Comments on: A rant about proper memcache usage

By: Bartek

Bartek — Mon, 24 Aug 2009 10:40:29 +0000

Number of arguments vary – this is a huge app with hundreds of business logic methods (and business layer is cached in the way described). Sometimes arguments are array of values. I cannot put that into key name as plain text – I need to make an unique hash somehow.

I do not delete cache entries and don’t need to understand what particular key stands for. Cache entries have short expire of 60 seconds and that’s enough in terms of deletion. All I am concerned of is performance = how much I could gain riping off md5 and what to chose instead. Thanks

By: Joped

Joped — Fri, 21 Aug 2009 18:40:22 +0000

Depending on the number of arguments you are passing, you might want to consider listing out each parameter manually in the key name. For example: mykey_$sort_$order_$limit_$value1_$value2_$other

Its also much easier to perform a delete against a key like that in another part of your code. Unless you have a method for every key you create, which is kinda overboard.

Not to mention, it would also be much harder to understand what user_c4ca4238a0b923820dcc509a6f75849b is vs user_c81e728d9d4c2f636f067f89cc14862c when looking at memcached -vv or other debug tools.

It takes a little more work, but its all about key organization.

By: Bartek

Bartek — Fri, 21 Aug 2009 14:55:16 +0000

Good points. Instead one: I still use md5 for keys. Would love to read what you suggest instead.

My keys need to include method name + arguments passed, so I am using something like:
md5( serialize( array( method name, array( arguments passed ) ) ) ) as memcache key.

This keeps my keys unique and short (as serialized arguments might be longish sometimes). What would you suggest instead of md5 in that case?

By: 451 CAOS Theory » The commercialisation of Memcached

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By: Chris Henry

Chris Henry — Sat, 06 Jun 2009 19:06:26 +0000

This is a really great post on memcache best practices. It’s pretty much everything I’ve learned the hard way, particularly connecting using the external IP. That finer point will actually be causing me some pain later this month…

By: Bryn

Bryn — Fri, 13 Mar 2009 21:41:35 +0000

Spot on Joe. Good article! Now it you’ll excuse me, I need to go get a .22 for that spider…