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From Tatu Saloranta <>
Subject Re: commercial websites powered by Lucene?
Date Wed, 25 Jun 2003 03:26:19 GMT
On Tuesday 24 June 2003 07:36, Ulrich Mayring wrote:
> Chris Miller wrote:
> Well, nothing against Lucene, but it doesn't solve your problem, which
> is an overloaded DB-Server. It may temporarily alleviate the effects,
> but you'll soon be at the same load again. So I'd recommend to install

I don't think that would necessarily be the case. Like you mention later on, 
indexing data stored in DB does flatten it to allow faster indexing (and 
retrieval), and faster in this context means more efficient, not only sharing 
the load between DB and search engine, but potentially lowering total load?

The alternative, data warehouse - like preprocessing of data, for faster 
search, would likely be doable too, but it's usually more useful for running 
reports. For actual searches Lucene does it job nicely and efficiently, 
biggest problems I've seen are more related to relevancy questions. But 
that's where tuning of Lucene ranking should be easier than trying to build 
your own ranking from raw database hits (except if one uses OracleText or 
such that's pretty much a search engine on top of DB itself).

So, to me it all comes down to "right tool for the job" aspect;  DBs are good 
at mass retrieval of data, or using aggregate functions (in read-only side), 
whereas dedicated search engines are better for, well, searching.

> Of course, in real life there may be political obstacles which will
> prevent you from doing the right thing as detailed above for example,
> and your only chance is to circumvent in some way - and then Lucene is a
> great way to do that. But keep in mind that you are basically
> reinventing the functionality that is already built-in in a database :)

It depends on type of queries, but Lucene certainly has much more advanced 
text searching functionality, even if indexed content comes from a rigid 
structure like RDBMS. I'm not sure using a ready product like Lucene is 
reinventing much functionality, even considering synchronization issues?

So I would go as far saying that for searching purposes, plain vanilla RDBMSs 
are not all that great in the first place. Even if queries need not use 
advanced search features (advanced as in not just using % and _ in addition 
to exact matches) Lucene may well offer better search performance and 

-+ Tatu +-

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