PECL memcache extension
timo at tzc.com
Tue Feb 7 06:29:14 UTC 2006
Paul G wrote:
> ----- Original Message ----- From: "Don MacAskill" <don at smugmug.com>
> To: "memcached mail list" <memcached at lists.danga.com>
> Cc: <mikl at php.net>
> Sent: Friday, February 03, 2006 5:37 PM
> Subject: PECL memcache extension
> -- snip --
>> If "set key1" is destined to ServerB's buckets, but ServerB fails, I
>> don't want "key1" being redirected to ServerA instead. Why? Because
>> when ServerB comes online, I now have "key1" in two places, and one
>> of them will now potentially get out of date. Should ServerB fail
>> again before "key1" has expired, calls to "get key1" will return old
>> stale data from ServerA instead of fresh data or no result.
>> Make sense? Am I doing something wrong? Can the PECL extension work
>> in this fashion?
> maybe i'm missing something, but i don't think the case you're trying
> to protect against is actually going to occur. once serverB comes back
> online (and gets added to the rotation, which gets rehashed), all
> further queries for key1 will again be run against it, whether it's
> set or get. sure, you get a stale entry for it on serverA, but if it
> never gets queried for it again, who cares?
You don't care if all goes well, but if serverB fails again, it will
drop back to serverA again, which still has stale data which it is
perfectly happy to serve as if it was not stale.
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