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Kastaka avatar image
Kastaka asked

LOB_segname in varray_col_properties clause of CREATE TABLE - what does this refer to?

There's a property called 'LOB_segname' in the varray_col_properties clause of CREATE TABLE, but the documentation on that clause is a little sparse.

Is there some kind of LOB segment entity in the database this refers to, or what?

tablelob
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Andrew Mobbs avatar image
Andrew Mobbs answered

LOBs are (usually) stored in their own segments, the table only has a pointer to the data. The LOB segment is implicitly created when you create a LOB column on a table.

The Concepts manual has an overview: http://download.oracle.com/docs/cd/E11882_01/server.112/e10713/cncptdev.htm#CHDHBGHD

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HillbillyToad avatar image
HillbillyToad answered

If you have a LOB column, this gives you the opportunity to explicitly specify how Oracle physically stores the LOB. Do you care if Oracle uses a system generated SEGMENT name for your LOB?

Do you understand what a segment is?

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I thought I did, but it confuses me that they're something you might want to / be able to refer to by name...
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Good question. Off the top of my head, it might be nice to know that the chained rows i'm running into with my blocks belongs to the LOB in my table. I'd know that if the segments were named by me vs the system. I'm sure there are other better reasons...
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