Wednesday, 5 February 2025

How does the DBWR process interact with the buffer cache and datafiles?

 The Database Writer (DBWR) process is a crucial background process in Oracle databases that manages the writing of data from the buffer cache to the datafiles. Here's a breakdown of its interaction:   

DB Buffer Cache:

  • The buffer cache is a portion of the System Global Area (SGA) that holds data blocks read from the datafiles. It serves as a temporary storage for frequently accessed data, improving database performance by reducing physical I/O operations.

Tuesday, 4 February 2025

How do parameter files differ between single-instance and RAC environments?

 Parameter Files in Single-Instance vs. RAC: A Deep Dive

Managing Oracle databases involves careful configuration, and a key part of that lies in understanding parameter files. While the basic concepts are similar, there are critical differences in how parameter files behave in single-instance databases compared to Real Application Clusters (RAC) environments. This post will explore these differences with examples, focusing on the shared SPFILE concept in RAC.

What are the advantages of using SPFILE over INIT.ORA?

 An SPFILE (Server Parameter File) is a binary file that stores database initialization parameters in Oracle databases. It was introduced in Oracle 9i as a more robust and manageable alternative to the traditional PFILE (Parameter File), also known as the init.ora file. Here's a breakdown of the advantages of using SPFILE over PFILE:

What is a Parameter File and its Purpose in Oracle Database?

Every Oracle database instance relies on a parameter file to define its fundamental characteristics. Think of it as the database's configuration blueprint. This file dictates everything from memory allocation and database name to control file locations and various other operational settings. Understanding the parameter file is crucial for any DBA or anyone working closely with Oracle databases.   

Monday, 3 February 2025

What is a listener in Oracle Database?

Oracle Listeners: Your Database's Watchman

In the world of Oracle databases, a listener acts like a doorman, managing incoming connection requests from clients. It's a separate process that resides on the database server, patiently waiting for connections. Without a listener, clients can't communicate with the database.

java.lang.AssertionError: No replication server channel, when HTTP port is Disabled

"java.lang.AssertionError: No replication server channel' when HTTP port is Disabled" - this error came when I was trying to setup SSL within Oracle Weblogic. I had created the required keystores (identity.jks & trust.jks) and imported the certificate to these keystores. Post that I added the keystores to all server's (Admin & Managed) configuration and also mapped the certificate alias in SSL tab.

How to use EXPDP to export to multiple locations?

 Efficiently backing up large Oracle databases is crucial for data protection and disaster recovery.  While EXPDP (Export Data Pump) excels at single-location exports, achieving multi-location backups requires a slightly different approach. You might be in a need of exporting a huge schema or some object but you don't have enough storage on single mount point. How to deal with this situation? Well, EXPDP gives you flexibility to export your dump to multiple locations at once. But you must use PARALLEL option to achieve this.