The latest from the MySQL community

Performance Schema

In many types of database workloads, using a multi-threaded slave from 5.6+ helps improve replication performance. I’ve had a number of users enable this feature, but have not seen anyone ask how each thread is performing. Here’s a quick way with Performance_Schema to measure the amount of multi-threaded slave activity on each thread (after you have already configured MTS on your slave of course ).

First, we need to enable the 

statements

 instruments:

slave1> UPDATE setup_consumers SET ENABLED = 'YES' WHERE NAME LIKE 'events_statements_%';
Query OK, 2 rows affected (0.00 sec)
Rows matched: 3  Changed: 2  Warnings: 0

Next, let’s find the

THREAD_ID

 for our slave workers:

slave1> SELECT THREAD_ID, …

Knowing which privileges a given account has is easy – just issue SHOW GRANTS FOR user@host.  But what about when you need visibility into privileges from the other direction – which accounts can access specific data?  If you’re a DBA – or perform DBA duties, regardless of your title – you may have been asked this question.  It’s an important question to ask in an audit or compliance review – but it can be a difficult question to answer.    This post will walk through how to assess this, but if you’re impatient and need answers to this question immediately, jump to the end – there’s a simple shortcut.

Things to consider

There are a few things you’ll want to consider about the implementation of the MySQL privilege system as you try to sort out who has access to certain data.

Access type

MySQL can restrict privileges based on operations – somebody who has …

We work on data recoveries quite often. In many cases, we recover table structures from the .frm files because there was no backup available. There is already a great blog post by my colleague Miguel Ángel Nieto about how we can recover structures from .frm files using MySQL utilities.

This works pretty well and we prefer to run mysqlfrm with the “–server” option to get all possible information from a .frm file. However, this option expects that MySQL is up and running so that mysqlfrm can spawn a new MySQL instance, and run the structure recovery there.

Recently I came across a tool that makes this job easier. The name of tool is …

IBM POWER 8 is latest generation of the IBM POWER series, and it's a hot one. Above all, for you reading this, POWER 8 is the most Linux friendly so far and IBM really wants you to try this out. Seveal Linux distributions are supporting POWER 8 now, and MariaDB is of course the database of choise. Some cools things with the POWER 8 architecture are the support for CAPI (google for more details) and the fact that POWER 8 machines, due to a vastly superior memory architecture, can grow in memory size, which in general is good news but if you want your own POWER 8, this makes then a bit expensive (although maybe not when you consider the performance you get). IBM has fixed that recently and have announced the LC series of servers which start at $6.600 (see more here: http://www-03.ibm.com/systems/power/hardware/linux-lc.html).

So, whar about MariaDB …

There was some discussion a while back to maybe make MariaDB Server follow the Ubuntu release model, i.e. having a Long Term Release (LTS) and then having a few regular fast releases with a shorter support cycle.

However its good to note that the decision now going forward is to support each and every GA release for a period of five (5) years. However, regular releases will only happen for the latest three (3) GA releases, so at this moment, you are getting updates for MariaDB Server 5.5/10.0/10.1.

Practically, we’ve not seen an update for 5.1/5.2/5.3 since 30 Jan 2013 at the time of this writing. And its clear MariaDB Server 5.5 will have an extended support policy, as it ships in Red Hat Enterprise Linux 7. 

At this time it’s worth …

Google Cloud SQL is a fully managed database service that makes it easy to set-up, maintain, manage, and administer your relational MySQL databases in the cloud. Cloud SQL allows you to focus on your applications rather than administering your databases. Hosted on Google Cloud Platform, Cloud SQL provides a database infrastructure for applications running anywhere.

To evaluate the performance of Google’s Cloud SQL Instances, we ran the tpcc-mysql benchmarking utility with a scale factor of 500 warehouses. The purpose of running tpcc-mysql on each system was to determine the throughput of each instance under varying loads (number of connections or threads).

While the benchmark tests were being run, we took regular snapshots of the following data using MySQL Workbench.

• Number of select transactions executed per second
• Number of insert transactions executed per second
• Number of update …

A Productive Nine Months It’s been around 9 months since we did the first cut of our own MySQL Docker images, and it is time for a bit of an update on where we are in Dockerland these days, and also to talk about some important security related improvements we made to the images lately. […]

When MySQL becomes too slow (or too unstable), temptation usually is to tweak the MySQL configuration file. Indeed, it’s a good place to start. But if you ever looked at the available configuration options, you know things can get messy – MySQL now has over 450 configuration variables for your consideration, that are not classified in any way, and neither of them are included in the stock my.cnf. It’s hard to know where to start!

I’m hoping that this blog post will help you overcome the anxiety of tuning MySQL, whether you’re setting up a new server, or tuning an already running server for better performance.

Don’t do it the way rookies do it

During the last 9 years I’ve spent at Percona working as a MySQL performance and scalability consultant, I found that customers often use the trial and error approach when tuning MySQL configuration: they change a few things and check if it …

Performance Schema has been with us for a while now. Over the years, it has gone a long way from being a curiosity disabled by default to becoming a sophisticated diagnostic tool you may want to enable permanently in your production database.
MySQL 5.7 introduced some exciting Performance Schema features and the first one I'm going to look at is the instrumentation for server memory usage. Have I Got Data For You MySQL 5.7.9 (GA) supports the following memory summary tables (per documentation) that let you look at server memory usage from different angles:

• "memory_summary_by_account_by_event_name" summarizes events for a given account.
• "memory_summary_by_host_by_event_name" summarizes events for a given host.
• "memory_summary_by_thread_by_event_name" summarizes events for a given thread and event name.
…

Support for storing and querying JSON within SQL is progressing for the ANSI/ISO SQL Standard, and for MySQL 5.7. I'll look at what's new, and do some comparisons.

The big picture

The standard document says

The SQL/JSON path language is a query language used by certain SQL operators (JSON_VALUE, JSON_QUERY, JSON_TABLE, and JSON_EXISTS, collectively known as the SQL/JSON query operators) to query JSON text.The SQL/JSON path language is not, strictly speaking, SQL, though it is embedded in these operators within SQL. Lexically and syntactically, the SQL/JSON path language adopts many features of ECMAScript, though it is neither a subset nor a superset of ECMAScript.The semantics of the SQL/JSON path language are primarily SQL semantics.

Here is a chart that shows the JSON-related data types and functions in the standard, and whether a particular DBMS has something with the same name and a similar functionality. …