Re: Indexing a CLOB
- From: japplewhite@xxxxxxxxxxxxx
- To: zimsbait@xxxxxxxxx
- Date: Thu, 12 Feb 2009 13:42:38 -0600
Actually Context / interMedia / Oracle Text (the name changes over
releases) is perfect for indexing CLOBs - very fast. I used it with a
past company on Oracle8i. The only problem then was that domain indexes
couldn't be partitioned. With 9i and 10g I believe that restriction was
removed, which makes Oracle Text indexes and the tables they're on
partitionable. The search tools are rich and performance is great. I
highly recommend using out-of-line CLOBs - you have more options for
placing the CLOB segments and keeping your base table lean and fast wrt,
say, full table scans.
Jack C. Applewhite - Database Administrator
Austin I.S.D. - MIS Department
512.414.9715 (wk) / 512.935.5929 (pager)
z b <zimsbait@xxxxxxxxx>
Sent by: oracle-l-bounce@xxxxxxxxxxxxx
02/12/2009 11:46 AM
Please respond to
zimsbait@xxxxxxxxx
To
Ben.Wittmeier@xxxxxxxxx
cc
oracle-l@xxxxxxxxxxxxx
Subject
Re: Indexing a CLOB
What exactly is slow?
Context is used to search within lobs - probably not relevant here.
Try caching the lob.
alter table <table> modify lob (lob_name) (cache);
On Thu, Feb 12, 2009 at 11:40 AM, Ben Wittmeier <Ben.Wittmeier@xxxxxxxxx>
wrote:
>
> We need to increase the size of a data field beyond its varchar2(4000)
> definition because 4000 characters isn't large enough. The field is
> currently not indexed. The developer has done some initial testing with
> CLOB's but found the performance with the CLOB seemed slow so he's
> wondering about an index on the field. Though he also said the slow
> performance may be a result of the way he's doing things with the CLOB
> (as this is new to him). Are there any options available to index the
> CLOB field to improve performance? Oracle mentions using a CONTEXT
> index....
>
> Does anyone have any thoughts on indexing CLOB fields?
>
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