Oracle Instance Memory Usage

How much memory does an Oracle instance actually use? How much does each individual database connection consume? ...

Querying connection information in MongoDB

As with all other database platforms, daily administration and troubleshooting of MongoDB often begins with analyzing ...

Some Fun with MySQL's History List

Why this article? First of all, because I had fun digging in the code. Then, I was reading a lot about the improvements ...

Survey Results: Why Do You Use RMAN Catalog DB for Your Oracle DB Backups?

Mystery Solved: Replication lag in InnoDB

Troubleshooting Replication Lag During XtraBackup While running a backup with XtraBackup against a slave server we ...

SNAPSHOT CONTROLFILE Isn't Just a Backup Copy of a Control File Anymore

Recently, I have troubleshooted failing RMAN backups in 11.2.0.2 RAC environment. The backups failed with an error ...

Oracle VM Manager: OVMAPI_6000E Internal Error: Connection Refused

Quick Update This is just a quick post to share my first 3.1.1 Oracle VM Manager (OVMM) troubleshooting experience. ...

Oracle Database Appliance -- Storage expansion with NFS (dNFS, HCC)

The biggest objection to Oracle Database Appliance (ODA) we hear from customers is about 4TB usable space limit ...

Cursor: Pin S Wait on X in the Top 5 Wait Events

Lately, for some reason, I have started to come across the “cursor: pin S wait on X” wait event in the top 5 wait ...

Locks, Latches, Mutexes, and CPU Usage

I was alerted about a high CPU usage on a client machine. Checking which processes used the most CPU, I found that ...

DUPLICATE from ACTIVE Database Using RMAN, a Step-by-Step Guide

Duplicate using RMAN Recently, I had a request from one of our clients to duplicate a single instance database into a ...

Adaptive Log File Sync: Oracle, Please Don't Do That Again

Disclaimer: Much of what follows is pure speculation on my part. It could be completely wrong, and I'm putting it out ...

T-SQL: Retrieve all users and associated roles for ALL databases

Context A frequent inquiry concerning databases’ security is to retrieve the database role(s) associated with each user ...

Getting GoldenGate Heartbeats Working with SUPPRESSTRIGGERS

Those of you who have seen me present about GoldenGate will know that I recommend using a heartbeat table to monitor ...

Troubleshooting ORA-27090 Async I/O Errors with Systemtap

Last week, I ran into an issue on a high-volume Oracle database where sessions were periodically failing with ORA-27090 ...

Tools That Make Your Work with Oracle VM Easier

After completing your Oracle VM and Oracle VM Manager installation, you are ready to start your friendship with Oracle ...

Disabling Oracle triggers on a per-session basis

Update Jan-2014: I’ve added a note on disabling triggers in Oracle 11.2.0.4 Introduction I recently blogged about an ...

Repost: Oracle Protocol

On 18th May 2003, a man named Ian Redfern published a paper documenting the TNS protocol internals. The paper, entitled ...

Analyzing SQL Server Data File Anatomy

A database is a defined space stored in the system, grouping user objects. This space can be split into several files ...

Exadata Eighth Rack: A Few Thoughts

Oracle CEO Larry Ellison has announced the arrival of a new, smaller member of the Exadata X3 H2M2 family: the eighth ...

My SLOB IO Testing Index

Previous References ALL Pythian blog posts with Post Tag #SLOB My First Experience Running SLOB – Status Update 1 – or ...

Select Statement Generating Redo and Other Mysteries of Exadata

Like many good stories, this one also started with an innocent question from a customer: “I often check “SELECT ...

T-SQL:Generate statements to add TEMPDB datafiles

TEMPDB, is one of SQL server hot-debated topics; there’s always something to say about its sizing, file placement or ...

Debugging IN vs OR Performance in MySQL

I was recently puzzled by the question: “Which query will be faster?” SELECT * FROM table WHERE pk = x OR pk = x1 OR pk ...

Oracle Direct NFS Configuration File Explained

While Oracle tech folks do their best to explain the meaning of not so many DNFS configuration file (oranfstab) ...

Oracle Direct NFS: How to Start

First of all, if you are using NFS to store Oracle database data files, I strongly advise you to enable Oracle Direct ...

Flashback and Forth

A reader of my previous post about Oracle’s Flashback Database posted a comment noting that the Oracle documentation ...

Adding Networks to Exadata: Fun with Policy Routing

The asymmetric routing problem I’ve noticed that Exadata servers are now configured to use Linux policy routing. ...

Introducing the Quarterly Database Patch for Exadata

Introduction Hot on the heels of 11.2.0.3 coming out for Exadata, there’s yet another Exadata patch schedule out: the ...