Managing Dynamic Allocation of Extents?

I couldn't understand why the value I chose for a next extent was being overridden until I
read that Oracle7 may dynamically modify size of extents based on rounding criteria and
available storage space. I can see advantages with Oracle doing this (e.g. maximizing
reuse of extents). On the other hand, wouldn't there be times when you may want to
override these dynamic sizes?

Note the following example: Within an empty tablespace of 100M (1 datafile), I created
an index with an initial extent size of 45M and next extent 600K. As a result, I was
expecting an initial extent of 45M and about forty 600K extents (I realize this may not be
optimum sizing). Instead, I got an initial of 45M and one next extent of 32M! That's a
big jump in next extent size and one that I don't want. It's probably a result of the
tablespace being empty at the time but I did plan on creating more segments in there.

Is there any way to override dynamic sizing? Or must I keep trying different extent sizes
until I get acceptable dynamic sizes as a result? I'm a relatively new DBA so maybe I'm
missing something here. It just seems that it would be nice to have more control over this
sizing at times.

Any feedback is much appreciated...

Rick Papaj
papaj_at_acsu.buffalo.edu
State University of New York at Buffalo Received on Thu Apr 02 1998 - 00:00:00 CST