Re: Rollback segment too small (-1555)
Date: 1996/05/13
Message-ID: <1996May13.132519.488_at_ns2>#1/1
In article <4mp0gr$1kn_at_uuneo.neosoft.com>, Stephen Kirk writes:
>Often when extracting large volumes of data from an Oracle table I recieve the message:-
>
>Rollback segment too small -1555
>
>This occurs even though I'm doing a select against the table and there are no other processes updating the table and activity on the
>database as a whole is light. We have 8 rollback segments each 1/2 gig in size. How can this be and what can I do to prevent it ? Is
>there a FAQ out there somewhere which addresses this issue ?
What you need are rollback segments that not only are able to grow 500 Mb but have grown close to 500 Mb. The problem with ORACLE is that it DOES NOT ALLOCATE EXTRA EXTENTS FOR READ CONSISTENCY. What we do is reserving a tablespace for rollback segments only; in your case it would be 4 Gb in size. We then create our rollback segments with
CREATE ROLLBACK SEGMENT [name] TABLESPACE [name] STORAGE (INITIAL 10M NEXT 10M MINEXTENTS 48 MAXEXTENTS 50); so that the rollback segment is almost at its maximum size on creation. We do NOT use OPTIMAL values, for that causes rollback segments to shrink again.
Good luck !
| Peter J.R. Vermaat | Dutch Department of Agriculture | Wageningen |
| p.j.r.vermaat_at_tfdl.agro.nl | http://gemini.tfdl.agro.nl:1024/~vermaat/ |
| Flagellant in Dreamland | ********************************************************************************Received on Mon May 13 1996 - 00:00:00 CEST