Sometimes we are not sure if the database design we have created and our site has been using is correct and optimised. We all do have this feeling at times don't we :)


Well, MySQL provides with PROCEDURE ANALYSE() to help us detect inconsistencies in our database design by suggesting for an optimal datatype and data length for columns.

The syntax for using PROCEDURE ANALYSE() is as below:

SELECT ... FROM ... WHERE ... PROCEDURE
ANALYSE([max_elements,[max_memory]])

Ref: …

In this blog post, we’ll discuss the differences between row store and column store databases.

Clients often ask us if they should or could be using columnar databases. For some applications, a columnar database is a great choice; for others, you should stick with the tried and true row-based option.

At a basic level, row stores are great for transaction processing. Column stores are great for highly analytical query models. Row stores have the ability to write data very quickly, whereas a column store is awesome at aggregating large volumes of data for a subset of columns.

One of the benefits of a columnar database is its crazy fast query speeds. In some cases, queries that took minutes or hours are completed in seconds. This makes columnar databases a good choice in a query-heavy …

This is the low-level view of data dictionary language (DDL) operations in the InnoDB storage engine in MySQL 5.6. John Russell gave a more high-level view in his blog post April 2012 Labs Release – Online DDL Improvements. MySQL before the InnoDB Plugin

Traditionally, the MySQL storage engine interface has taken a minimalistic approach to data definition language. The only natively supported operations were CREATE TABLE, DROP TABLE and RENAME TABLE. Consider the following example:

CREATE TABLE t(a INT);
INSERT INTO t VALUES (1),(2),(3);
CREATE INDEX a ON t(a);
DROP TABLE t;

The CREATE INDEX statement would be executed roughly as follows:

CREATE TABLE temp(a INT, INDEX(a));
INSERT INTO temp SELECT * FROM t;
RENAME TABLE t TO temp2;
RENAME TABLE temp TO t;
DROP …

This is the 182nd edition of Log Buffer, the weekly review of database blogs. Make sure to read the whole edition so you do not miss where to submit your SQL limerick!

This week started out with me posting about International Women’s Day, and has me personally attending Confoo (Montreal) which is an excellent conference I hope to return to next year. I learned a lot from confoo, especially the blending nosql and sql session I attended.

This week was also the Hotsos Symposium. …

This Thursday (March 4th, 15:00 UTC - slightly later than usual), Robin Schumacher will present MySQL Column Databases. If you're doing Data Warehouse with your databases this is a must-attend, but it's also interesting to learn what typical other scenarios there are for using column-based storage engines, and how column databases work in the first place.

For MySQL University sessions, point your browser to this page. You need a browser with a working Flash plugin. You may register for a Dimdim account, but you don't have to. (Dimdim is the conferencing system we're using for MySQL University sessions. It provides integrated voice streaming, chat, whiteboard, session recording, …

This Thursday (March 4th, 15:00 UTC - slightly later than usual), Robin Schumacher will present MySQL Column Databases. If you're doing Data Warehouse with your databases this is a must-attend, but it's also interesting to learn what typical other scenarios there are for using column-based storage engines, and how column databases work in the first place.

For MySQL University sessions, point your browser to this page. You need a browser with a working Flash plugin. You may register for a Dimdim account, but you don't have to. (Dimdim is the conferencing system we're using for MySQL University sessions. It provides integrated voice streaming, chat, whiteboard, session recording, …

This Thursday (March 4th, 15:00 UTC - slightly later than usual), Robin Schumacher will present MySQL Column Databases. If you're doing Data Warehouse with your databases this is a must-attend, but it's also interesting to learn what typical other scenarios there are for using column-based storage engines, and how column databases work in the first place.

For MySQL University sessions, point your browser to this page. You need a browser with a working Flash plugin. You may register for a Dimdim account, but you don't have to. (Dimdim is the conferencing system we're using for MySQL University sessions. It provides integrated voice streaming, chat, whiteboard, session recording, …

Today I had to swap 2 columns in one of my MySQL tables. The task, which seems easily accomplishable by a temp variable, proved to be a bit harder to complete. But only just a bit.

Here are my findings:

1. The

   UPDATE swap_test SET x=y, y=x;

   approach doesn't work, as it'll just set both values to y.

   PostgreSQL seems to handle this query differently, as it apparently uses the old values throughout the whole query. [Reference]

2. Here's a method that uses a temporary variable. Thanks to Antony from the comments for the "IS NOT NULL" tweak. Without it, the query works unpredictably. See the table schema at the end of the post. This method doesn't swap the values if one of them is NULL. Use method #3 that doesn't have this limitation. …