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From David Buchmann <david.buchm...@liip.ch>
Subject Re: Strange Search Performance problem with OR
Date Tue, 27 Mar 2012 07:10:56 GMT
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i think the 2 queries are not equivalent. the first one is equivalent to

...
WHERE data.guid = 'J7B1X'
  AND (ISDESCENDANTNODE(data, '/article')

plus

WHERE
 ISDESCENDANTNODE(data, '/import/article')

(if you want the data.guid = ... to apply to both, you need paranthesis)

but if /import/article is almost empty, i still don't see why the
combined query should take so long unless jackrabbit/lucene are doing
something stupid.

cheers,david

Am 26.03.2012 22:28, schrieb Christian Stocker:
> Hi
> 
> We have the following search query
> 
> 
> SELECT * FROM [own:unstructured] AS data WHERE data.guid = 'J7B1X'
> 		AND (ISDESCENDANTNODE(data, '/article')
> 		OR ISDESCENDANTNODE(data, '/import/article')
> 		)
> 		ORDER BY firstImportDate DESC
> 
> 
> This query can take quite some time (up to 3 seconds, but it gets more
> and more hte more data we have). In /article there's potentially a lot
> of nodes, in /import/article usually almost nil.
> 
> 
> If we now separate the query into 2:
> 
> SELECT * FROM [own:unstructured] AS data WHERE data.guid = 'J7B1X'
> 		AND ISDESCENDANTNODE(data, '/article')
> 		ORDER BY firstImportDate DESC
> 
> and
> 
> SELECT * FROM [own:unstructured] AS data WHERE data.guid = 'J7B1X'
> 		AND ISDESCENDANTNODE(data, '/import/article')
> 		ORDER BY firstImportDate DESC
> 
> Both queries take approx. 10ms (and return 0 or 1 resultset, more is not
> possible). So quite fast.
> 
> Can anyone explain to me, why that is and how we could rewrite the query
> to make it fast with a single one as well?
> 
> Thanks
> 
> chregu

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