On 29 Nov 2003, at 01:19, Erik Hatcher wrote:
On Friday, November 28, 2003, at 07:42 AM, Oliver Zeigermann wrote:p.s. I don't have time to really get deep into DASL within Slide just yet, but I am in the midst of co-authoring a book on Lucene - so if anyone needs any assistance I'd be more than willing to answer questions or assist in some minor ways. I do have big plans with Slide and Lucene in the near future once the book is done, so this is definitely an area of keen interest for me.
We were discussing if it was possible to use Lucene not only for full text, but also for property indexing. Maybe using fields? Then for properties like size and "date of last change comparators" like < and > would be great. I do not think this is supported by Lucene, is it? Could it be possbile / reasonable to extend Slide for this?
Yes, Lucene could definitely do a nice job with properties. The only trick is to represent numbers and dates in a lexicographic order. Lucene supports dates natively [ see Field.Keyword(String, Date) ] - although I'm not fond of the idiosyncracies the built-in date support has. If you want to represent just a date, YYYYMMDD does the trick nicely. Numerics work fine too, as long as they are textually ordered - (padded with zeros when indexed as a Keyword field). RangeQuery works great to do searching of < and > operators.
I think you'll find that Lucene will serve Slide's needs nicely - you'll just have to be a little creative in how you build Lucene Document objects and break things into fields. Lucene is a "flat" structure - so implying hierarchy requires some thought - perhaps just the URI will work to give you the hierarchy you need. But if properties are also hierarchical (can't non-live, "dead"?, properties contain an entire DOM tree?) then things will get more interesting and tricky.
Hmmm, seems to me like trying to fit a square into a rounded hole. Can you elaborate more on how you would do a query like
SELECT {DAV}allprop
FROM /files/whatever
WHERE {DAV}contentlength > 40000
ORDER BY {DAV}lastmodifiedon top of lucene?
-- Stefano.
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