is bigger really better, when it comes to memcached?
josh at agliodbs.com
Thu Jun 28 07:10:18 UTC 2007
> On the other hand, lets say you have a users table with 50 columns. You do
> a select * from users where user_id = 1. But instead of caching the entire
> result as a serialized object in memcache, you break the result set into 5
> memcache objects, with 10 column attributes in each. When you want to fetch
> the cache for that user, you now are doing a multiget for 5 memcache
> objects or if you only need part of the user's data, you fetch less of it.
> But when only an attribute in one of the cache objects is updated, only
> that cache object needs to be expired.
Me, I'd intelligently separate the frequently from the infrequently updated
columns, not just in memcached but in the tables as well. In fact, I've done
this for several applications. Then I go even further and only synch some
frequently updated information periodically (say, every minute) so that the
DB isn't getting hit with dozens of transitory updates. If it's something
like a last_pageview time, you can really afford to lose a few seconds if it
cuts your database I/O by 20x.
PostgreSQL @ Sun
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