September 20, 2014

How to monitor ALTER TABLE progress in MySQL

While working on a recent support issue as a Percona Support Engineer,  I got one question from a customer asking how to monitor ALTER TABLE progress. Actually, for MySQL 5.5 and prior versions, it’s quite difficult to ALTER the table in a running production environment especially for large tables (with millions records). Because it will rebuild and lock the table […]

How to recover table structure from .frm files with MySQL Utilities

Table structures are stored in .frm files and in the InnoDB Data Dictionary. Sometimes, usually in data recovery issues, we need to recover those structures to be able to find the lost data or just to recreate the tables. There are different ways to do it and we’ve already written about it in this blog. […]

Understanding the maximum number of columns in a MySQL table

This post was initially going to be two sets of polls: “What is the maximum number of columns in MySQL?” and “What is the minimum maximum number of columns in MySQL?”. Before you read on, ponder those questions and come up with your own answers… and see if you’re right or can prove me wrong! […]

InnoDB Full-text Search in MySQL 5.6: Part 2, The Queries!

This is part 2 in a 3 part series. In part 1, we took a quick look at some initial configuration of InnoDB full-text search and discovered a little bit of quirky behavior; here, we are going to run some queries and compare the result sets. Our hope is that the one of two things […]

Data compression in InnoDB for text and blob fields

Have you wanted to compress only certain types of columns in a table while leaving other columns uncompressed? While working on a customer case this week I saw an interesting problem where a table had many heavily utilized TEXT fields with some read queries exceeding 500MB (!!), and stored in a 100GB table. In this […]

The relationship between Innodb Log checkpointing and dirty Buffer pool pages

This is a time-honored topic, and there’s no shortage of articles on the topic on this blog. I wanted to write a post trying to condense and clarify those posts, as it has taken me a while to really understand this relationship. Some basic facts Most of us know that writing into Innodb updates buffer […]

Hijacking Innodb Foreign Keys

I guess I’m first to post in 2012 so Happy New Year all blog readers ! Now back to HardCore MySQL business – foreign Keys. MySQL supported Foreign Keys for Innodb for many years, yet rudimentary support initially added in MySQL 3.23.44 have not been improved in new releases as much as I’d like. We […]

Helgrinding MySQL with InnoDB for Synchronisation Errors, Fun and Profit

It is no secret that bugs related to multithreading–deadlocks, data races, starvations etc–have a big impact on application’s stability and are at the same time hard to find due to their nondeterministic nature.  Any tool that makes finding such bugs easier, preferably before anybody is aware of their existence, is very welcome.

Recovering CREATE TABLE statement from .frm file

So lets say you have .frm file for the table and you need to recover CREATE TABLE statement for this table. In particular when we do Innodb Recovery we often get .frm files and some mess in the Innodb tablespace from which we have to get data from. Of course we could relay on old […]