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Displaying posts with tag: galera (reset)
Percona XtraDB Cluster 8.0 New Feature: wsrep_sst_auth Removal

The problem

In PXC 5.6 and 5.7, when using xtrabackup-v2 as the SST method, the DBA must create a user with the appropriate privileges for use by Percona XtraBackup (PXB). The username and password of this backup user are specified in the wsrep_sst_auth variable.

This is a problem because this username and password was being stored in plaintext and required that the configuration file be secured.

The PXC 8.0 solution

(This feature is still under development and may change before PXC 8.0 GA)

Because the wsrep_sst_auth is only needed on the donor side to take a backup, PXC 8.0 uses an internal user (created specifically for use by PXC) with a randomly generated password. Since this user is only needed on the donor, the plaintext password is not needed on the joiner …

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Experimental Binary of Percona XtraDB Cluster 8.0

Percona is happy to announce the first experimental binary of Percona XtraDB Cluster 8.0 on October 1, 2019. This is a major step for tuning Percona XtraDB Cluster to be more cloud- and user-friendly. This release combines the updated and feature-rich Galera 4, with substantial improvements made by our development team.

Improvements and New Features

Galera 4, included in Percona XtraDB Cluster 8.0, has many new features. Here is a list of the most essential improvements:

  • Streaming replication supports large transactions
  • The synchronization functions allow action coordination (wsrep_last_seen_gtid, wsrep_last_written_gtid, wsrep_sync_wait_upto_gtid)
  • More granular and improved error logging. wsrep_debug is now a multi-valued variable to assist in controlling the logging, and logging messages have been significantly improved.
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Comparing Replication Technologies for MySQL Clustering: Part 1

Overview

Clustering provides high availability and disaster recovery, along with the ability to read-scale both locally and globally. Some clusters even provide active/active capabilities, which others have a single master.

Real time database replication is a must for clustering and other key business purposes, like reporting. There are a number of replication technologies available for MySQL, and some are even bundled into various solutions. When choosing a replication methodology, it is paramount to understand just how the data moves from source to target. In this blog post, we will examine how asynchronous, synchronous, and “semi-synchronous” replication behave when used for clustering. Also, we will explore how …

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Putting Galera SST Compression on the benchmark

I mentioned in my Galera crash (un)safe post that it’s bad if a SST is triggered on a large dataset. On a Galera node an SST will simply wipe the contents of the MySQL data directory and copy a snapshot from another node in the cluster. For consistency this is a favorable thing to do, but from an HA perspective it isn’t: one node in the cluster is unavailable and another one is acting as donor. This means, if you have a three node Galera cluster, only two are available where one has “degraded” performance.

This could have quite high impact, for instance in the proxysql_galera_checker script only synced nodes are selected to receive traffic. By default the donor nodes will not receive any traffic and now the cluster only has one node left to serve traffic. Don’t worry: if there are no synced …

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Percona XtraDB Cluster 5.7.27-31.39 Is Now Available

Percona is happy to announce the release of Percona XtraDB Cluster 5.7.27-31.39 on September 18, 2019. Binaries are available from the downloads section or from our software repositories.

Percona XtraDB Cluster 5.7.27-31.39 is now the current release, based on the following:

All Percona software is open-source and free.

Bugs Fixed

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Hyperconverging and Galera cluster

What is hyperconverging?

Hyperconverging is the latest hype: do things more efficiently with the resources that you have by cramming as many virtual machines on the same hypervisor. In theory this should allow you to mix and match various workloads to make the optimum use of your hypervisor (e.g. all cores used 100% of the time, overbooking your memory up to 200%, moving virtuals around like there is no tomorrow). Any cloud provider is hyperconverging their infrastructure and this has pros and cons. The pro is that it’s much cheaper to run many different workloads while the con clearly is when you encounter noisy neighbors. As Jeremy Cole said: “We are utilizing our virtual machines to the max. If you are on the same hypervisor as us, sorry!”

Apart from cloud providers, you could hyperconverge your infrastructure yourself. There are a few hardware/software vendors out there that will help you with that and at one of my …

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Percona XtraDB Cluster 5.6.45-28.36 Is Now Available

Percona is glad to announce the release of Percona XtraDB Cluster 5.6.45-28.36 on September 17, 2019. Binaries are available from the downloads section or from our software repositories.

Percona XtraDB Cluster 5.6.45-28.36 is now the current release, based on the following:

All Percona software is open-source and free.

Bugs Fixed

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Is Galera trx_commit=2 and sync_binlog=0 evil?

It has been almost 5 years since I posted on my personal MySQL related blog. In the past few years I have worked for Severalnines and blogging both on their corporate blog and here would be confusing. After that I forgot and neglected this blog a bit, but it’s time to revive this blog!

Speaking at Percona Live Europe – Amsterdam 2019

Why? I will be presenting at Percona Live Europe soon and this blog and upcoming content is the more in-depth part of some background stories in my talk on benchmarking: Benchmarking should never be optional. The talk will mainly cover why you should always benchmark your servers, clusters and entire systems.

If you wish to see me present, you can receive 20% discount using this code: CMESPEAK-ART. Now let’s move on to the real …

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Addressing common challenges when scaling out MySQL horizontally

When we explore strategies to scale our MySQL-based database layer, we realize that there are many different options. As opposed to proprietary solutions, open-source products nourish themselves from their communities and novel architectures or enhanced versions are generated, often incorporating other open source technologies. MySQL is not an exception.

Other players build completely different engines aiming to mitigate some of MySQL well-known weaknesses, but still support its wire protocol, with the challenge of sacrificing as little compatibility as possible.

In this white paper, we briefly discuss the scale-up vs scale-out dilemma, to then review the different scale-out strategies. We are also going to go over some of the most common MySQL architectures and products with horizontal scaling in mind.

Finally, we will share some guidelines to …

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How to Test MySQL Server Hostname with ProxySQL Multiplexing

Overview

While working on a MySQL Galera cluster with ProxySQL, I was in the process of testing traffic going to the MySQL nodes by using the @@hostname command to ensure which MySQL host behind the proxy the query ran on. This was important as my client is using query rules to route traffic according to the rule to either the master or the slave.  But to my surprise, I didn’t always get the result that I was expecting.  This is where ProxySQL multiplexing comes into play.

Scenario

In my scenario, I was on a test server connecting to ProxySQL which was then routing my queries to the MySQL Galera nodes.  I would connect into ProxySQL using the MySQL client.

Important note: When testing query routing with ProxySQL using comments and the MySQL client, you have to use the “-c” command line option in order for the comment to not be stripped away when running queries.  You …

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