From: Andrew Dunstan <andrew@dunslane.net>
To: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: Simon Riggs <simon@2ndQuadrant.com>
Cc: pgsql-hackers@postgresql.org
Subject: Re: Re: [COMMITTERS] pgsql: Efficient transaction-controlled synchronous replication.
Date: Mon, 07 Mar 2011 08:30:34 -0500
Message-ID: <4D74DDFA.70800@dunslane.net> (raw)
In-Reply-To: <4D74896C.5030402@enterprisedb.com>
References: <E1PwMns-00047O-UU@gemulon.postgresql.org>
<4D741441.2090704@dunslane.net>
<1299454125.1696.6138.camel@ebony>
<4D74896C.5030402@enterprisedb.com>
On 03/07/2011 02:29 AM, Heikki Linnakangas wrote:
> On 07.03.2011 01:28, Simon Riggs wrote:
>> On Sun, 2011-03-06 at 18:09 -0500, Andrew Dunstan wrote:
>>>
>>> On 03/06/2011 05:51 PM, Simon Riggs wrote:
>>>> Efficient transaction-controlled synchronous replication.
>>>
>>> I'm glad this is in, but I thought we agreed NOT to call it
>>> "synchronous
>>> replication".
>>
>> The discussion on the thread was that its not sync rep unless we have
>> the strictest guarantees. We have the strictest guarantees, so it
>> qualifies as sync rep.
>
> What do you mean by "strictes guarantees"?
>
> I don't see allow_synchronous_standby setting in the committed patch.
> I presume you didn't make allow_synchronous_standby=off the default
> behavior. Also, the documentation that describes this as two-safe
> replication and claims that "the only possibility that data can be
> lost is if both the primary and the standby suffer crashes at the same
> time" needs big fat caveats to clarify that this doesn't actually
> achieve those guarantees.
>
> Please change the name.
>
Previously, Simon said:
> Truly "synchronous" requires two-phase commit, which this never was.
So I too am confused about how it's now become "truly synchronous". Are
we saying this give the same or better guarantees than a 2PC setup?
cheers
andrew
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To: pgsql-hackers@postgresql.org
Cc: andrew@dunslane.net, heikki.linnakangas@enterprisedb.com, simon@2ndQuadrant.com
Subject: Re: Re: [COMMITTERS] pgsql: Efficient transaction-controlled synchronous replication.
In-Reply-To: <4D74DDFA.70800@dunslane.net>
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