Re: [bdbxml] Regular expressions in bdbxml

On Aug 18, 2005, at 11:19 AM, Dan Brian wrote:

> Gregory Burd wrote:
>
>
>> Thanks for raising this issue.  How important is this feature?
>> I happen to think that this will be a common use case.  If you do too
>> (this is a general question for the list not just Adam), drop me some
>> email and let me know.  The question is:
>>
>> "Should Berkeley DB XML support an index type that optimizes access
>> to data using regular expressions?"
>>
>
> It's impossible for any regular expression index to provide lookup  
> speed close to the current index types. All they can do is  
> dramatically lessen the set size for which the regular expression  
> must be executed against each record. And even then, it's usually  
> just for POSIX 1003.2 regexes, as opposed to PCRE, and implementing  
> "multigram" indexes is not a small job.
>
> But, yes, this would be a nice feature. :-)

Right, but that's what indexing is all about, reducing the set of  
potential matches to lower query processing time.  Here's one paper  
we're reviewing that has an interesting approach.

http://oak.cs.ucla.edu/~cho/papers/cho-regex.pdf

-greg

> Regards,
> Dan



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