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From: Steve Orr <>
Date: Wed, 5 Jul 2000 13:25:28 -0700
Message-Id: <>

Cut and Paste from page 3-9 of "Oracle8i Application Developerís Guide - Large Objects (LOBs)"

"The LOB index is an internal structure that is strongly associated with the LOB storage. This implies that a user may not drop the LOB index and rebuild it. Note that the LOB index cannot be altered. The system determines which tablespace to use for the LOB data and LOB index depending on the user specification in the LOB storage clause:

If in creating tables in 8.1 you specify a tablespace for the LOB index for a non-partitioned table, your specification of the tablespace will be ignored and the LOB index will be co-located with the LOB data. Partitioned LOBs do not include the LOB index syntax.

Specifying a separate tablespace for the LOB storage segments will allow for a decrease in contention on the table's tablespace."

Regarding... "The LOB index is an internal structure that is strongly associated with the LOB storage." Don't you just love the way the Oracle documentation spells everything out for us? ;-)

Steve Orr

-----Original Message-----
From: []On Behalf Of Steve Adams Sent: Wednesday, July 05, 2000 12:14 PM
To: Multiple recipients of list ORACLE-L Subject: RE: LOBINDEX

Hi Chuck,

The LOB index points to the chunks that comprise the LOB. Each index entry points to 4 chunks. Subject to PCTVERSION, changes to LOB data actually create new chunks. This generate redo for both the LOB data and index, but no undo for the LOB data. Read consistency and rollback are achieved merely by rolling back the LOB index changes. In 8.0 you can name the LOB index and store it in its own tablespace. In 8.1 you cannot.

Steve Adams

-----Original Message-----
From:	Chuck Hamilton []
Sent:	Thursday, July 06, 2000 3:34 AM
To:	Multiple recipients of list ORACLE-L

When I create a CLOB data type, oracle automatically creates a LOBSEGMENT and LOBINDEX segment. I understand the the LOBSEGMENT contains the LOB data. But what the heck is in the LOBINDEX? Why is it needed. Do I need to do anything with it? Is there some way to store it in a different tablespace than the LOBSEGMENT?

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Author: Steve Adams

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Received on Wed Jul 05 2000 - 15:25:28 CDT

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