PCTUSED, PCTFREE... help, help

Having a hard time finding out just where these things seemed to have all but disappeared.  

Listing tables in one of my tablespaces I have the combinations of:

Pct_Free      Pct_Used
Null           null
10            null
10            40
 

It seems I can SET pct_free, but while it tells me it will set pct_used, the select always comes up null.  

Now I assume that this has to do with auto management, but where are the rules and if for some reason we needed to tweak them, how would we go about doing that.  

We converted databases and used import/export to move them to a new box. On the old box it was mostly 10/40, but on the new box we are finding 10/null. The user is claiming that it is much slower all because we don't have the 40 in pct_used. I bet it's been 8 years since I played with the setting and found the "opportunity" listed above. I would think the auto management would take care of this for us.  

Is there a good write up on it some place? Haven't found much other than "how to set" and that doesn't seem to be working. Database is 10.2.0.3 on HP/UX.  

Michael Kline
Database Administration
Richmond, Va. 23227
BlackBerry: 804.517.7443         

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