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Date: Wed, 11 Jan 2012 13:50:48 -0800
From: Manoj Govindassamy <manoj@nimblestorage.com>
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To: <pgsql-general@postgresql.org>
Subject: PG synchronous replication and unresponsive slave
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Hi,

I have a PG 9.1.2 Master <--> Slave with synchronous replication setup. 
They are all working fine as expected. I do have a case where I want to 
flip Master to non replication mode whenever its slave is not 
responding. I have set replication_timeout to 5s and whenever salve is 
not responding for for more than 5s, i see the master detecting it. But, 
the transactions on the master is stuck till the slave comes back. To 
get over it, I reloaded the config on master with synchronous_commit = 
local. Further transactions on the master are going thru fine with this 
local commits turned on.

Here are my questions:

1. Transaction which was stuck right when slave going away never went 
thru even after I reloaded master's config with local commit on. I do 
see all new transactions on master are going thru fine, except the one 
which was stuck initially. How to get this stuck transaction complete or 
return with error.

2. Whenever there is a problem with slave, I have to manually reload 
master's config with local commit turned on to get master go forward. Is 
there any automated way to reload this config with local commit on on 
slave's unresponsiveness ? tcp connection timeouts, replication timeouts 
all detect the failures, but i want to run some corrective action on 
these failure detection.

-- 
thanks,
Manoj