Using dictionary-managed tablespaces, it can sometimes take a very long time to drop or truncate a segment with many tens of thousands of extents, because Oracle takes a long time to update UET$ and FET$.
This can be a serious problem for some people because the session performing the DDL holds the ST enqueue for the duration of the extent deallocation. During these long extent deallocations, I observe the session performing DDL waiting on IPC with the database writer. Can anyone tell me why these long extent allocations spend the vast majority of their time waiting on DBW0? Does every block in UET$ and FET$ have to get written out before the deallocate can proceed? If so, why? Using a normal application, I can delete and insert tens of thousands of rows in just a few seconds. What takes Oracle so long with UET$ and FET$? BTW, this is not a problem that I personally have - it is a purely academic question. -- Jeremiah Wilton http://www.speakeasy.net/~jwilton -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Jeremiah Wilton INET: [EMAIL PROTECTED] Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
