ORA-00018 Maximum number of sessions exceeded

Cause: All session state objects are in use. Action: Increase the value of the SESSIONS initialization parameter.

ORA-00017 Session requested to set trace event

Cause: The current session was requested to set a trace event by another session. Action: This is used internally; no action is required.

ORA-00001 unique constraint (%s.%s) violated

Cause: An UPDATE or INSERT statement attempted to insert a duplicate key. For Trusted Oracle configured in DBMS MAC mode, you may see this message if a duplicate entry exists at a different level. Action: Either remove the unique restriction or do not insert the key.

ORA-01792: maximum number of columns in a table or view is <>

ORA-01792 appears to be a logical error which means you are attempting to create a table or view with more than 1000 columns or adding columns to an existing table or view resulting in 1000+ columns, however if you are on 12cR1 and above and receiving ORA-01792 from a Select statement then this can be…

ORA-12505 TNS-12505 TNS:listener does not currently know of SID given in connect descriptor

This error is received when the listener received a request to establish a connection to a database or other service but the connect descriptor received by the listener specified a SID for an instance (usually a database instance) that either has not yet dynamically registered with the listener or has not been statically configured for…

ORA-14452 attempt to create, alter or drop an index on temporary table already in use

This error appears when you try to issue a DDL against a global temporary table thats created with “on commit preserve rows” clause.:- create global temporary table TEST (object_id number, object_name varchar2(30)) on commit PRESERVE rows; Such tables get bound to the session with the first insert and then this binding is ONLY removed when…

ORA-12500 TNS-12500 TNS:listener failed to start a dedicated server process

This error appears when the process of starting up a dedicated server process failed and it could be either because the executable could not be found or the environment isn’t set up correctly. Turn on tracing at the ADMIN level and re-execute the operation. Tracing can be set by adding following clause in listener.ora file…

Oracle Auto-Startup Script for Linux

This post is to provide a script to auto-start Oracle Instances on Linux upon server restart. First step would be to configure /etc/oratab file as per your requirement, oratab file is in the following format: <DB NAME>:<ORACLE HOME>:<Y|N> The last letter tells oracle if the database need to restarted or not, so we would change…

row cache lock – Oracle Wait Event

The Row Cache or Data Dictionary Cache is a memory area in the shared pool that holds data dictionary information to reduce physical I/O on the data dictionary tables. The row cache lock is used primarily to serialize changes to the data dictionary and is waited on when a lock on a data dictionary cache…

log file sync – Oracle Wait Event

When a user session commits, the session’s redo information needs to be flushed from memory to the redo logfile to make it permanent. At the time of commit, the user session will post the LGWR to write the log buffer (containing the current unwritten redo, including this session’s redo information) to the redo log file.…