ORA-12502 TNS-12502 TNS:listener received no CONNECT_DATA from client

TNS:listener received no CONNECT_DATA from clientCause: No CONNECT_DATA was passed to the listener.Action: Check that the service name resolved from TNSNAMES.ORA has the CONNECT_DATA component of the connect descriptor. Below is the sample entry of tnsnames.ora:- #When using SERVICE_NAME in CONNECT_DATA componentorcl.example.com = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = myserver.example.com)(PORT =…

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…

Library Cache Pin – Oracle Wait Event

Library cache pins are used to manage library cache concurrency. Pinning an object causes the heaps to be loaded into memory (if not already loaded). PINS can be acquired in NULL, SHARE or EXCLUSIVE modes and can be considered like a special form of lock. A wait for a “library cache pin” implies some other…

Library Cache lock – Oracle Wait Event

The library cache lock controls the concurrency between clients of the library cache by acquiring a lock on the object handle so that either: One client can prevent other clients from accessing the same object The client can maintain a dependency for a long time (no other client can change the object). This lock is…

12c New Features – Invisible Columns

There can be several situations where you want to test the impact of dropping a column from a table, till 11gR2 Oracle provided an option to mark a column as UNUSED before dropping a column, and do ALTER TABLE … DROP UNUSED COLUMNS at a later time but marking a column UNUSED is a irreversible…