I have merged a debugger for MySQL/MariaDB stored procedures and functions into our GUI client and posted the source and binaries on github. It allows breakpoint, clear, continue, next, skip, step, tbreakpoint, and variable displays. Features which are rare or missing in other debuggers include:
its current platform is Linux;
it allows breakpoints on functions which are invoked within SQL statements;
it never changes existing stored procedures or functions;
it is integrated with a general GUI client;
it allows commands like gdb and allows menu items / shortcut keys like ddd;
it is available on github as C++ source with GPL licence.

It's alpha and it's fragile but it works. Here is a demo.

Start the client and connect to a running server, as root. Actually the required privileges are merely for creation of certain objects and SUPER, but …

Technical conferences are flooded with visual [mis]representations of a particular product's performance, compression, cost effectiveness, micro-transactions per flux-capacitor, or whatever two-axis comparison someone dreams up. Lets be honest, benchmarketers like to believe we all suffer from innumeracy.

The Merriam-Webster dictionary defines innumeracy as follows:
innumeracy (noun): marked by an ignorance of mathematics and the scientific approach Mark Callaghan has been a long time advocate of explaining benchmark results, but that's not the point of the bar chart. Oh no, the bar chart only exists to catch your eye and …

From time to time people wonder how to implement roles in MySQL. This can be useful for companies having to deal with many user accounts or for companies with tight security requirements (PCI or HIPAA for instance). Roles do not exist in regular MySQL but here is an example on how to emulate them using Percona Server, the PAM plugin and proxy users.

The goal

Say we have 2 databases: db1 and db2, and we want to be able to create 3 roles:

• db1_dev: can read and write on db1 only.
• db2_dev: can read and write on db2 only.
• stats: can read on db1 and db2

For each role, we will create one user: joe (db1_dev), mike (db2_dev) and tom (stats).

Setting up the Percona PAM plugin

The Percona PAM plugin is distributed with Percona Server 5.5 and 5.6. I will be using …

By courtesy of Intel we had access to a very large cluster of Intel servers for a few
weeks. We took the opportunity to see the improvements of the Intel
servers in the new Haswell implementation on the Intel Xeon chips. We also took
the opportunity to see how far we can now scale flexAsynch, the NoSQL benchmark
we've developed for testing MySQL Cluster.

Last time we tested we were using MySQL Cluster 7.2 and the main bottleneck
then was that the API nodes could not push through more than around 300k reads
per second and we have a limit of up to 255 nodes in total. This meant that we
were able to reach a bit more than 70M reads per second using MySQL Cluster 7.2.

In MySQL Cluster 7.3 we improved the handling of thread contention in the NDB API
which means that we are now able to process much more traffic per API node.
In MySQL Cluster 7.4 we also improved …

Some weeks back I helped a customer lower time to bulk-load data into MySQL, they where at the time using a MySQL dumpfile (containing SQL statements) to populate their tables during nightly jobs.

By using LOAD DATA INFILE command and creating secondary indexes after bulk-load of data load time went down by a factor of almost 2x.

My test environment:
DB: MySQL 5.6.23
OS: Ubuntu 14.04
HW: My Toshiba Portege laptop with 2 cores and SSD disk

Commands/tables used in tests:

I created a file …

The other day we were doing some peer review on a schema change at VividCortex and the topic of character set, column length, and the potential downsides of using utf8 came up. I knew from experience that there are some hidden gotchas with this, and usually I’ll just say a couple words and send a link with further reading. But Google turned up nothing, so I am writing this post to try to help fix that.

TL;DR version is that when MySQL can’t use an index for operations such as ORDER BY, it may allocate fixed-length memory buffers large enough to hold the worst-case values, and the same might apply to temporary tables on disk. This can be seen in EXPLAIN as “Using filesort; using temporary” and similar. And when this happens, you might end up making MySQL do gigabytes worth of work to finish a query on a table that’s only a fraction of that size.

Let’s see why this can happen.

The Theory of UTF8

In …

  Packt Publishing started a Free Learning Campaign by providing a free ebook everyday till 6th March 2015. How ? Follow this link: http://bit.ly/1DoRno5

[…] I am connecting following Andrews advice: Stackoverflow Link Also, Monitoring and Managing […]

This Log Buffer Edition makes it way through the realms of Oracle, SQL Server and MySQL and brings you some of the blog posts.

Oracle:

Introducing Oracle Big Data Discovery Part 3: Data Exploration and Visualization

FULL and NO_INDEX Hints

Base64 Encode / Decode with Python (or WebLogic Scripting Tool) by Frank Munz

Why I’m Excited About Oracle Integration Cloud Service – New Video

Reminder: …

For years, MySQL replication used to be based on binary log events - all a slave knew was the exact event and the exact position it just read from the master. Any single transaction from a master may have ended in different binary logs, and in different positions in these logs. It was a simple solution that came with limitations - more complex topology changes could require an admin to stop replication on the hosts involved. Or these changes could cause some other issues, e.g., a slave couldn’t be moved down the replication chain without time-consuming rebuild process (we couldn’t easily change replication from A -> B -> C to A -> C -> B without stopping replication on both B and C). We’ve all had to work around these limitations while dreaming about a global transaction identifier.

GTID was introduced along with MySQL 5.6, and brought along some major changes in the way MySQL operates. First of all, every transaction has …