APPLIES TO:

Oracle Database - Enterprise Edition - Version 10.2.0.1 to 12.1.0.2 [Release 10.2 to 12.1]
Information in this document applies to any platform.
***Checked for relevance on 21-Jul-2017***

GOAL

Show a way to connect to a database through sqlplus when all other connection methods are hanging. Using a sqlplus preliminary connection you will be able to connect to the database since no session is actually created,but you will have limited access to the SGA. This will help in capturing diagnostic information like a systemstate dump to aid in problem resolution.

SOLUTION

There are two ways to connect to sqlplus using a preliminary connection.

1. sqlplus -prelim / as sysdba
   
   

2. sqlplus /nolog
   set _prelim on
   connect / as sysdba
   
   

For example:

sql> set _prelim on
sql> connect / as sysdba
Prelim connection established

REFERENCES

NOTE:61552.1- Oracle 9i and Below: Exhaustive Troubleshooting Steps for Oracle Database Hanging Issues