Gee, John, I was not aware of this underscore parameter. In my 9.2 database it's 6, just as yours.
I did my test using upto three concurrent tranactions; guess I'll need to test with 7 or more. However, even if 7 concurrent transactions update the block's rows, and the limit is 6, then the waits should be based in ITL (Interested Trasnaction List) Waits, not BBW. since this is not due to a session not being able to get a particular buffer to the SGA, rather the lack of resources to get the CR copy of a buffer. Has anyone done this test? I'll certainly take it up later to build up on my upcoming article on ITL Waits. Regards, Arup ----- Original Message ----- To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> Sent: Wednesday, February 19, 2003 2:45 PM > Arup, > > Just picking up the thread on the BBWs. (Btw, I asked this question in this > list - never got an answer!) The following undocumented parameter limits the > numbe of CR copies in the Block buffers. > > Name Value > --------------------------------------------- ---------------------------- -- > Description > -------------------------------------------------------------------------- -- > --- > _db_block_max_cr_dba 6 > Maximum Allowed Number of CR buffers per dba > > What if there are more than 6 concurrent update requests for the same block. > Would that not result in BBW? > > John Kanagaraj > Oracle Applications DBA > DBSoft Inc > (W): 408-970-7002 > > Disappointment is inevitable, but Discouragement is optional! > > ** The opinions and statements above are entirely my own and not those of my > employer or clients ** > > > > -----Original Message----- > > From: Arup Nanda [mailto:[EMAIL PROTECTED]] > > Sent: Wednesday, February 19, 2003 8:24 AM > > To: Multiple recipients of list ORACLE-L > > Subject: Re: Automatic Segment Space Management > > > > > > Jay, > > > > I have been using ASSM for last five months in our Datawarehouse > > environment. Haven't had a chance to play with the OLTP side, yet. > > > > Inserts are way faster as compared to system managed extent > > allocation. I > > read Don's article on DBAZINE. However, I would like to add > > one caveat here: > > ASSM does not *eliminate* buffer busy waits as the article claims; it > > *reduces* them. BBW occur due to concurrent access to a > > buffer by more than > > one session. This will be the case regardless of number of > > freelists. While > > ASSM eliminates the freelist contention - thereby reducing > > BBW in inserts - > > it does not reduce the likelihood that more than one sessions > > will try to > > get the same block to the buffer cache simulataneously. > > > > Table drops appear a little slower in ASSM; but that could be > > wrong - I > > never timed dropping a table in the system managed mode. > > > > HTH. > > > > Arup Nanda > > > > > > ----- Original Message ----- > > To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> > > Sent: Wednesday, February 19, 2003 9:33 AM > > > > > > > I'm continuing to introduce myself to 9i. I've been reading about > > Automatic Segment Space Management, and I just wondered if > > anybody had any > > positive/negative experiences with it. I got some good info at: > > > > > > http://www.dbazine.com/burleson11.html > > > > > > > > > Thank you, > > > > > > > > > Jay Hostetter > > > Oracle DBA > > > D. & E. Communications > > > Ephrata, PA USA > > > > > > > > > > > > **DISCLAIMER > > > This e-mail message and any files transmitted with it are > > intended for the > > use of the individual or entity to which they are addressed > > and may contain > > information that is privileged, proprietary and confidential. > > If you are not > > the intended recipient, you may not use, copy or disclose to > > anyone the > > message or any information contained in the message. If you > > have received > > this communication in error, please notify the sender and > > delete this e-mail > > message. The contents do not represent the opinion of D&E > > except to the > > extent that it relates to their official business. > > > -- > > > Please see the official ORACLE-L FAQ: http://www.orafaq.net > > > -- > > > Author: Jay Hostetter > > > INET: [EMAIL PROTECTED] > > > > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > > > San Diego, California -- Mailing list and web > > hosting services > > > > > --------------------------------------------------------------------- > > > 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). > > > > > -- > > Please see the official ORACLE-L FAQ: http://www.orafaq.net > > -- > > Author: Arup Nanda > > INET: [EMAIL PROTECTED] > > > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > > San Diego, California -- Mailing list and web hosting services > > --------------------------------------------------------------------- > > 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). > > > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net > -- > Author: John Kanagaraj > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > San Diego, California -- Mailing list and web hosting services > --------------------------------------------------------------------- > 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). > -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Arup Nanda INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- 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).
