I was surprised by the recent announcement that MySQL are going to start to conceal the hidden function calls in their C connector. Surprised because although this is great news I had expected them to do this years ago. Working for HP's Advanced Technology Group I realise I take such things for granted. For this blog post I'm going to talk about why it is important and how to do it.

So, when you create a dynamic library in C the default thing that happens is every function call in that library effectively becomes a potential API call. Whether you document every single function or not to make it official API is up to you but I suspect in 99.99% of cases there are private functions you don't want users to mess with. Additionally holding the symbol information for every function so that you can link your application to it takes a …

Wed, 2015-01-21 18:27guillaumelefranc

If you are a DBA or system administrator, you should already be familiar with Percona Xtrabackup, the free hot backup tool for MariaDB and MySQL, and you probably use it to take onsite backups of your production databases.

But what if the backup server is inaccessible because of an outage, or the data has been corrupted? Offsite backups should also be part of a complete disaster recovery strategy.

Amazon Web Services is one of the most popular cloud services providers, and they developed Amazon S3 (Simple Storage Service) initially to backup their own Oracle databases. S3 is now used by many companies to store objects such as website statics, but it’s still a very popular solution for storing online backups: it’s cheap, reliable and easy to setup.

In this article we’ll see how to store securely our MariaDB+Xtrabackup backups in the cloud, using encryption and …

As many know, I have been working within the Espresso team at LinkedIn since 2012. Espresso is a schema-ed document store built upon MySQL.

Introducing Espresso - LinkedIn's hot new distributed document store

We eventually hope to open-source a version of Espresso which doesn't use LinkedIn's internal proprietary APIs.

About one and a half years ago we created MySQL StatsD to keep get insights of any MySQL server using a local daemon that frequently queries the MySQL server and pushes its data to StatsD locally. In the past year we have seen the usage of the MySQL StatsD project increase and more and more […]

The post MySQL StatsD release 0.1.3 appeared first on Spil Games Engineering.

We plan to hide (not export) the symbols of the SSL library used by the MySQL client library. As step one in that effort, we plan to hide all of the non-documented symbols because we want to stop polluting the MySQL client program’s namespace.

Consider a requirement where there the OpenSSL and MySQL client library functions are both used directly to generate a binary. If the order of linking used is 1. MySQL client library (i.e libmysqlclient) and then 2. OpenSSL library (i.e libcrypto), then using the created binary will result in a crash.

The Reason why it will crash is as follows: The libmysqlclient library already has the built-in yaSSL library and has exported its symbols. The yaSSL and OpenSSL libraries share some of the same symbol names, so the executable which is prepared in the above said order, will resolve the OpenSSL symbols indirectly using the libmysqlclient library (yaSSL) rather than using …

Mydumper is known as the faster (much faster) mysqldump alternative. So, if you take a logical backup you will choose Mydumper instead of mysqldump. But what about the restore? Well, who needs to restore a logical backup? It takes ages! Even with Myloader. But this could change just a bit if we are able to take advantage of Fast Index Creation.

As you probably know, Mydumper and mysqldump export the struct of a table, with all the indexes and the constraints, and of course, the data. Then, Myloader and MySQL import the struct of the table and import the data. The most important difference is that you can configure Myloader to import the data using a certain amount of threads. The import steps are:

1. Create the complete struct of the table
2. Import the data

When you execute Myloader, internally it first creates the tables executing the “-schema.sql” files and then takes all the filenames …

A Percona Xtradb (Galera) Cluster node may fail to join it due to many possible mistakes causing SST to fail. It could be a configuration item or purely setup requirement. In this article we will be troubleshooting step by step the SST issues faced.

The post Debugging Percona Xtradb (Galera) Cluster node startup / SST errors first appeared on Change Is Inevitable.

At VividCortex, security is a top priority. Leading companies such as Zappos, Dyn, and Etsy use our cloud-based database performance management service to monitor MySQL in production. We have designed for performance, isolation, and security from the start.

Even small decisions can make a big difference. One of those micro-decisions is making all of our APIs return a top-level object in JSON, never a top-level array. This is to avoid an old, obscure, unlikely, but still possible JSON security vulnerability.

If you have never heard of JSON security vulnerabilities, you should go read Anatomy of a subtle JSON vulnerability before continuing.

Now that you’ve read that, you know a lot more than most people about JSON and security! Although modern browsers have fixed the underlying vulnerability, older browsers …

It is a common database pattern to increment an INT column when an event happens, such as a download. Early last year at GitHub we started encountering issues with slow UPDATES to these types of counters.

You can go far with this pattern until bursts of these types of events happen in parallel and you experience contention on a single row. When multiple transactions are trying to update the counter you are essentially forcing these transactions to run serially which is bad for concurrency.

You can see here a dramatic increase in query time when a burst like this occurred:

<img src=”/images/burst.png” height=“200px” width=”725px” />

To avoid problems like this we had to do this kind of counting differently. We decided on using a separate table with a schema similar to this:

CREATE TABLE `slotted_counters` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `record_type` int(11) NOT NULL, …

As a MySQL DBA/consultant, it is part of my job to decode the MySQL binary logs – and there are a number of reasons for doing that. In this post, I’ll explain how you can get the important information about your write workload using MySQL row-based binary logs and a simple awk script.

First, it is important to understand that row-based binary logs contain the actual changes done by a query. For example, if I run a delete query against a table, the binary log will contain the rows that were deleted. MySQL provides the mysqlbinlog utility to decode the events stored in MySQL binary logs. You can read more about mysqlbinlog in detail in the reference manual here.

The following example illustrates how mysqlbinlog displays row events that specify data modifications. These correspond to events with the WRITE_ROWS_EVENT, UPDATE_ROWS_EVENT, …