Message-ID: <4A0C7F96.2040407@enterprisedb.com>
Date: Thu, 14 May 2009 23:31:18 +0300
From: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Organization: EnterpriseDB
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To: Simon Riggs <simon@2ndQuadrant.com>
CC: Fujii Masao <masao.fujii@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>,
	Guillaume Smet <guillaume.smet@gmail.com>,
	Peter Eisentraut <peter_e@gmx.net>,
	Kevin Grittner <Kevin.Grittner@wicourts.gov>,
	pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: New trigger option of pg_standby
References: <3f0b79eb0903242329j12865d55s348f5c873a956e71@mail.gmail.com>	
	<49F01D79.8020805@enterprisedb.com>	
	<3f0b79eb0904230515p751b5248n6ef96880617db055@mail.gmail.com>	
	<4A095A39.3030100@enterprisedb.com>	
	<3f0b79eb0905130127u3a3275b1w79f4d8cb729ded36@mail.gmail.com>	
	<4A0A86D2.9080602@enterprisedb.com>
	<1985.1242234105@sss.pgh.pa.us>	
	<4A0B10C7.2040309@enterprisedb.com>	
	<1242247404.3843.503.camel@ebony.2ndQuadrant>	
	<1242315415.3843.526.camel@ebony.2ndQuadrant>	
	<3f0b79eb0905141149lf5cef92j538f490c86dfedf8@mail.gmail.com>
	<1242328204.3843.599.camel@ebony.2ndQuadrant>
In-Reply-To: <1242328204.3843.599.camel@ebony.2ndQuadrant>
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I've finally committed Simon's recovery_end_command patch, as well as 
the changes to pg_standby. There's now smart and fast failover modes, 
chosen by the content of the trigger file, smart mode is the default. A 
"fast" trigger file is truncated, turning it into a "smart" trigger for 
subsequent pg_standby invocations. I believe this is now safe in all the 
  combinations discussed, in both fast and smart mode, with or without 
extra WAL files copied to pg_xlog, and also if the last archived WAL 
file is incomplete.

You now need to set up recovery_end_command to clean up the trigger 
file; pg_standby no longer does that automatically.

Simon Riggs wrote:
> On Fri, 2009-05-15 at 03:49 +0900, Fujii Masao wrote:
>> Hi,
>>
>> On Fri, May 15, 2009 at 12:36 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
>>> On Wed, 2009-05-13 at 21:43 +0100, Simon Riggs wrote:
>>>> On Wed, 2009-05-13 at 21:26 +0300, Heikki Linnakangas wrote:
>>>>
>>>>> This whole thing can be considered to be a new feature.
>>>> recovery.conf will contain a new optional parameter:
>>>>
>>>> recovery_end_command (string)
>>> Implemented.
>>> + 		ereport(signaled ? FATAL : WARNING,
>>> + 				(errmsg("recovery_end_command \"%s\": return code %d",
>>> + 								xlogRecoveryEndCmd, rc)));
>> In fast failover case, pg_standby has to delete the trigger file immediately
>> if it's found. Otherwise, recovery may go wrong as I already described.
>> http://archives.postgresql.org/pgsql-hackers/2009-04/msg01139.php
>>
>> So, in fast mode, recovery_end_command would always fail to delete the
>> trigger file, and cause warning. This is odd behavior, I think. We should
>> change WARNING to DEBUG2 like RestoreArchivedFile() in the above code?
> 
> Using rm -f would avoid the WARNING.
> 
> I'd rather keep it at WARNING, since not sure what command I'll be
> running and what a non-zero rc means.
> 


-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com