Re: locally managed tablespace - autoallocate

The problem with trying to predict the next extent size when autoallocate is in use is that the underlying algorithm is subject to change with any release according to Oracle. Also depending on the Oracle version in use and the history of the tablespace: build as LMT or converted the pctincrease parameter still affects the allocated extent size. Then again so does the initial extent request size. It is very possible to get the initial extent size at 1M even when most objects in the tablespace start at 64K. Finally, if the next extent size is unavailable in an auto-allocate tablespace then if is possible for Oracle to chose to allocate a smaller extent size, but there is no guarentee that Oracle will not issue an error.

None of this is to say that you cannot write a useful routine to monitor and predict space availability for an autoallocate tablespace, it is just that any such routine will have some potentially serious limitations.

Based on Connor McDonald testing from 2002
- auto-alloc extents are 16x64k, then 64x1m, then 120x8m, then 64m,
when
the initial_extent is less than 1m
- auto-alloc extents are 64x1m, then 120x8m, then 64m, when the
initial_extent is equal/more than 1m

HTH -- Mark D Powell -- Received on Wed Dec 08 2004 - 21:40:50 CST