Re: [hibernate-dev] [infinispan-dev] Continuous Query Caching

On Sep 29, 2009, at 12:08 PM, Manik Surtani wrote: > > On 29 Sep 2009, at 09:57, Mircea Markus wrote: > >> Hi, >> >> Again, this is a feature from Coherence[1]. >> >> Basic idea is to execute a query against the cache, and hold the >> result object. This result object will always have up to date >> query result; this means that whenever something is modified in >> the cache the result itself is updated. Advantage: if one performs >> the same query very often(e.g. several times every millisecond) >> the response will be fast and the system will not be overloaded. > > Is it really faster? Surely all you save is the construction of > the various query objects, but the query itself would have to be re- > run every time. Or does it attach a listener to the cache and > check whether any new additions/removals should be used to update > the result set? this is the way it works. It is a sort of a near-cache, just that instead of being invalidated it is updated whenever the cache is updated. The documentation also suggests that they are using listeners. > I don't see how that could be much faster though. I think it might be if the you are running *the same query* tons of times. Basically you don't do a map-reduce on all the nodes, but rather on every insertion (especially if the number of insertion is relative small compared to the number of same-query-bring-run) you updated (if necessary) the cached query result.