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?

I don't see how that could be much faster though.

Adding Hibernate-dev in cc so that the HIbernate Search guys can comment too. > E.g. > Filter filter = new AndFilter(new EqualsFilter("getTrader", > traderid), > new EqualsFilter("getStatus", > Status.OPEN)); > ContinuousQueryCache cacheOpenTrades = new > ContinuousQueryCache(cache, filter); > > Iterator iter = cacheOpenTrades.entrySet().iterator(); //*this > entrySet call will be instant!* > > FOr a full list of scenario in which this can be used take a look > at [1]. > Shall we consider adding something similar? > > Cheers, > Mircea > > > [1] http://download.oracle.com/docs/cd/E14526_01/coh.350/e14509/continuousque... > _______________________________________________ > infinispan-dev mailing list > infinispan-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/infinispan-dev -- Manik Surtani manik(a)jboss.org Lead, Infinispan Lead, JBoss Cache http://www.infinispan.org http://www.jbosscache.org _______________________________________________ infinispan-dev mailing list infinispan-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/infinispan-dev

On 29 Sep 2009, at 10:19, Mircea Markus wrote: > > 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. Hmm.  It would be pretty use-case-specific.  It's hard to see how this _generally_ performs better, since you need to make sure you are aware of all changes happening all over the cluster to keep this result set up to date (REPL-style scalability bottleneck!) Cheers -- Manik Surtani manik(a)jboss.org Lead, Infinispan Lead, JBoss Cache http://www.infinispan.org http://www.jbosscache.org _______________________________________________ infinispan-dev mailing list infinispan-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/infinispan-dev

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. E.g. Filter filter = new AndFilter(new EqualsFilter("getTrader", traderid), new EqualsFilter("getStatus", Status.OPEN)); ContinuousQueryCache cacheOpenTrades = new ContinuousQueryCache(cache, filter); Iterator iter = cacheOpenTrades.entrySet().iterator(); //*this entrySet call will be instant!* FOr a full list of scenario in which this can be used take a look at [1]. Shall we consider adding something similar?

Cheers, Mircea [1] http://download.oracle.com/docs/cd/E14526_01/coh.350/e14509/continuousque... _______________________________________________ infinispan-dev mailing list infinispan-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/infinispan-dev