From: Andrew Dunstan <andrew@dunslane.net>
To: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: Aidan Van Dyk <aidan@highrise.ca>
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 10:51:49 -0500
Message-ID: <4D74FF15.1070804@dunslane.net> (raw)
In-Reply-To: <4D74FDEC.5040406@enterprisedb.com>
References: <E1PwMns-00047O-UU@gemulon.postgresql.org>
<4D741441.2090704@dunslane.net>
<1299454125.1696.6138.camel@ebony>
<4D74896C.5030402@enterprisedb.com>
<4D74DDFA.70800@dunslane.net>
<4D74E584.7080409@enterprisedb.com>
<4D74E9FA.7070202@dunslane.net>
<AANLkTinkzJ=UrLbThZy2KeQg+SjwYqj2r0mDomMwirB7@mail.gmail.com>
<4D74F3AE.9000802@dunslane.net>
<4D74FDEC.5040406@enterprisedb.com>
On 03/07/2011 10:46 AM, Heikki Linnakangas wrote:
> On 07.03.2011 17:03, Andrew Dunstan wrote:
>> This is about expectations. The thing that worries me is that the use of
>> this term might cause some people NOT to use 2PC because they think they
>> are getting an equivalent guarantee, when in fact they are not. And
>> that's hardly unreasonable. Here for example is what wikipedia says
>> <http://en.wikipedia.org/wiki/Replication_%28computer_science%29;:
>>
>> Synchronous replication - guarantees "zero data loss" by the means
>> of atomic write operation, i.e. write either completes on both sides
>> or not at all. Write is not considered complete until
>> acknowledgement by both local and remote storage.
>
> Hmm, I've read that wikipedia definition before, but the "atomic" part
> never caught my eye. You do get zero data loss with what we have; if a
> meteor strikes the master, no acknowledged transaction is lost. I find
> that definition a bit confusing.
Maybe it is - I agree the difference might be small. I'm just trying to
make sure we don't use a term that could mislead reasonable people about
what we're providing. If we're satisfied that we aren't, then keep it.
cheers
andrew
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To: pgsql-hackers@postgresql.org
Cc: andrew@dunslane.net, heikki.linnakangas@enterprisedb.com, aidan@highrise.ca, simon@2ndquadrant.com
Subject: Re: Re: [COMMITTERS] pgsql: Efficient transaction-controlled synchronous replication.
In-Reply-To: <4D74FF15.1070804@dunslane.net>
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