Xapian discuss - Apr 2009 - Search docs with terms that match a pattern

Hello,

I have once again a small question: Is it possible to search a pattern
like "*foo*" ? I saw that we can use QueryParser::FLAG_WILDCARD but
only with "foo*" patterns. Have you got a trick to do that ?

And an other question with wildcards: i tested FLAG_WILDCARD and the
QueryParser, but i have some problems with special characters (by
example "/"). Is it possible to use escape characters to do that? I
tried "\/", but without good results. The problem is that your terms
are often "id", or something like that, with a lot of special
characters :-(

By advance, thank you for your answer,

Best regards,
David V. 


-- 
David Versmisse
Itaapy <http://www.itaapy.com>         Tel +33 (0)1 42 23 67 45
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On Tue, Apr 07, 2009 at 10:33:12AM +0200, David Versmisse
wrote:
> I have once again a small question: Is it possible to search a pattern
> like "*foo*" ? I saw that we can use QueryParser::FLAG_WILDCARD
but
> only with "foo*" patterns. Have you got a trick to do that ?
No, only trailing wildcards are supported.  To support simultaneous
leading and trailing wildcards without the performance sucking, we'd
need to maintain a copy of the termlist structured in a way which allows
efficient regexp searching.
> And an other question with wildcards: i tested FLAG_WILDCARD and the
> QueryParser, but i have some problems with special characters (by
> example "/"). Is it possible to use escape characters to do that?
I
> tried "\/", but without good results. The problem is that your
terms
> are often "id", or something like that, with a lot of special
> characters :-(
An id term makes a lot more sense as a boolean term rather than a
probabilistic one - it's not a word and you don't want it stemmed.  And
boolean terms can contain "/".

But wildcards on boolean terms aren't supported.  They could be, but a
boolean term can of course contain literal "*", so you'd need to
support
some sort of escaping.  There's some discussion of that here:

http://trac.xapian.org/ticket/128

Cheers,
    Olly