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<div>Its good to know that some people find that it works. </div>
<div>How many tables are you replicating? (we have 415). </div>
<div>What is "busy" for you? (we have about 3 million operations a day on average). </div>
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<span style="font-weight:bold">From: </span>Tory M Blue <<a href="mailto:tmblue@gmail.com">tmblue@gmail.com</a>><br>
<span style="font-weight:bold">Date: </span>Thursday, November 29, 2012 11:39 AM<br>
<span style="font-weight:bold">To: </span>Frank McGeough <<a href="mailto:frank.mcgeough@vocalocity.com">frank.mcgeough@vocalocity.com</a>><br>
<span style="font-weight:bold">Cc: </span>"<a href="mailto:slony1-general@lists.slony.info">slony1-general@lists.slony.info</a>" <<a href="mailto:slony1-general@lists.slony.info">slony1-general@lists.slony.info</a>><br>
<span style="font-weight:bold">Subject: </span>Re: [Slony1-general] Slony version 2.1.0 switchover<br>
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<div class="gmail_quote">On Tue, Nov 27, 2012 at 8:59 AM, Frank McGeough <span dir="ltr">
<<a href="mailto:Frank.Mcgeough@vocalocity.com" target="_blank">Frank.Mcgeough@vocalocity.com</a>></span> wrote:<br>
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<div>I'm writing to ask about using Slony switchover capability. I've never actually been able to make this work. I'm curious about whether this is a common experience or if, perhaps, there is something that I don't understand about how this should function.
The environment that I have is a database that is in constant use. That is, there is always at least a low level of DML (inserts for the most part) occurring 24 x 7, 365 days a year. I've found that Slony will never be able to get a lock in order to perform
the switchover and thus I'm left with tearing replication completely down and rebuilding from scratch if I have to perform maintenance on the primary. Do people find this unusual or is this somewhat expected — and the only time this actually functions as described
in the documentation is if you are able to shutdown all database operations for a short period of time ( a few seconds even)? </div>
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<div>What I do currently is use a VIP ( <a href="http://en.wikipedia.org/wiki/Virtual_IP_address" target="_blank">
http://en.wikipedia.org/wiki/Virtual_IP_address</a> ) to control how the various app servers are connecting to the primary database. I modify this to go to what was the slave, stop the slony processes, drop the slony schema and then restart replication from
scratch. </div>
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Slony is designed to do exactly what you are stating it's not able to. We run a very busy site and switchover's "albeit one of those moments where you hold your breath", work without an issue (knocks on wood). We too use a virtual for our insert DB's and Query
db's (inserts are the master/slave) . As part of the switchover we hit the switchover button (script) and at about the same time, we move the slave into the vip. We have 3 sets that have to move, but 99.9% of the time the switchover works without a hitch (the
.1% is when we have done changes, or schema modifications or other and didn't clean up after ourselves properly).<br>
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So this works and has worked for many many versions now.<br>
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Not sure why it can't get a lock, at some point it's request has to take priority over a later request.<br>
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Tory<br>
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