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<br><div><div>On Jul 3, 2007, at 21:03 , Ben Manes wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: 'times new roman'; font-size: 16px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; ">I'm using the standard Java client which, like most clients, supports auto-failover support. I don't quite understand how this works since my understanding is that the server (bucket) is chosen by hashing the keys and modding by the server list. It also doesn't seem like dynamically updating the server list is supported, which other threads have touched on. Could someone explain the built-in failover support and how robust it is?<br></span></blockquote></div><div><br class="webkit-block-placeholder"></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>There are two commonly employed strategies:<br class="webkit-block-placeholder"></div><div><br class="webkit-block-placeholder"></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>1) Since the server is chosen by computing a hash of the key modulus the number of servers, you must maintain a consistent ordering of servers on each client's list, so you can just walk the list when a server fails.<br class="webkit-block-placeholder"></div><div><br class="webkit-block-placeholder"></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>2) Using a yet-to-be-completely-standardized consistent hashing mechanism.<br class="webkit-block-placeholder"></div><div><br></div><div><br class="webkit-block-placeholder"></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>Either way, it's up to the client, so as long as you're not trying to read and write data built using different clients, it really doesn't matter which strategy your client employs as long as you've proven it works for you.</div><div><br class="webkit-block-placeholder"></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>Consistent hashing is conceptually a little more complicated, but causes less stress on your data source when you're growing or shrinking your clusters.<br class="webkit-block-placeholder"></div><br><div> <span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div>-- </div><div>Dustin Sallings</div><br class="Apple-interchange-newline"></span> </div><br></body></html>