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 ...

Rails and Database Session Variables

Ruby's ActiveRecord provides a very robust means of manipulating database table structures especially in the context of ...

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 ...

Linux Patching and Oracle: Detect RPM conflicts before they happen

A common scenario in the life of a DBA on a linux server looks something like this: From: Sue-the-sysadamin To:the-dba ...

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 ...

Hashing Algorithm in MySQL PASSWORD()

Investigating the MySQL PASSWORD() Hashing Algorithm Recently we had a question from a customer: what is the hashing ...

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 ...

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 SSPI handshake error

I have seen lots of questions floating in the msdn forums about SSPI Handshake error, the main question is around error ...

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 ...

SQL server: Create missing indexes with unmessing names

If you do any performance tuning, and everyone does, then you’ll come to a point where you want to know if your tables ...

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 ...

My SLOB IO Testing Index

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

Once again about innodb-concurrency-tickets

I had to refresh my knowledge on how InnoDB threads queue works the other day when debugging activity spikes on one of ...

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 ...

RMAN duplicate in details

Its all started from the question on communities.oracle.com An “enhancement” in 11.2 prevents RMAN duplicating non ...

Exadata Patching Overview

Introduction Hello everyone ! For my first time posting here on the Pythian Blog, I would like to share some of my ...

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 ...

Exadata Memory Expansion Kit

It’s always interesting to dig into the spec sheets for Exadata hardware, especially when those "minor" details like ...

Flashback and Forth

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

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 ...