Oracle DBA

  The  shared pool  caches various types of program data. For example, the shared pool stores parsed SQL, PL/SQL code, system parameters, and  data dictionary  information. The shared pool is involved in almost every operation that occurs in the database. For example, if a user executes a SQL statement, then Oracle Database accesses the shared pool. This section includes the following topics: Data Dictionary: The Data Dictionary Cache stores metadata about the database schema, such as information about tables, columns, indexes, and constraints. This cache helps speed up queries and operations by providing quick access to this metadata. The data dictionary is a collection of database tables and views containing reference information about the database, its structures, and its users. Oracle Database accesses the data dictionary frequently during SQL statement parsing. The data dictionary is accessed so often by Oracle Database that the following special memory loc...

  Fixing INS-40719: SCAN IP Already Assigned – Oracle Grid Infrastructure Installation Error When installing  Oracle Grid Infrastructure 19c  for RAC, one of the most common issues beginners face is the SCAN configuration error: INS-40719: IP address configured for Single Client Access Name (SCAN) is already assigned to another system. This error stops the installation unless you fix the SCAN IPs. In this blog, we explain  why it happens ,  how to solve it , and how to properly configure your  /etc/hosts  file for RAC. Why This Error Happens (INS-40719) Oracle requires  3 dedicated SCAN IPs  for the RAC cluster. These IPs must be: Not assigned to any machine Not pingable Reserved exclusively for SCAN If you enter SCAN IPs that are already used by VirtualBox, a VM, or any other device, the installer immediately throws the error. Solution — Use New Unused SCAN IPs You must select  three fresh, unused IP addresses  from your network ra...

  How to Start and Stop Oracle Data Guard 19c (Step-by-Step Guide) Oracle Data Guard is one of the most reliable solutions for  data protection, disaster recovery, and high availability . As a DBA, knowing how to properly  start and stop the Data Guard (Standby) environment  is essential for maintenance, patching, and troubleshooting. This guide provides a clear and easy-to-follow explanation of how to gracefully  stop  and  start  your Oracle 19c Data Guard standby database. How to Stop the Standby (DR) Database Stopping the standby database involves three main tasks: 1️⃣ Stop Listener 2️⃣ Cancel Managed Recovery 3️⃣ Shutdown Database Let’s go through them one by one. 1. Stop the Listener Use the  lsnrctl  command: lsnrctl stop <listener_name> Replace  <listener_name>  with your actual listener name (often  LISTENER  or a custom name). Stopping the listener ensures that new database connections do not occ...