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On Mon, 2007-10-22 at 13:53 +0800, K J wrote:<BR>
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<FONT COLOR="#000000">In our case, not really. It really depends on your current caching codebase. The only problem is the (current) lack of a consistent hashing algorithm [1] but YMMV. </FONT>
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<FONT COLOR="#000000">What is the consistent hashing part and why is it a bad thing?</FONT>
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The wiki explains the issue pretty well:<BR>
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<A HREF="http://www.socialtext.net/memcached/index.cgi?faq#how_does_memcached_handle_failover">http://www.socialtext.net/memcached/index.cgi?faq#how_does_memcached_handle_failover</A><BR>
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"With default clients <B>adding or removing</B> servers will invalidate all of your cache! Since the list of servers to hash against has changed, most of your keys will likely hash to different servers. It's like restarting all of your nodes at the same time."<BR>
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With a consistent hashing algorithm, node removal will not invalidate your cache, causing much less of an issue should you need to remove a node from the server pool.<BR>
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Hope that helps,<BR>
Rob.
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<B><FONT SIZE="2"><FONT COLOR="#333333">Rob Sharp</FONT></FONT></B><BR>
<FONT SIZE="1"><FONT COLOR="#ce4a84">Development Lead </FONT></FONT><BR>
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<B><FONT SIZE="1">telephone:</FONT></B><FONT SIZE="1"> 02 9282 4038</FONT><BR>
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<FONT SIZE="2"><FONT COLOR="#333333">Sound Alliance </FONT></FONT><BR>
<FONT SIZE="1"><FONT COLOR="#ce4a84">inthemix : FasterLouder : Thought By Them : SameSame</FONT></FONT>
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<FONT SIZE="1">"Poor workers blame their tools. Good workers build better tools. The best workers get their tools to do the work for them." -- Syndicate Wars</FONT><BR>
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