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Continue reading →: Does Your Storage Respond Fast Enough?
The response time of the storage subsystem is critical to overall Oracle database performance. Assessing storage responsiveness can be challenging for DBAs who lack direct access to the Operating System and cannot utilize traditional tools like iostat or sar. Oracle provides a critical metric for this purpose: Average Synchronous Single-Block…
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Continue reading →: Detecting CPU-Noisy Neighbors in Oracle
In Oracle environments, CPU-noisy neighbors are non-Oracle processes that consume significant CPU resources and reduce the CPU available to the database. CPU-noisy neighbors can be detect by comparing total OS CPU usage with Oracle CPU usage. If the gap between is huge, it strongly suggests the presence of a CPU-noisy…
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Continue reading →: Step-by-Step: Installing Oracle 26ai RAC Database on Linux Using VMware
Conceptual Architecture A conceptual architecture diagram of Oracle RAC is as follows: The biggest obstacles to building a private RAC test environments is the requirement for shared storage. Traditionally, this necessitates expensive SAN hardware.However, by leveraging VMware ESXi’s advanced disk attributes, specifically the multi-writer flag, we can simulate a professional…
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Continue reading →: Step-by-Step: Installing Oracle 26ai via RPM and Creating Databases
Installing Oracle Database on Linux using RPM packages significantly reduces deployment complexity. Many intricate configuration steps are handled automatically during the package installation. This article demonstrates the process of installing Oracle 26ai using the RPM method on RHEL 9. 1. Linux Operating System Preparation To resolve dependency issues on RHEL,…
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Continue reading →: Why Incremental Backups Can Be Deadlier Than Full Backups
A common assumption in Oracle database administration is that incremental backups are inherently lighter than full backups. However, a recent real-wold case revealed a counterintuitive result.
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Continue reading →: Troubleshooting ORA-01152: When Datafiles are “From the Future”
The ORA-01152 error is a common headache for DBAs, particularly after a database restore operation or when recovering from a backup control file. It essentially tells you that your database files are “newer” than your control file expects. Below is a guide on how to diagnose the issue and resolve…
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Continue reading →: Evaluating Storage Performance by AWR Snapshot Raw Data
As a DBA, having a clear understanding of your storage performance is essential to correctly judge overall database behavior. However, in many enterprises, DBAs do not have OS-level access, so they cannot use tools like iostat or sar. Fortunately, Oracle’s AWR Snapshot Raw Data retains historical I/O performance metrics that…
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Continue reading →: Oracle AWR Case Study: Diagnosing ‘enq: TX – row lock contention’
In a busy and healthy database environment, it is unavoidable that multiple sessions will attempt to modify the same row or set of rows simultaneously. This leads to situations where one session must wait for another to finish before proceeding, resulting in the “enq: TX – row lock contention” wait…
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Continue reading →: Oracle AWR Case Study: Pinpointing When the Execution Plan Flip Occurred
One day, users angrily complained that the Oracle database had suddenly become unbearably slow. They could feel the lag but had no idea when the slowdown actually started. The Standout Troublemaker Below is the “SQL Statistics” section from the latest AWR report: The top SQL consumed more than 99% of…
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Continue reading →: How Oracle Calculates the Number of Sessions in the AWR Report
At the top of every Oracle AWR report, there’s an important metric called “Sessions”, which represents the number of sessions at the time each snapshot (Snap ID) is being taken. This value comes from the logons current statistic in the DBA_HIST_SYSSTAT table. Let’s take a closer look at how Oracle…
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