Starting with the new release MySQL 5.7 there is support to store JSON documents in a column. During our recent Tech Tour events we got questions about document validation, so ensuring that a JSON document has a certain structure. (Funny. It all started with the idea to be schema-free. Now people seem to need schema enforcement.)
I have two ideas how to implement a schema validation for JSON columns. The first one is by leveraging generated columns together with a foreign key. The second idea is by implementing a trigger. Today I want to focus on the generated columns and foreign keys.
When defining foreign keys with generated columns there are two limitations we need to be aware of:

• Foreign keys require indexes. JSON columns cannot be indexed. We need to leverage other types.
• Only STORED generated columns are supported for foreign keys.

So here is an example of an address table that …

So far, I talked of WMI, CIM, WQL, System.Diagnostics.PerformanceCounterCategory, perf-counter data organization and flavour. Now it's time to look at some performance counters I deem important for my use-case more closely.
Note: List of available Counters for Get-Counter command
Get-Counter -ListSet * | Sort-Object CounterSetName | Format-Table CounterSetName

Basic concepts:I will introduce basic concepts of Processor, Core and CPU now to help you follow the text. Let us use this convention:

• "Processor" is a piece of hardware you connect to a slot on the motherboard.
• "Physical Core" is a physical computing unit built into the "Processor".
• "Virtual Core" is a virtual computing unit built on top of "Physical Core" (i.e. HT is ON).
• "CPU" is a computing unit inside the "Processor", either physical or virtual.

…

Of the different types of clustered MySQL environments, NDB Cluster is among the ones that involves more effort and resource to administer. And unless you are a command line freak, you would want to use a tool that gives you a full view of what is going on in your cluster. 

It is possible to install ClusterControl and monitor your existing MySQL Cluster (NDB). In this blog post, we are going to show you on how to add two existing MySQL Clusters (production and staging) into ClusterControl. 

• ClusterControl: 192.168.55.170
• Cluster #1:
  • Management/API node: mgmd-api1 - 192.168.55.71
  • Management/API node: mgmd-api2 - 192.168.55.72
  • Data node: data1 …

This is a quick post only indirectly related to the series of articles about Docker that I have written recently.

Yesterday I was giving a presentation about Docker in Buenos Aires, and as usual I included a long live demo. Almost all went as expected. There was one step that I tried some time ago, and had always worked well, but when I tried to repeat it on stage, it failed miserably:

• Step 1: run the container

$ docker run  -d --name mybox -e MYSQL_ROOT_PASSWORD=secret mysql/mysql-server …

Among the many New features introduced by MySQL 5.7, we can notice a strong trend towards improving the server security by default. Two features stand out in this respect:

• A password-less root is no longer the default for new installations. Unless you say otherwise, the default installers mysqld --initialize and the deprecated mysql_install_db will generate a random password which the user needs to change.
• The anonymous accounts are no longer created by default. When you start MySQL, you only get the root user (and a new one: read on).

The above features are a great advance not only for security but also for usability. The anonymous users were a continuous source of mismatched connections, …

This Log Buffer Editions picks few blog posts from Oracle, SQL Server and MySQL.

Oracle:

• If you grant the DBA role to a user, Oracle also grants it the UNLIMITED TABLESPACE system privilege. If you then revoke the DBA role from this user, Oracle also revokes its UNLIMITED TABLESPACE system privilege.
• Lost SYSMAN password OEM CC 12gR5.
• How Terminal Emulation Assists Easy Data Management.
• Using EMCLI List Verb …

We’ve had a couple of issues with some of our server infrastructure recently, which have affected portions of our customer base. In this blog post I want to explain what has happened, why, and what we’re doing to correct and prevent it.

I am writing a combined report of these issues because the first one wasn’t fully understood when the second one happened, and because the issues largely have the same contributing factors.

I apologize to our customers who have been impacted. Monitoring is supposed to be more highly available than the monitored systems. I know firsthand how damaging it can be when you can’t access your monitoring data. I take this very seriously and the whole team is working hard to prevent it from recurring.

Summary of Incidents

• On November 15, 2015, from 19:15 until 22:30 Eastern time, some customer data ingest was delayed. Up to 25% of customer environments were affected at …

This is part 2 of our blog on how to troubleshoot Galera cluster - SST errors, and problems with network streaming. In part 1 of the blog, we covered issues ranging from node crashes to clusters that won’t restart, network splits and inconsistent data. Note that the issues described are all examples inspired from real life incidents in production environments.

This is the eighteenth installment in the ‘Become a MySQL DBA’ blog series. Our previous posts in the DBA series include:

• Troubleshooting Galera cluster issues - part 1,
• …

works like charm, thanks

Indexes are usually built by way of a data structure; typically, that structure takes the form of a “tree.” Most commonly, the structure of choice is a B-Tree, which is a hierarchical organization defined by the arrangement and interactions of its nodes.

High in a B-Tree’s hierarchy, you find a root node. Each of the items in that root node points to a collection of items in a child node. This can go on for multiple levels. Eventually, you reach the leaf nodes, where the data itself is stored. Those leaf nodes point back to the rows in the main table. To be technology specific, for instance, in MyISAM, those leaf nodes have offsets in the main data file – the main data file in a MyISAM table is just a sequential collection of rows.

The purpose of an index is to allow a user to very quickly traverse just such a structure – whatever form that structure or algorithm might take – and to locate and examine rows or ranges of …