, Joshua D. Drake wrote:
> On 01/08/2014 02:46 PM, Andres Freund wrote:
> >>The idea is that we know that data on db0 is not written until we know for a
> >>fact that db1 also has that data. That is great and a guarantee of data
> >>integrity between the two nodes.
> >
> >That guarantee is never there. The only thing guaranteed is that the
> >client isn't notified of the commit until db1 has received the data.
> 
> Well ugh on that.. but that is for another reply.

You do realize that locally you have the same guarantees? If the client
didn't receive a reply to a COMMIT you won't know whether the tx
committed or not. If that's not sufficient you need to use 2pc and a
transaction manager.

Greetings,

Andres Freund

-- 
 Andres Freund	                   http://www.2ndQuadrant.com/
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