Posts Categorized: Technical Blog

Designing Index to Eliminate Sorting

Using algorithm described in “Relational Database Index Design and the Optimizers by Tapio Lahdenmaki and Mike Leach”, I quickly came up with two indexes and while first one looked fine, I was really confused by the second one for the elimination of the sort. Let me show an example, not copy one from the book, but rather show a test I did with MySQL.

Database Migration to ASM

I was working on a task of 10g Active-Passive cluster design where I was supposed to migrate a database to ASM from conventional filesystem. So I thought of writing this blog. Here are the steps which I followed to move the database to ASM and then created a spfile in ASM diskgroup in the end.

Using KateSQL to connect to an Oracle database in Kate

Among the features announced with the release of version 4.6 of the KDE Software Compilation is KateSQL, a SQL Query plugin for the Kate text editor. It leverages the Qt SQL module, enabling connections to most types of databases, and includes support for MySQL and SQLite. In this post I’ll show you how to get it to connect to Oracle databases.

InnoDB error: Total number of locks exceeds the lock table size

Recently, one of our customers had a problem with one of their replication slaves where a sql statement gave an error while executing on the slave which was executed successfully on the Master server. The slave stopped with the error. We found the main difference in MySQL configuration between Master and Slave was the amount of memory allocated to innodb_buffer_pool_size because Slave was running several MySQL instances that were used for backup purposes. We need to increase the memory of innodb_buffer_pool_size variable where the locks table can fit in the configuration file and restart the database. This should fix the problem.

ASCII Interface for Games

The best way to get a feel for a module is to work with it, I decided to try my hand at a small, unassuming maze game. For the maze creation itself, I used Games::Maze, and with that out of the way, the resulting program turned out to be quite simple, have a look.

Replication Issues: Never purge logs before slave catches them!!

A customer contacted us regarding a problem with one of their replication servers. We found they had deleted some binary logs from the master and relay logs from the slave to release space. It is not a good idea to delete logs that aren’t cached by the slave, in case they are needed. At least keep relay logs in slave to keep the replication working.

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