Re: question about progress of shrink operation

I've just run a quick test of "alter table t1 modify lob(text_content) (shrink space)" on 19.11, and it objects ( ORA-10635: Invalid segment or tablespace type) if the lob is defined as securefile. However, basicfile has no problem. I can't find any comment about this in the 19c SQL Reference manual under "alter table", but the 21c manual says that "under 21c the shrink space command can be used for securefile lobs", so presumably the 19c documentation has an error of omission.

Running a test that using basicfiles it seems that every lob value that has to move will start a new transaction (which suggests that if the shrink fails the lobs will stay in the new location). It is an interesting detail that while the shrink involves a large number of separate transaction the session picks one undo segment and does all the work in that one segment.

Regards
Jonathan Lewis

On Fri, 26 Jan 2024 at 08:42, Laurentiu Oprea <laurentiu.oprea06_at_gmail.com> wrote:

> Dear all,
>
> What will happen with progress of a shrink operation of a CLOB if it fails
> due to various reasons like for example undo space. Will it be all lost or
> partially lost or no lost progress?
>
> THank you.
>

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