Overview The Skinny

Tungsten Clustering provides high availability, disaster recovery, and a host of other benefits for MySQL / MariaDB / Percona Server databases. In this blog post we will explore some of the shell aliases I use every day to administer various Tungsten Clusters.

Shell Aliases: A Quick Review Quick and Easy

A shell alias is simply a way to create a shortcut for frequently-used command sequences.

For example, I like to shorten the command clear to cls, i.e.

shell> alias cls=clear
shell> cls

If you create an alias on the fly it will be lost when the shell exits.

To save aliases so they are available to all shell sessions, update your shell’s profile or rc script.

For example, add the below line to the bottom of …

Are you looking to get started with the world’s most popular open-source database, and wondering how you should setup your MySQL hosting? So many default to Amazon RDS, when MySQL performs exceptionally well on Azure Cloud. While Microsoft Azure does offer a managed solution, Azure Database, the solution has some major limitations you should know about before migrating your MySQL deployments. In this post, we outline the best way to host MySQL on Azure, including managed solutions, instance types, high availability replication, backup, and disk types to use to optimize your cloud database performance.

MySQL DBaaS vs. Self-Managed MySQL

The first thing to consider when weighing between self-management and a MySQL Database-as-a-Service …

Author: Robert Agar

The working life of a DBA is often centered on optimizing their systems to provide users with the best performance. There are many aspects of a MySQL implementation that can be tuned to increase its functionality. These improvements will result in a more efficient system and enhanced user experience.

One of the problems facing the DBA responsible for instituting performance tuning is to identify the particular areas to address that will impact the system in a positive manner. Approaching this task in a haphazard fashion is not advisable. Randomly modifying parameters is just as likely to cause further issues than to lead to performance gains. Luckily, there is a solution to this dilemma.

Conducting focused monitoring can be instrumental in enabling the DBA to pinpoint the source of performance degradation. Armed with this knowledge, informed decisions can be made regarding how …

The Question Recently, a customer asked us:

What is the meaning of this error message found in trepsvc.log?

2019/05/14 01:48:04.973 | mysql02.prod.example.com | [east - binlog-to-q-0] INFO pipeline.SingleThreadStageTask Performing rollback of possible partial transaction: seqno=(unavailable)

Simple Overview The Skinny

This message is an indication that we are dropping any uncommitted or incomplete data read from the MySQL binary logs due to a pending error.

The Answer Safety First

This error is often seen before another error and is an indication that we are rolling back anything uncommitted, for safety. On a master this is normally very little and would likely be internal transactions in the trep_commit_seqno table, for example.

As you may know with the replicator we always extract complete transactions, and so this particular message is …

Overview The Skinny

In this blog post we will discuss how the managed cross-site replication streams work in a Composite Multi-Master Tungsten Cluster for MySQL, MariaDB and Percona Server.

Agenda What’s Here?

• Briefly explore how managed cross-site replication works in a Tungsten Composite Multi-Master Cluster
• Describe the reasons why the default design was chosen
• Explain the pros and cons of changing the configuration
• Examine how to change the configuration of the managed cross-site replicators

Cross-Site Replication A Very Brief Summary

In a standard Composite Multi-Master (CMM) deployment, the managed cross-site replicators pull Transaction History Logs (THL) from every remote cluster’s current master node. …

The Question Recently, a customer asked us:

Why would Tungsten Replicator be slow to apply to MySQL?

The Answer Performance Tuning 101

When you run trepctl status and see:
appliedLatency : 7332.394
like this on a slave, it is almost always due to the inability for the target database to keep up with the applier.

This means that we often need to look first to the database layer for the solution.

Here are some of the things to think about when dealing with this issue:

Architecture and Environment
√ Are you on bare metal?
√ Using the cloud?
√ Dev or Prod?
√ Network speed and latency?
√ Distance the data needs to travel?
√ Network round trip times? Is the …

The Question Recently, a customer asked us:

If we move to using the INI configuration method instead of staging, would password-less SSH still be required?

The Answer The answer is both “Yes” and “No”

No, for installation and updates/upgrades specifically. Since INI-based configurations force the tpm command to act upon the local host only for installs and updates/upgrades, password-less SSH is not required.

Yes, because there are certain commands that do rely upon password-less SSH to function. These are:

• tungsten_provision_slave
• prov-sl.sh
• multi_trepctl
• tpm diag (pre-6.0.5)
• tpm diag --hosts (>= 6.0.5)
• Any tpm-based backup and restore operations that involve a remote node

Summary The Wrap-Up

In …

Overview The Skinny

In this blog post we will discuss how to best integrate various Continuent-bundled cluster monitoring solutions with PagerDuty (pagerduty.com), a popular alerting service.

Agenda What’s Here?

• Briefly explore the bundled cluster monitoring tools
• Describe the procedure for establishing alerting via PagerDuty
• Examine some of the multiple monitoring tools included with the Continuent Tungsten Clustering software, and provide examples of how to send an email to PagerDuty from each of the tools.

Exploring the Bundled Cluster Monitoring Tools A Brief Summary

Continuent provides multiple methods out of the box to monitor the cluster health. The most popular is the suite of Nagios/NRPE scripts (i.e. cluster-home/bin/check_tungsten_*). We also have Zabbix scripts (i.e. cluster-home/bin/zabbix_tungsten_*). Additionally, there is …

Wondering which databases are trending in 2019? We asked hundreds of developers, engineers, software architects, dev teams, and IT leaders at DeveloperWeek to discover the current NoSQL vs. SQL usage, most popular databases, important metrics to track, and their most time-consuming database management tasks. Get the latest insights on MySQL, MongoDB, PostgreSQL, Redis, and many others to see which database management systems are most favored this year.

SQL vs. NoSQL

As any database administrator knows, the first question you have to ask yourself is whether to use a SQL or NoSQL database for your application. …

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MySQL changed the timestamp format in the log files in MySQL 5.7. Since then, I have a few times seen questions about the new format, and how to change the time zone that is used. Latest in a comment to my blog about log_slow_extra in 8.0.14, where the question was what T and Z in the timestamp (for example 2019-01-31T07:24:06.100447Z) means. In this blog, I will discuss the timestamp format and show you how you can change the time zone used.

Examples of the timestamps from the MySQL error log when restarting MySQL (click to enlarge).
The MySQL 5.7 Change

In MySQL 5.7 it was decided to make two …