Essential Oracle Database Keywords for DBAs - Part 2

When you are preparing for an Oracle DBA interview — or troubleshooting a production issue at 2 AM — definitions alone are not enough. You need clarity. You need context. And most importantly, you need to understand how Oracle behaves under pressure.

When Oracle Uses PGA Instead of SGA for Large Table Scans

Most Oracle DBAs learn early in their careers that the System Global Area (SGA) is the primary memory structure used for caching data blocks. The assumption is simple: data blocks are read from disk, placed in the buffer cache, and reused by future sessions.

However, that assumption doesn’t always hold true in production.

In many real-world workloads , especially analytics queries, reporting jobs, or large batch processing-- . Oracle intentionally bypasses the buffer cache and reads data directly into the Program Global Area (PGA). This behaviour surprises many DBAs when they notice unusual wait events like direct path read, or when frequently queried tables seem to generate repeated disk I/O.

Adding an Instance to Oracle RAC: Step-by-Step Guide for DBAs

 Expanding your Oracle Real Application Clusters (RAC) database by adding a new instance can be intimidating, especially if you want to ensure zero downtime and seamless integration. Whether you're introducing a new node or simply adding an instance to an existing one, the process involves careful planning, configuration, and execution. In this guide, we’ll walk you through every step, from preparing the environment to verifying the new instance’s operation. By the end of this article, you will have a clear understanding of both DBCA and SRVCTL methods for adding instances, best practices for shared storage and network setup, and tips to avoid common pitfalls.

Oracle Utilities for DBAs: Complete Guide to Essential Tools

 Managing an Oracle Database efficiently requires mastering a variety of utilities designed for administration, data movement, performance tuning, and troubleshooting. Whether you’re performing backups, moving data, monitoring performance, or tuning SQL queries, Oracle provides tools to streamline every task. In this guide, we’ll cover the most commonly used Oracle utilities, grouped by functionality, with practical examples and best practices for real-world DBA scenarios.

Understanding Oracle 19c DML Internals for OLTP Performance

For Oracle DBAs managing high-volume OLTP (Online Transaction Processing) systems, understanding how core DML (Data Manipulation Language) operations function under the hood is essential. SELECT, INSERT, UPDATE, and DELETE statements are the backbone of any database, but their internal mechanics—parsing, execution, undo/redo generation, buffer cache interactions, and transaction control—can significantly impact system performance.