Re: set transaction use rollback segment xxx

 In article <3r4ide$6el_at_lucy.infi.net>, gtravis_at_richmond.infi.net (Glenn Travis) writes:
> When using this statement; SET TRANSACTION USE ROLLBACK SEGMENT foo,
> does that transaction wait for the segment if it is in use?
>
> We have 4 small rollback segments (2MB each), and 1 large rollback
> segment(for batch at 230MB). I want to set the batch queries to use the
> large rollback segment. BUT, i can't prevent the other users from using
> it either. So what happens if a user grabs the first extent of my large
> rollback segment, then my batch job tries to use it? Does the batch job
> grab the next extent (which is considerably smaller), then run out of
> space? Or does it wait for the initial extent? How are these segments
> and extents shared and used? Should I break up my 230MB segment into
> smaller chunks?
>

You can keep your 'BIG' rollback segment offline until you need it for your batch job so that other transactions cannot use it. Put it back online before your 'SET TRANSACTION' command (see ALTER ROLLBACK SEGMENT command).

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Pierre Hollard                                 
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