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…

Move Table Online – 12cR2

Until 11gR2 to move a table to different tablespace there were two available methods, first one was ALTER TABLE .. MOVE TABLESPACE but during this the table was locked for DML, thus downtime and the second one was DBMS_REDEFINITION which will allow to create a new table on the desired tablespace and sync the data…

Move Table Partition/Sub-Partition Online – 12cR1

With 12cR1 you can now move table partitions and sub-partitions online. There are lot of reasons for which you might want to move a table partition or sub-partition such as:- Re-cluster data and reduce fragmentation. Move a partition to another tablespace. Modify create-time attributes. Store the data in compressed format using table compression. The problem…

Flashback PDB in Oracle 12cR2

After the introduction of multitenant architecture with Oracle 12cR1, the flashback database feature became irrelevant as it was limited to the root container which resulted in affecting all the PDBs associated with that root container. But with the new release 12cR2, flashback now supports pluggable databases as well. Now we’ll demonstrate how to flashback a…

ORA-12547: TNS:lost contact

This is a quick note to cover ORA-12547: TNS:lost contact error, I would try to include all possible causes of ORA-12547: TNS:lost contact error so that this post itself could assist you in sorting the issue. ORA-12547: TNS:lost contact error could be due to any of the following reasons:- Incorrect permissions on the ORACLE executable.…

Long Identifiers in Oracle Database 12c Release 2

All DBAs & Developers would have always wondered that why Oracle has the identifier limit of 30 bytes whereas other rdbms SQL Server, MySQL etc have much bigger limit. Well honestly even I don’t know that, it has been this way ever since despite multiple request from customers/developers to Oracle to increase the identifier limit,…

SQL Server

This Series of posts would be to cover internals of SQL Server. Once we understand the internals we would start with installation, then basic administration and finally performance tuning & troubleshooting. The list of articles on SQL Server posted on this blog would also be linked below:- Install SQL Server 2017 on Linux SQL Server…