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From Yonik Seeley <>
Subject Re: "Advanced" query language
Date Tue, 06 Dec 2005 02:07:59 GMT
On 12/5/05, Erik Hatcher <> wrote:
> Having an XML format representing a Query
> and a mechanism to parse it into an actual Query instance makes a lot
> of sense.

Certainly.  A representation is needed where it is very easy to add
support for new queries, flexible enough to handle *all* query types,
and can easily accomodate change (such as minNrShouldMatch being added
to BooleanQuery).

XML is still far and away the most popular, and hence that makes the most sense.

> The proposed LISP, Python, etc formats don't add anything
> to the equation, and actually complicate it.

Yes, scripting is rather orthogonal to query representation.

There is one little problem with XML though...  It's inability to
directly represent binary data, or even all unicode code points (no,
entities don't fix this).  I use binary data in lucene to represent
some numerics, and that can't be represented in standard XML.  An
application specific escaping mechanism can be used, but then you are
a step away from standard XML.

example:  <tag>&#0;</tag> is not valid XML

If we go with XML, I think this must be solved (or else we are at the
point where we can only represent a subset of queries that lucene can
handle again).


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