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From Terry Rosenbaum <Te...@amicas.com>
Subject Re: xpath with index after data is added does not work
Date Thu, 06 Nov 2003 04:27:29 GMT
Speaking of my knowledge of the indexing system
and observations WRT 1.1b1:

String Indexes with patterns like
"element", "element@id" and "*@id" should
work fine.

I would not expect a pattern like "metatable/*/*@id" to work -
the only acceptable patterns are as shown above. There
is no hierarchical addressing in the indexing system.

Indexes are automatically updated as Resources are
added and/or removed.

When an index is created, the population of that index is
performed "in the background" by another thread. If there
are already Resources in the Collection, time must be allowed
for index population to complete before you will see the
performance impact of the index (if any).

The comparisons used to implement numeric indexing are
broken. So, an index defined with, e.g., type="long"
will not work properly. Indexes with type="string" work
as expected. But, comparing numbers as strings generally
will not yield the hoped-for result for non-equality comparison
operators (e.g. [@id>5] with a string index. See bug #19203 
<http://nagoya.apache.org/bugzilla/show_bug.cgi?id=19203>. 
(http://nagoya.apache.org/bugzilla/show_bug.cgi?id=19203)

-Terry

matt ma wrote:

>What version are you using Andrew?  I'm using 1.1b1
>and noticed that if you add index with 
>-p *@id  
>and you have id attributes in multiple levels of your
>xml file you will end up with no results on xpath
>quering [@id=?].  However, I was able to get this to
>work by specifying the level
>metatable/*/*@id
>xpath with this index does return results but no
>significant performance gain so I'm wondering if it
>works at all.
>
>For the indexes that work I am seeing significant
>performance improvements (~3x) for my db.
>
>I'm trying to figure out if indexes by design do not
>update themselves like they do in a normal database or
>if this is a bug.
>
>-matt
>
>--- Andrew White <Andrew.E.White@motorola.com> wrote:
>  
>
>>Xpath with attribute indexes is (to the best of my
>>experimentation) broken.
>>I can't even get xindice to show results when I
>>delete and recreate the
>>index (works when deleted, putting it back breaks it
>>again).
>>
>>I also noticed that (when I first created the index)
>>I got about a 2x
>>performance gain on command line searches, but a
>>very slightly negative
>>effect on embedded searches.
>>
>>Anyone else?
>>
>>-- 
>>Andrew White
>>    
>>
>
>
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