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community!

I have a table with three SecureFile LOBs in it (lets name them A, B, C) and I want to compress them.

At first I wanted to do it in three parts, every time moving and compressing one specific LOB. I tried the following command:

alter table MYTABLE
move lob (A) store as (compress)
online
parallel 4;

It looks like ORACLE not only compresses and moves LOB A, but also it moves B and C! I decided this from the space consumption: there are three new temporary segments, two of which are getting close to the original LOB sizes.

Is it true that ALTER TABLE MOVE command implicitly moves all the LOBS within the table? Can I split my work in three parts or should I go with one alter table move lob(A) lob (B) [...] lob (N) command?

My Oracle version is 19c.

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    Please be aware that LOB compression requires the Advanced Compression license, and that is very expensive. If you haven't already have purchased AC licences to cover this database, I wouldn't use securefile LOB compression at all.
    – Paul W
    Feb 23, 2023 at 22:02

1 Answer 1

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Actually, if you would create table with only 1 lob column, move statement will create three temporary segments anyway

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