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From "Chris Lu" <chris...@gmail.com>
Subject Re: Why indexing database is necessary? (RE: indexing database)
Date Tue, 04 Mar 2008 22:27:11 GMT
Hi, Nick,

Lucene Index in a sense is more like another kind of database indexes,
because it's inverted, etc.

If we ask why we need many database indexes, the answer is, different
query execution path.
Same thing for Lucene index, which is faster for term matching.

Lucene index actually can do more. For example, facet-search, which
tells you how many matches in each category(facet), in addition to the
matched results. This way is more convenient for websites to display
results, and provide additional links for users to narrow down the
results.

-- 
Chris Lu
-------------------------
Instant Scalable Full-Text Search On Any Database/Application
site: http://www.dbsight.net
demo: http://search.dbsight.com
Lucene Database Search in 3 minutes:
http://wiki.dbsight.com/index.php?title=Create_Lucene_Database_Search_in_3_minutes
DBSight customer, a shopping comparison site, (anonymous per request)
got 2.6 Million Euro funding!


On Tue, Mar 4, 2008 at 11:28 AM, Duan, Nick <NDuan@mcdonaldbradley.com> wrote:
> Hmm, I guess that's because a database query returns a list of records,
>  whereas search engine returns only the links, not the actual content.
>  So a search engine works only in the index space, whereas a database
>  query engine would have to work in both index and content space...
>
>
>  ND
>
>
>
>  -----Original Message-----
>  From: Will Johnson [mailto:willjohnsonsearch@gmail.com]
>  Sent: Tuesday, March 04, 2008 2:18 PM
>  To: java-user@lucene.apache.org
>  Subject: RE: Why indexing database is necessary? (RE: indexing database)
>
>  Don't forget the number 1 reason: speed.  For certain types of queries a
>  search engine can return results orders of magnitude faster than a
>  database.
>  I've seen search engines return hits in hundreds of milliseconds when
>  the
>  same database query took hours or even days.  That's not to say that a
>  search engine is always better, just the it often times is for when the
>  inputs and outputs are carefully defined.
>
>  - will
>
>  -----Original Message-----
>  From: Darren Hartford [mailto:dhartford@ghsinc.com]
>  Sent: Tuesday, March 04, 2008 1:52 PM
>  To: java-user@lucene.apache.org
>  Subject: RE: Why indexing database is necessary? (RE: indexing database)
>
>  Indexing with lucene/nutch on top of/instead of DB indexing for:
>
>  1) relativity scoring
>  2) alias searching (i.e. a large amount of aliases, like first names)
>  3) highlighting
>  4) cross-datasource searching (multi DB, DB + XML files, etc).
>
>  As for best approach to externally index, I do not have any direct
>  pointers.  I would recommend looking at an ETL tool that can be extended
>  for this purpose (I've started writing a plugin for Pentaho, but got
>  pulled off and haven't finished it -- and that was for Solr, not
>  lucene/nutch).
>
>  -D
>
>  > -----Original Message-----
>  > From: Duan, Nick [mailto:NDuan@mcdonaldbradley.com]
>  > Sent: Tuesday, March 04, 2008 1:33 PM
>  > To: java-user@lucene.apache.org
>  > Subject: Why indexing database is necessary? (RE: indexing database)
>  >
>  > Could anyone provide any insight on why someone would use nutch/lucene
>  > or any other search engines to index relational databases? With use
>  > cases if possible?  Shouldn't the database's own indexing mechanism be
>  > used since it is more efficient?
>  >
>  > If there is such a need of indexing the database content using search
>  > engines, what would be the best approach other than de-normalizing the
>  > database?
>  >
>  > Thanks a lot in advance!
>  >
>  > ND
>  > -----Original Message-----
>  > From: payo [mailto:payo22@yahoo.com]
>  > Sent: Tuesday, March 04, 2008 12:36 PM
>  > To: nutch-user@lucene.apache.org
>  > Subject: indexing database
>  >
>  >
>  > hi to all
>  >
>  > i can index a database with nutch?
>  >
>  > i am use nutch 0.8.1
>  >
>  > thanks
>  > --
>  > View this message in context:
>  > http://www.nabble.com/indexing-database-tp15832696p15832696.html
>  > Sent from the Nutch - User mailing list archive at Nabble.com.
>  >
>  >
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