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Displaying posts with tag: Q&A (reset)
Zero-Downtime Cluster Maintenance: Comparing the Procedures for Upgrades versus DB/OS Maintenance

Overview The Skinny

Part of the power of Tungsten Clustering for MySQL / MariaDB is the ability to perform true zero-downtime maintenance, allowing client applications full access to the database layer, while taking out individual nodes for maintenance and upgrades. In this blog post we cover various types of maintenance scenarios, the best practices associated with each type of action, and the key steps to ensure the highest availability.

Important Questions Understand the Environment as a Whole First

There are a number of questions to ask when planning cluster maintenance that are critical to understand before starting.

For example:

  1. What is the cluster topology?
    • Standalone (connectors write to single cluster master)
      Single cluster: …
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How to move the Relay role to another node in a Composite Tungsten Cluster

The Question Recently, a customer asked us:

How would we manually move the relay role from a failing node to a slave in a Composite Tungsten Cluster passive site?

The Answer The Long and the Short of It

There are two ways to handle this procedure manually when the usual switch command fails to work as expected. One is short and reasonably automated, and the other is much more detailed and manual.

Of course, the usual procedure is to just issue the switch command in the passive cluster:

use west
set policy maintenance
switch
set policy automatic

The below article describes what to do when the switch command does not move the relay role to another node.

SHORT

Below is the list of cctrl commands that would be run for the basic, short version, which (aside from handling policy changes) is really only …

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MySQL 8.0 GA: Quality or Not?

What does Anton Ego – a fictional restaurant critic from the Pixar movie Ratatouille – have to do with MySQL 8.0 GA?

When it comes to being a software critic, a lot.

In many ways, the work of a software critic is easy. We risk very little and thrive on negative criticism, which is fun to read and write.

But what about those who give their many hours of code development, and those who have tested such code before release? How about the many people behind the scenes who brought together packaging, documentation, multiple hours of design, marketing, online resources and more?

And all of that, I might add, is open source! Free for the world to take, copy, adapt and even incorporate in full or in part into their own open development.

It is in exactly that area that the …

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Webinar Q&A: Percona XtraDB Cluster 101

In this blog, we will answer questions from our webinar on Percona XtraDB Cluster 101.

Recently (7 Dec 2017) I presented a webinar about Percona XtraDB Cluster 101. Firstly, thanks to all the attendees: we had a great webinar with quite some interesting questions and feedback.

Through this blog, I’ll answer most of the questions that were raised during the webinar.

Q. How does the need for the acknowledgment from other nodes affect the speed of writes?

A. There are two parts to replication: delivering a transaction (including acknowledgment) and applying the transaction. …

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Thoughts on MySQL 8.0.3 RC – The First MySQL 8.0 Release Candidate

Percona’s Technical Director of Quality Assurance Roel Van de Paar shares his findings on the quality of MySQL 8.0.3 RC.

On 21 September 2017, our upstream friends at Oracle released MySQL 8.0.3 RC as the first MySQL 8.0 Release Candidate.

I tested the MySQL 8.0.3 Release Candidate branch with selected Percona bugfixes applied and built it as debug using the pquery QA framework (freely available here). Percona releases Percona Server for MySQL – an improved fork of the MySQL server – with additional features and bug patches.

Any QA engineer would enjoy seeing the many bugs discovered:

================ [Run: 079328] Sorted unique issue strings (11258 trials executed, …
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Learning MySQL 5.7: Q & A

In this post I’ll answer questions I received in my Wednesday, July 19, 2017, webinar Learning MySQL 5.7!

First, thank you all who attended the webinar. The link to the slides and the webinar recording can be found here.

I received a number of interesting questions in the webinar that I’ve followed up with below.

Would there be a big difference on passing from 5.1 to 5.6 before going to 5.7 or, at this point, would it be roughly the same?

The biggest risk of jumping between versions, in this case 5.1 to 5.6, is reverting in case of problems. Rollbacks don’t happen often, but they do happen and you have to make …

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Q & A: MySQL In the Cloud – Migration, Best Practices, High Availability, Scaling

In this blog, we will provide answers to the Q & A for the MySQL In the Cloud: Migration, Best Practices, High Availability, Scaling webinar.

First, we want to thank everybody for attending the June 7, 2017 webinar. The recording and slides for the webinar are available here. Below is the list of your questions that we were unable to answer during the webinar:

How does Percona XtraDB cluster work with AWS for MySQL clustering?

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MySQL QA Episode 11: Valgrind Testing: Pro’s, Con’s, Why and How

Today’s episode is all about Valgrind – from the pro’s to the con’s, from the why to the how! This episode will be of interest to anyone who is or wants to work with Valgrind on a regular or semi-regular basis.

  1. Pro’s/Why
  2. Con’s
  3. How
    1. Using the latest version
      sudo [yum/apt-get] install valgrind
      #OR#
      sudo [yum/apt-get] remove valgrind
      sudo [yum/apt-get] install bzip2 glibc*
      wget http://valgrind.org/downloads/valgrind-3.10.1.tar.bz2
      tar -xf valgrind-3.10.1.tar.bz2; cd valgrind-3.10.1
      ./configure; make; sudo make install
      valgrind –version # This should now read 3.10.1
    2. VGDB (cd ./mysql-test)
      ./lib/v1/mysql-test-run.pl –start-and-exit –valgrind –valgrind-option=”–leak-check=yes”
      –valgrind-option=”–vgdb=yes” …
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MySQL QA Episode 10: Reproducing and Simplifying: How to get it Right

Welcome to the 10th episode in the MySQL QA series! Today we’ll talk about reproducing and simplifying: How to get it Right.

Note that unless you are a QA engineer stuck on a remote, and additionally difficult-to-reproduce or difficult-to-reduce bug, this episode will largely be non-interesting for you.

However, what you may like to see – especially if you watched episodes 7 (and possibly 8 and 9) – is how reducer automatically generates handy start/stop/client (cl) etc. scripts, all packed into a handy bug tarball, in combination with the reduced SQL testcase.

This somewhat separate part is covered directly after the introduction (ends at 11:17), as well as with an example towards the end of the video (starts at time index 30:35).

The “in between part” (11:17 to 30:35) is all about reproducing and simplifying, which – unless you are working on a remote case – can likely be skipped by …

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MySQL QA Episode 9: Reducing Testcases for Experts: multi-threaded reducer.sh

Welcome to MySQL QA Episode 9. This episode will go more in-depth into reducer.sh: Reducing Testcases for Experts: multi-threaded reducer.sh

We will explore how to use reducer.sh to do true multi-threaded testcase reduction – a world’s first.

Topics:

  1. Expert configurable variables & their default reducer.sh settings
    1. PQUERY_MULTI
    2. PQUERY_MULTI_THREADS
    3. PQUERY_MULTI_CLIENT_THREADS
    4. PQUERY_MULTI_QUERIES
    5. PQUERY_REVERSE_NOSHUFFLE_OPT

Full-screen viewing @ 720p resolution recommended.

The post MySQL QA Episode 9: Reducing Testcases for Experts: multi-threaded reducer.sh appeared first on …

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