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From Otis Gospodnetic <>
Subject Re: Advanced timestamp usage (or global value storage)
Date Wed, 25 Aug 2004 15:25:13 GMT
What if all Documents in your index contained some flag field + an 'add
date' field.  Then you could make a query such as: flag:1 and sort it
by 'add date' field, taking only the very first hit as the most
recently added Document.


--- Avi Drissman <> wrote:

> I've used Lucene for a long time, but only in the most basic way. I 
> have a custom analyzer and a slightly hacked query parser, but in 
> general it's the basic add document/remove document/query documents 
> cycle.
> In my system, I'm indexing a store of external documents, maintaining
> an index for full-text querying. However, I might be turned off when 
> documents are added, and then when I'm restarted, I'm going to need
> to 
> determine the timestamp of the last document added to the index so
> that 
> I can pick up where I left off.
> There are three approaches to doing this, two using Lucene. I don't 
> know how I would do the two Lucene approaches, or even if they're 
> possible.
> 1. Just keep a file in parallel with the index, reading and writing
> the 
> timestamp of the last indexed document in it. I know how to do this, 
> but I don't like the idea of keeping a separate file.
> 2. Drop a timestamp onto each document as it's indexed. I've attached
> timestamp fields to documents in the past so that I could do range 
> queries on them. However, I don't know how to do a query like "the 
> document with the latest timestamp" or even if that's possible.
> 3. Create a dummy document (with some unique field identifier so you 
> could quickly query for it) with a field "last timestamp". This is a 
> "global value storage" approach, as you could just store any field
> with 
> any value on it. But I'd be updating this timestamp field a lot,
> which 
> means that every time I updated the index I'd have to remove this 
> special document and reindex it. Is there any way to update the value
> of a field in a document directly in the index without removing and 
> adding it again to the index? The field I'd want to update would just
> be stored, not indexed or tokenized.
> Thanks for your help in guiding my exploration into the capabilities
> of 
> Lucene.
> Avi
> -- 
> Avi 'rlwimi' Drissman
> Argh! This darn mail server is trunca
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