To resolve a critical regression, Percona announces the release of Percona XtraDB Cluster 5.7.23-31.31.2 on October 2, 2018 Binaries are available from the downloads section or from our software repositories.

This release resolves a critical regression in Galera’s wsrep library and supersedes 5.7.23-31.31

Percona XtraDB Cluster 5.7.23-31.31.2 is now the current release, based on the following:

• Percona Server 5.7.23-23
• Galera …

Your database cluster contains your most business-critical data. The slave nodes must be online, healthy and in sync with the master in order to be viable failover candidates.

This means keeping a close watch on the health of the databases nodes from many perspectives, from ensuring sufficient disk space to testing that replication traffic is flowing.

A robust monitoring setup is essential for cluster health and viability – if your replicator goes offline and you do not know about it, then that slave becomes effectively useless because it has stale data.

Big Brother is Watching You! The Power of Nagios

Even while you sleep, your servers are busy, and you simply cannot keep watch all the time. Now, more than ever, with global deployments, it is literally impossible to watch everything all the time.

Enter Nagios, you best big brother ever. As a long-time player in the monitoring market, Nagios has both …

We saw in the previous post that MySQL likes memory. We also saw how to perform operating system checks and some configuration changes for Swap and NUMA.

Today, we will check what MySQL server can tell us about its memory usage.

Introduced in MySQL 5.7 and enabled by default in MySQL 8.0, the Performance_Schema‘s Memory instrumentation allows us to have a better overview of what MySQL is allocating and why.

Let’s check on our MySQL server using SYS:

Pay attention that there is a bug related to how InnoDB Buffer Pool statistics are accounted in Performance_Schema. This is fixed in 8.0.13. …

Tweet

There are various ways to shutdown MySQL. The traditional cross platform method is to use the shutdown command in the mysqladmin client. One drawback is that it requires shell access; another is that it cannot start MySQL again automatically. There are platform specific options that can perform a restart such as using systemctl on Linux or install MySQL as a service on Microsoft Windows. What I will look at here though is the built in support for stopping and restarting MySQL using SQL statements.

Photo by …

In our work, We used to get a lot of requirements for replicating data from one data source to another.Previously I wrote replication from MySQL to Red-shift.

In this blog I am going to explain about replicating the data from MySQL to Oracle using Tungsten replicator.

1.0. Tungsten Replicator :

It is an open source replication engine supports data extract from MySQL, MySQL Variants such as RDS, Percona Server, MariaDB and Oracle and allows the data extracted to be applied on other data sources such as Vertica, Cassandra, Redshift etc.

Tungsten Replicator includes support for parallel replication, and advanced topologies such as fan-in and multi-master, and can be used efficiently in cross-site deployments.

1.1.0. Architecture :

There are three major …

Recently I ran across a prominent PHP Developer who incorrectly claimed that only PDO allows binding values to variables for prepared statements.  A lot of developer use prepared statements to reduce the potential of SQL Injection and it is a good first step.  But there are some features that you do no kno

What is a Prepared Statement?
The MySQL Manual states The MySQL database supports prepared statements. A prepared statement or a parameterized statement is used to execute the same statement repeatedly with high efficiency.

So far, so good. Well there is also a performance issue to consider too.  From the same source The prepared statement execution consists of two stages: prepare and execute. At the prepare stage a statement template is sent to the database server. The server performs a syntax check and initializes server internal resources for later use.

…

Following my post from a year ago https://www.percona.com/blog/2017/07/06/clickhouse-one-year/, I wanted to review what happened in ClickHouse during this year.
There is indeed some interesting news to share.

1. ClickHouse in DB-Engines Ranking. It did not quite get into the top 100, but the gain from position 174 to 106 is still impressive. Its DB-Engines Ranking score tripled from 0.54 last September to 1.57 this September

And indeed, in my conversation with customers and partners, the narrative has changed from: “ClickHouse, what is …

I personally believe that the best way to deliver a complicated message to an audience, is by using a simple example. So in this post, I chose to demonstrate how to obtain insights from MySQL's EXPLAIN output, by using a simple SQL query which fetches data from StackOverflow's publicly available dataset.

The EXPLAIN command provides information about how MySQL executes queries. EXPLAIN can work with SELECT, DELETE, INSERT, REPLACE, and UPDATE statements.

We'll first analyze the original query, then attempt to optimize the query and look into the optimized query's execution plan to see what changed and why.

This is the first article in a series of posts. Each post will walk you through a more advanced SQL query than the previous post, while demonstrating more insights which can be obtained from MySQL's execution plans.

The query and database …

MySQL supports replicating to a slave that is one release higher. This allows us to easily upgrade our MySQL setup to a new version, by promoting the slave and pointing the application to it. However, though unsupported, there are times when the MySQL version of slave deployed is one release lower. In this scenario, if your application has been performing much better on an older version of MySQL, you would like to have a convenient option to downgrade. You can simply promote the slave to get the old performance back.

The MySQL manual says that ROW based replication can be used to replicate to a lower version, provided that no DDLs replicated are incompatible with the slave. One such incompatible command is ALTER USER which is a new feature in MySQL 5.7 and not available on 5.6. :

ALTER USER …

In Jesper’s blog on Persisted Variables …he introduced us to this new capability using the PERSIST and PERSIST_ONLY keywords.  With new MySQL features, such as PERSIST come new areas that we need to pay attention to when doing backup and restore activities.  Namely to manage the log file that the PERSIST capability uses, as it’s a… Read More »