Oracle Lucene Domain Index
(http://docs.google.com/View?docid=ddgw7sjp_569gf8c7cd8), this zip is
valid for 10g and 11g database version (10g using back-ported classes
from 1.5 to 1.4)
This release is compiled using Lucene 3.0.2 version and incorporates a
set of new features added, here the list:
* Added a long awaited functionality, a parallel/shared/slave search
process used during a start-fetch-close and CountHits function
* Added lfreqterms ancillary operator returning the freq terms array
of rows visited
* Added lsimilarity ancillary operator returning a computed
Levenshtein distance of the row visited
* Added a ldidyoumean pipeline table function using
* Added test using SQLUnit
The bigger addition is the Parallel-Shared-Slave search process, this
architectural change was in my to-do list for a long time and finally
I added in this release :)
The idea behind this is to have a new Oracle process started by the
DBMS_SCHEDULER sub-system during the database startup process and
stopped immediately before shutdown.
Now this process is responsible for implementing the ODCI methods
start-fetch-close/count-hit on behalf of the client process (process
associated to an specific user session) which connect to the
shared-slave process by using RMI.
With this new architecture we have two principal benefits:
* Reduce memory consumption
* Increase Lucene Cache Hits
Less memory consumption because the internal OJVM implementation is
attached to a client session, so the Java space used by Lucene
structures is isolated and independent from another concurrent
session, now all Lucene memory structures used during index scan
process are created in a shared process and then not replicated.
Also if one session submits a Lucene search, this search is cached for
subsequent queries, all subsequent queries coming from the same client
session or any other which are associated to the same index and with
the same Query string implies a hit.
For those who are in the SFO area, I'll be there next week during the OOW10 :)
Marcelo F. Ochoa
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