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From "Ard Schrijvers" <a.schrijv...@hippo.nl>
Subject RE: Jackrabbit XPath performance
Date Thu, 08 Nov 2007 10:14:01 GMT
Hello Kisu,

> Kisu San wrote: 
> My Xpath query is
> //element(*, "BULLETIN")[jcr:deref(@btnmodel= 'MODEL_NAME') 
> and jcr:deref(@btnbulletin_type= 'INFO')]
> BULLETIN ==> Node type
> btnmodel = REFERENCE property in BULLETIN node 
> btnbulletin_type= REFERENCE property in BULLETIN node
> I have created 10,000 of the bulletin nodes, of which 1000 
> are matching to my search criteria. That means, returned 
> reasult set will have 1000 nodes.
> It is taking 319,012 milli seconds ~ 5.31 seconds on DB2  and 
> 246,157 milli seconds on Derby.
> Which is lot of time in my opinion. 

Yes, this is a lot of time. I haven't had yet time to look at jcr:deref
(DerefQuery), so I am not sure wether this query might be slow.
Currently, there are certain queries which might become slow, see for
example https://issues.apache.org/jira/browse/JCR-1196. 

But, as in your example, the time takes doesn't say to much, because it
is not clear wether the time taken is in the lucene query or in the
getResults. Obviously, the first part, the lucene query is independant
of your DB. Also, 300 ms - 5 sec is a big difference. But, you might
refer to 5 sec the very first time you search, where all caches are
empty, the lucene caches are empty, your FS cache is empty, the readers
are yet read, etc etc

So, I cannot do anything with the numbers you currently show. For 10.000
nodes, even the slowest queries should be (pretty) fast. So, I propose
you do the following:

1) Set the limit of results returned because you just shouldn't fetch
1000 nodes at once : you have something like:
Query q =

now, add ((QueryImpl)q).setLimit(1); 

2) Measure the time of the third (three times in row) 'result =
q.execute();' , not the first.

Now, change the ((QueryImpl)q).setLimit(1); to for example
((QueryImpl)q).setLimit(1000); and see the difference. Fetching 1000
nodes in QueryResultImpl.getResults(long size) will obviously, certainly
when you just started the repository like in a unittest which you
probably are doing, always be slower

Regards Ard

> Can any one tell me if there is anyway of improving performance??
> Thanks in Advance
> Kishore
> --
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> http://www.nabble.com/Jackrabbit-XPath-performance-tf4765307.h
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