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From: Greg Smith <greg@2ndQuadrant.com>
To: pgsql-admin@postgresql.org
Subject: Re: Problem with Streaming Replication
Date: Thu, 30 Jun 2011 11:05:38 -0400
Message-ID: <4E0C90C2.3000207@2ndQuadrant.com> (raw)
In-Reply-To: <1309436503938-4538638.post@n5.nabble.com>
References: <1309436503938-4538638.post@n5.nabble.com>

On 06/30/2011 08:21 AM, abraao895 wrote:
> - The HD of the PC1(master) dead. The WAL file don't have replicated because
> it is a asynchronous proccess and suppose that this already didn't have
> happened.
>
> - The PC2(slave) doesn't have the last record.
>    

That's exactly how some transaction loss can happen in this situation.  
Some software worried about this problem maintains a small transaction 
log outside of the database, so that it's possible to reconstruct really 
critical information after such a disaster.

In PostgreSQL 9.1, due to be released later this year, synchronous 
replication is available on a per-transaction basis.  That resolves the 
concern you have--important transactions can be confirmed on one of the 
slaves as a requirement before they commit.

-- 
Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
Comprehensive and Customized PostgreSQL Training Classes:
http://www.2ndquadrant.us/postgresql-training/




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