Apparently, upto 188.8.131.52, the password file is opened and verified and then closed when an ALTER USER ... IDENTIFIED BY ... is issued for any database account.
[oracle@localhost ~]$ cd $ORACLE_HOME/dbs
[oracle@localhost dbs]$ ls -l orapw*
-rw-r----- 1 oracle oracle 1536 Jun 27 23:53 orapworcl
[oracle@localhost dbs]$ date
Wed Nov 2 23:12:27 SGT 2011
[oracle@localhost dbs]$ sqlplus hemant/hemant
SQL*Plus: Release 184.108.40.206.0 Production on Wed Nov 2 23:12:47 2011
Tom Kyte has repeatedly, repeatedly, repeatedly found fault with the usage of WHEN OTHERS -- particularly without a RAISE or RAISE_APPLICATION_ERROR.
See his article Why You Really Want to Let Exceptions Propagate (you need to scroll down the page) in the latest issue of Oracle Magazine.
Revisiting my earlier test on the same topic, I add a change to "slow" down the operations. The fetching of sequence values with the default cache was so fast in the earlier test, that the three sessions that I manually invoked to execute concurrently did not show a real distribution of data. The first session had retrieved very many sequence values and inserted rows before the second session had even started ...
During a forums discussion on START_REDEF, I created test cases in 10.2 and 11.2 to test DBMS_REDEFINITION to redefine a Partition (instead of using ALTER TABLE .... EXCHANGE PARTITION).
Automatic Segment Space Management ("ASSM") is designed to reduce block-level contention by multiple sessions concurrently attempting INSERTs by using a bitmap to identify blocks that are on the FreeList. The FreeList is accessed by sessions attempting to insert a row in a table when they need to identify "candidate" blocks. In Manual Segment Space Management ("MSSM"), it is the block-level storage parameter PCTUSED that is a determinant for when a block "enters" and "exits" the freelist.
A forums thread "Maximum number of Control Files" allowed me to express my opinions about why, for very practical reasons, Oracle does not allow very many multiplexed copies of the controlfile and why the controlfile is "limited" in size.
ALWAYS mention the actual Start and End Times and Contents of all backups.
In response to a forum thread "Why not selecting index path .", I ran up this example :
SQL> select banner from v$version where rownum=1;
Oracle Database 11g Enterprise Edition Release 220.127.116.11.0 - Production
SQL> drop table test_index_count5 purge;
SQL> alter system flush shared_pool;