Redis: new disk storage to replace VM

Re:Redis: new disk storage to replace VM by snissn on Tuesday January 04, 2011 @05:49PM (#2068892)

sounds like he's trying to implement something similar to a 'dbm' (tokyo/kyoto as current/modern implementations) which are k/v caches that seem to intelligently write to disk.

Presumably the keyset can still be in ram (so that [star]foo[star]bar[star]1 searches on keys can work?), but the dbm model is a fairly efficient key/val implementation, and tokyo/kyoto is fast, and fairly smart about writing to disk, although I haven't explicitly testing their limitations as you approach ram limits in production.

Not sure what tradeoffs are in mind, but atleast a feature/perf comparison to kyoto compared with diskstore as an internal back for redis would be interesting

[1](doesnt seem i can escape an *)

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Re:Redis: new disk storage to replace VM by pashields on Tuesday January 04, 2011 @07:06PM (#2069173)

I don't think the keyset will be in ram: "Redis will never use more RAM, even if we have 2 MB of max memory and 1 billion of keys. This works since now we don't need to take keys in memory."

I haven't looked at the current code to see if there is a way to favor keeping the keys in memory, but it would seem that wildcard searches here can/will be disk-bound.

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Re:Redis: new disk storage to replace VM by snissn on Tuesday January 04, 2011 @07:22PM (#2069218)

tokyo supports a b-tree index on the keys written to disk which would optimize blah* queries but not [wildcard]foo[wildcard], and then writes become log(N)

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