The latest from the MySQL community

MySQL Cluster does an automatic sharding/partitioning to the tables across data nodes, enabling databases to scale horizontally to serve read and write-intensive workloads, but what is the default sharding key used in partitioning the data?
According to the recent update (Oct, 2016) of the MySQL Cluster white paper, primary key is the default sharding key:

By default, sharding is based on hashing of the primary key, which generally leads to a more even distribution of data and queries across the cluster than alternative approaches such as range partitioning.

However, that is not the case in all MySQL Cluster versions so far!
In this post, I’ll do some test cases on MySQL Cluster (of 4 datanodes) to confirm the default sharding key.

Testing on MySQL Cluster 7.2.26 …

Related resources  Sharding MySQL with MySQL Fabric and ProxySQL  MySQL Load Balancing with ProxySQL - an Overview  How to set up read-write split in Galera Cluster using ProxySQL  How ProxySQL adds Failover and Query Control to your MySQL Replication Setup  Two Database Sharding Tools for MySQL

Having too large a (write) workload on a master is dangerous. If the master collapses and a …

Related resources  Sharding MySQL with MySQL Fabric and ProxySQL  MySQL Load Balancing with ProxySQL - an Overview  How to set up read-write split in Galera Cluster using ProxySQL  How ProxySQL adds Failover and Query Control to your MySQL Replication Setup  Two Database Sharding Tools for MySQL

Having too large a (write) workload on a master is dangerous. If the master collapses and a …

We’ve been having a problem with MySQL replication at VividCortex. Replicas periodically tend to fall behind and we couldn’t really figure out how to speed things up. It wasn’t about resources. The replicas have plenty of CPU and I/O available. We’re also using multithreaded replication (a.k.a. MTR) but most of the replication threads were idle.

One thing that we decided to try out was the new LOGICAL_CLOCK parallelization policy introduced in MySQL 5.7.2. Here’s what the MySQL reference manual says about slave-parallel-type:

When using a multi-threaded slave (slave_parallel_workers is greater than 0), this option specifies the policy used to decide which transactions are allowed to execute in …

Today’s blog post is related again to MySQL Group Replication.

By default MySQL Group Replication runs in Single-Primary mode. And it’s the best option and the option you should use.

But sometimes it might happen that in very specific cases you would like to run you MGR Cluster in Multi-Primary mode: writing simultaneously on all the nodes member of the Group.

It’s of course feasible but you need to make some extra verification as not all workload are compatible with this behavior of the cluster.

Requirements

The requirements are the same as those for using MGR in Single-Primary mode:

• InnoDB Storage Engine
• Primary Keys
• IPv4 Network
• Binary Log Active
• Slave Updates Logged
• Binary …

This blog provides a query language type overview.

The idea for this blog originated from some customers asking me questions. When working in a particular field, you often a dedicated vocabulary that makes sense to your peers. It often includes phrases and abbreviations because it’s efficient. It’s no different in the database world. Much of this language might make sense to DBA’s, but it might sound like “voodoo” to people not used to it. The overview below covers the basic types of query languages inside SQL. I hope it clarifies what they mean, how they’re used and how you should interpret them.

DDL (Data Definition Language)

A database schema is a visualization of information. It contains the data structure separated by tables structures, views and anything that contains structure …

Welcome to another post in the series of Percona Live featured tutorial speakers blogs! In these blogs, we’ll highlight some of the tutorial speakers that will be at this year’s Percona Live conference. We’ll also discuss how these tutorials can help you improve your database environment. Make sure to read to the end to get a special Percona Live 2017 registration bonus!

In this Percona Live featured tutorial, we’ll meet Øystein Grøvlen, Senior Principal Software Engineer at Oracle. His tutorial is on How to Analyze and Tune MySQL Queries for Better Performance. SQL query …

In a previous article, Ovais demonstrated how a DDL can render a table blocked from new queries. In another article, Valerii introduced performance_schema.metadata_locks, which is available in MySQL 5.7 and exposes metadata lock details. Given this information, here’s a quick way to troubleshoot metadata locks by creating a stored procedure that can:

• Find out which thread(s) have the metadata lock
• Determine which thread has been waiting for it the longest
• Find other threads waiting for the metadata lock

Setting up …

This year, the MySQL & Friends Devroom will be held on Saturday 4th February 2017.

After having received a lot of submission (the highest amount ever!), with MySQL Community Team, we decided to organize and extra MySQL day that will take place at ICAB Incubator, 4 Rue des Pères Blancs in Brussels (same location as the MySQL Community Dinner). More to come on this day in a future blog post.

So back to the MySQL & Friends Devroom, the Committee high rated the following talks:

Recently I was testing data migration from MSSQL to MySQL using MySQL Workbench. My aim was to include data with all datatype available in MSSQL for migration. In this following blog post will see data migration prerequisites, migration steps and few common errors.

• About MySQL Workbench
• Prerequisite
• DATA SOURCE ODBC Configuration
• Required privileges on MS-SQL DB
• DB Servers Data Types …