In a world where new data processing languages appear every day, it can be helpful to have tutorials explaining language characteristics in detail from the ground up.  This blog post is not such a tutorial.   It also isn’t a tutorial on getting started with MySQL or Hadoop, nor is it a list of best practices for the various languages I’ll reference here – there are bound to be better ways to accomplish certain tasks, and where a choice was required, I’ve emphasized clarity and readability over performance.  Finally, this isn’t meant to be a quickstart for SQL experts to access Hadoop – there are a number of SQL interfaces to Hadoop such as Impala or Hive that make Hadoop incredibly accessible to those with existing SQL skills.

Instead, this post is a pale equivalent of the …

This blog post is an update to our last post discussing database compression methods, and how they stack up against each other. 

When Vadim and I wrote about Evaluating Database Compression Methods last month, we claimed that evaluating database compression algorithms was easy these days because there are ready-to-use benchmark suites such as lzbench.

As easy as it was to do an evaluation with this tool, it turned out it was also easy to make a mistake. Due to a bug in the benchmark we got incorrect results for the LZ4 …

Starting with MySQL 5.7 we introduced the Query Rewrite Plugin. That tool is really useful for changing queries. Of course the best location to modify the query is the source code of the application, but this is not always possible. Either the application is not under your control or queries are generated from a framework like Hibernate and sometimes it is hard to change the query generation.
If you are interested in details about the Query Rewrite Plugin, I recommend this blogpost from the MySQL Engineering: http://mysqlserverteam.com/the-query-rewrite-plugins/
Recently I was asked how this works in replication environments. Which query goes into the binlog?

If you are using the Rewriter plugin that comes with MySQL 5.7, the answer is easy: This plugin only supports rewriting SELECT queries. SELECT queries don't get into the binlog …

Interesting developments in the MySQL world – it can now be used as a document store and you can query the database using JavaScript instead of SQL (via the MySQL Shell). There is also a new X Plugin (see: mysql-5.7.12/rapid/) (which now makes use of protocol buffers (see: mysql-5.7.12/extra/protobuf/)). I will agree, this is more than just a maintenance release.

Do get started playing with MySQL Shell. If you’re using the yum repository, remember to ensure you have …

If you have been following our multi-part blog-post series around MySQL 5.7.12 so far you have heard on term a lot: “X”. So what does X stand for? A very good question, let’s see if Part 3 of the blog-post series on the MySQL Document Store will help you finding more about that.…

The X Protocol

For the MySQL Document Store we developed a new protocol to lay out a solid foundation for the features we’ll implement over the next years.

Building a Protocol with Async APIs in mind

Asynchronous APIs are all about executing other work while a task gets blocked.

…

Based on messages, we create mysql replication platforms , using async message to build strong distributed subscription system.

read this PDF : http://www.vmcd.org/docs/MySQL_async_message.pdf

Percona Live is a Christmas in MySQL world. It’s time when all friends and family gather over a glass of beer. Everyone is talking about achievements of the last year and make New Year resolutions for a next one.

There will be two talks from TwinDB this year. One is about data recovery and one – about backups.

The data recovery talk is a kind of traditional talk. I will briefly cover InnoDB files format so you know where to look for data. I will show how to recover data from two most popular accidents: InnoDB tablespace corruption and DROP TABLE or DROP DATABASE. Data recovery is impossible without table structure recovery. I will show how to get the structure from an .frm file or from InnoDB dictionary (think of DROP TABLE when the .frm file is gone). We made a drastic improvement in user …

In this blog post, we will discuss how to deal with jumbo chunks in MongoDB.

You are a MongoDB DBA, and your first task of the day is to remove a shard from your cluster. It sounds scary at first, but you know it is pretty easy. You can do it with a simple command:

db.runCommand( { removeShard: "server1_set6" } )

MongoDB then does its magic. It finds the chunks and databases and balances them across all other servers. You can go to sleep without any worry.

The next morning when you wake up, you check the status of that particular shard and you find the process is stuck:

"msg" : "draining ongoing",
"state" : "ongoing",
"remaining" : {
"chunks" : NumberLong(3),
"dbs" : NumberLong(0)

There are three chunks that for some reason haven’t been migrated, so the

removeShard

In this blog post we’ll discuss a caveat when downloading MariaDB MaxScale binaries.

Following the previous performance results in my last two posts on sysbench and primary keys (https://www.percona.com/blog/2016/04/07/mysql-5-7-sysbench-oltp-read-results-really-faster/ and https://www.percona.com/blog/2016/03/28/mysql-5-7-primary-key-lookup-results-is-it-really-faster/), I wanted to measure overhead from proxies servers like ProxySQL and MaxScale.

Unfortunately, I found that MaxScale binaries are not available without registering on the …