I would investigate active session history.(through dba_hist_active_sess_history) If CBC latch contention is that dominant, active session history would show sessions which are waiting for "latch: cache buffers chains" event and the corresponding SQL statements. 2008/2/17, Jonathan Lewis <jonathan@xxxxxxxxxxxxxxxxxx>: > > > Insert into table - presumably with primary key index. > It doesn't matter what you insert or where, the root block of > the primary key index has to be hit as the PK entry is made. > > > Don't assume, by the way, that the TOP 'SQL by gets' is the > direct culprit; consider the top few - it's a strong indicator, but > look at what the SQL is doing, and look at the 'SQL by executions' > as well before jumping to conclusions. > > In your case, the top by gets is an INSERT. Consider, for example, > an insert on a simple, large, table with 5 indexes; this is likely to do > something like 20 gets (3 for each index that has to be updated, > plus a few to allow for the table and undo). The nature of the SQL > tells you something about the significance of the number of gets. > > Another point to consider when looking at the TOP sql statements - > maybe you have some double-counting going on. Is it at the top > because it calls a pl/sql function in it's 'where' clause, or in the > select, or values, clauses which runs another SQL statement that > is doing most of the buffer gets. > > Regards > > Jonathan Lewis > http://jonathanlewis.wordpress.com > > Author: Cost Based Oracle: Fundamentals > http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html > > The Co-operative Oracle Users' FAQ > http://www.jlcomp.demon.co.uk/faq/ind_faq.html > > > ----- Original Message ----- > From: "VIVEK_SHARMA" <VIVEK_SHARMA@xxxxxxxxxxx> > To: "Christian Antognini" <Christian.Antognini@xxxxxxxxxxxx> > Cc: <oracle-l@xxxxxxxxxxxxx> > Sent: Sunday, February 17, 2008 7:08 AM > Subject: RE: "latch: cache buffers chains" wait in NON-RAC Benchmark Runs > > > > Thanks Chris, folks > > In the Benchmark Run for Batch processes, Setting "_write_clones" to "0" > in > init.ora severely affected the performance Adversely & was removed > thereafter. > > Cause of the "latch: cache buffers chains" is believed to be "INSERT into > IDT > Table" as this SQL appears on TOP in the section of the "ordered by gets" > of the > Statspack Report. > > The IDT Table has 64 HASH partitions partitioned on field Account(A/c) > Number. > This is a Bank Accounts Interest processing Program & 1 Record gets > inserted per > Account into IDT Table per Run. Since Account Number is unique per > account, > could the INSERTs with different A/c Numbers still be accessing the SAME > Block? > > Any Other ideas? ... Will share the Statspack Report, if needed. > > Cheers > > Vivek > > -- > //www.freelists.org/webpage/oracle-l > > >