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

[Manik Surtani]

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/continuousquery.htm#BABBEIAH
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--
Manik Surtani
manik at jboss.org
Lead, Infinispan
Lead, JBoss Cache
http://www.infinispan.org
http://www.jbosscache.org




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