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From markharw00d <>
Subject Re: Lucene database bindings
Date Sat, 17 Sep 2005 15:00:21 GMT
Mag Gam wrote:

>Does your example store the index in the derby db or somewhere else? I was 
>thinking of indexing a table in a seperate column.
The software is not an implementation 
ie an FSDirectory alternative for persisting Lucene data in a relational 
Instead, the software demonstrates a way to extend SQL syntax to allow 
Lucene queries to run as in-line functions during the database's 
execution of queries. These hybrid SQL statements can take advantage of 
the usual databases functions for sorting, grouping joins, conditions, 
indexes etc but also use Lucene queries and highlighting functions all 
in the one SQL statement.
The Lucene indexes used as part of this can be any standard Directory 
implementation (eg RAM, FS).

The motivation for creating a Lucene/RDBMS hybrid query tool was to 
address issues commonly associated with using just Lucene:
1) Sorting on float/date fields and associated memory consumption
2) Representing numbers/dates in Lucene (eg having to pad with sufficent 
leading zeros and add
to index's list of terms)
3) Retrieving only certain stored fields from a document (all storage 
can be done in db)
4) Issues to do with updating *volatile* data eg price data used in sorts
5) Manually coding joins with RDBMS content as custom filters
6) Too-many terms exceptions produced by range queries
7) Grouping results eg by website
8) Boosting docs based on stored content eg date

These are the sorts of things an RDBMS can help with.


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