This will not resolve the 'buffer busy wait' scenario. The contention is for blocks that are already in the SGA.
Regards, Malcolm. -----Original Message----- Sent: Tuesday, November 27, 2001 9:15 AM To: Multiple recipients of list ORACLE-L Hi I would try to set the table to cache mode. It seams that the blocks are aged out from buffer - which is default for FTS. alter table BBN_SRVvignette cache; to avoid reloading into cache. Ivo ____________________________________________________________________ Ivo Libal, Bc. Design & Development, Warehousemanagementsystems Dept. KNAPP Systemsintegration GmbH Waltenbachstraße 9 A-8700 Leoben, Austria Phone: ++43/3842/805-0 e-Mail: [EMAIL PROTECTED] "Thorns, Malcolm (NESL-IT)" <Malcolm.Thorns@northern-elect An: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]> ric.co.uk> Kopie: Gesendet von: [EMAIL PROTECTED] Thema: RE: Buffer Busy Waits -- Sanity check please 11/27/2001 09:25 AM Bitte antworten an ORACLE-L Jeff, The 3 sessions are doing the same (or similar) queries. In this case count(*) which is forcing a full table scan of the table in each session. The 3 sessions are thus trying to access the same blocks from the SGA, in the same order. Only 1 session can access a block in the SGA at a time - this is the session showing 'db file scattered read'. The other 2 sessions need to wait for the block (these waits show as 'buffer busy waits' - ie waiting for the block in the SGA). You will see the block id (and perhaps the file id) changing as the FTS's progress. Thus the sessions are 'chasing' each other through the blocks - holding each other up with SGA block contention - which shows up as 'buffer busy waits'. Hope that explains things. Regards, Malcolm -----Original Message----- Sent: Monday, November 26, 2001 11:21 PM To: Multiple recipients of list ORACLE-L We recently had a new website go live. Since then, I'm seeing constant buffer busy waits and after a period of time, I see sessions hung on the same block#. The SQL query is always a COUNT(*) (below). It's almost as though one session has a lock of some sort in the buffer cache and other sessions are blocked. Although, I've checked and there's no DML ongoing, so I'm unsure as to why we would see this. Note that v$session shows 78 and 393 to be INACTIVE, while 159 is ACTIVE. So it's like 159 can't write to the buffer cache because 78 and 393 have a lock there. Note that these are all defined as persistent connections, via the Vignette front-end. I'm sure all the clues are there but my brain is too fuzzed to piece it together. SID SQL_TEXT O/S User ----- ---------------------------------------------------------------- --------------- 159 SELECT COUNT(*) NUM,SUM(TOTAL_CHARGE_AMT) TOT FROM BBN.BBN_SRV vignette 159 _PAID_WARR_CLAIM WHERE CUSTOMER_ID = :b1 AND ENTERPRISE_CD = : vignette 159 b2 AND (CHECK_ID IS NOT NULL AND CHECK_ID != 'PENDING' ) vignette SID EVENT P1TEXT P1 P2TEXT P2 P3TEXT P3 ----- -------------------------- ------------ -- ----------- ------ ----- ------ 78 buffer busy waits file# 72 block# 109177 id 130 393 buffer busy waits file# 72 block# 109177 id 130 159 db file scattered read file# 72 block# 109177 blocks 8 -------------------------------------------- Jeffery D Thomas DBA Thomson Information Services Thomson multimedia Inc. 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Northern Electric plc Carliol House Market Street Newcastle-upon-Tyne NE1 6NE Registered in England and Wales: Number 2366942 ******************************************************************************************** -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Thorns, Malcolm (NESL-IT) 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).