Oracle internals, debugging and undocumented features
I had a very interesting case today when database hang and I was not able to make connection..
First thing I had in mind was to generate system state dumps.In the past I used debugger but I remember that sqplus has option which makes database connection “light” meaning it doesn not create session but has limited access to SGA…
It has been arround since 10g… It’s called preliminary connection.There are two options to :
1) sqlplus -prelim / as sysdba
2) sqlplus /nolog
set _prelim on
conn / as sysdba so I tried…
-bash-3.1$ sqlplus /nolog
SQL*Plus: Release 184.108.40.206.0 – Production on Thu Sep 25 18:04:28 2008
Copyright (c) 1982, 2007, Oracle. All rights reserved.
SQL> set _prelim on
SQL> conn / as sysdba
Prelim connection established
SQL> oradebug setmypid
SQL> oradebug unlimit
SQL> oradebug dump hanganalyze 1
SQL> oradebug dump systemstate 10
SQL> oradebug tracefile_name
let’s see what we can see using this preliminary connection…
to be continue….