Re: Tuning for LONG RAW

Allen Hadden wrote:
>
> Our database will need to process a relatively small
> number of very large transactions (RTF documents
> stored as LONG RAW values). These documents can be
> pretty big (sometimes > than 2 MB).
>
> The question I have is how should we tune the database.
> I assume that the extent sizes for the tablespaces and
> rollback segments will need to relatively large, but
> how can I determine the best size. Also, how should
> the "OPTIMAL" rollback segment parameter be choosen?

  The size estimation highly depends on your total sizes. As there is a large long raw field, you can consider use it for estimation. For instance, if you estimate you have 10 0 records of 5MB RTF files on average, the INITIAL can be set to 515 for overhead and the space for other columns.

  For rollback segment, you can use MONITOR ROLLBACK to monitor the setting of OPTIMAL. Following is a table:

  Shrink counts  | Sizes to be shrunk         | Conclusion
  Low              Low                            Excellent setting if average sizes
 						  = optimal sizes. Otherwises, OPTIMAL
					          is too high
  Low              High                           Excellent
  High             Low                            OPTIMAL is slightly lower
  High             High                           Periodic long transactions occur
  

  Alternatively, you can use v$rollstat to monitor the contentions of the header of the rollback segments.

---
Name   : Lun Wing San (Certified Oracle Database Administrator)

Title  : Oracle Application Developer of Hong Kong Productivity Council
         Oracle Database Administrator and System Administrator of QRC
Phone  : (852)27885841

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