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Displaying posts with tag: troubleshooting (reset)
Investigating a MySQL dead lock

I was involved in one of the development support for MySQL. Here is an interesting case

The application needs a Sequence generator as it was not present inbuilt with MySQL ( MariaDB will have it in 10.3 ) they have made sequence generator function with ‘select for update‘ statement. But it tends to cause more locking at high concurrency with their XtraDB Cluster deployment.

To get rid of this , the sequence generation were made as direct Update queries and sequence is fetched using Select @next.

UPDATE EO_PK_TABLE SET PK = (@next := PK …
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Webinar Thursday, January 25, 2018: Troubleshooting MySQL Crashes

Please join Percona’s Principal Support Engineer, Sveta Smirnova, as she presents Troubleshooting MySQL Crashes on January 25, 2018, at 10:00 am PST (UTC -8) / 1:00 pm EST (UTC -5).

Register Now

 

This webinar is for every MySQL user! In this talk, I won’t focus on how to analyze core files, read the source code or set breakpoints. Instead, I will focus on techniques that are available to anyone, even a novice.

Many tutorials, including my own, written based on Roel Van de Paar’s video, suggest how to create and analyze core files created at the time of a crash. While this …

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Making Maxscale/ProxySQL Highly Available ( 2 > 1 )

As Mydbops we are implementing Load Balancer using Maxscale or ProxySQL ( Our presentation ) for lot our client,  but these load balancers will become a SPOF (Single Point of failure) .  We have tried to explore services like HAProxy, Nginx, and Keepalived etc. Except Keepalived, all the services need to run on the standalone instance and  did not satisfy our exact need.

Keepalived does not requires any standalone instance, it can be deployed and configured with a minimal effort and provide the HA Solutions to the DB Infra. This approach not only fits for our DB setup, we can implement same …

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Replication Will not Start On AWS RDS for MariaDB 10.2

AWS recently announced the release of MariaDB 10.2 for RDS. One of customer needs this release for GIS indexing .The recent encounter on a Replication issue with RDS MariaDB 10.2 is briefed here .

Problem Statement:

After the upgrade of replicas to MariaDB 10.2 on RDS, Once replication is stopped manually through “call mysql.rds_stop_replication;” or replication failed due to some error. Replication cannot be started back using “call mysql.rds_start_replication;” and there is no straightforward way or documented process to start the replication back. Also, most of the replication related RDS commands like skip errors etc will not work. This is due to the implementation of replication handling in RDS.

Summary:

On Jan 5, 2018, RDS announced support for MariaDB 10.2.  …

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Webinar January 18, 2018: MySQL Troubleshooting and Performance Optimization with Percona Monitoring and Management (PMM) Part 2

Join Percona’s Product Manager Michael Coburn as he presents MySQL Troubleshooting and Performance Optimization with Percona Monitoring and Management (PMM) Part 2 on Thursday, January 18, 2018, at 11:00 am PST / 2:00 pm EST (UTC-8).

Register Now

Tags: Percona Monitoring and Management, PMM, Monitoring, MySQL, Performance, Optimization, DBA, SysAdmin, DevOps
Experience Level: Expert

Optimizing MySQL performance and troubleshooting MySQL problems are two of the most critical and challenging tasks for …

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Disabling Multi-Source Replication in MySQL 5.7

Multi-channel replication is one of the  great feature shipped with MySQL 5.7, With allowed the capability of slave to have many masters, having a channel for each master by which they replicate. Each channel id has a unique “channel_name” Multi-Channel ReplicationIn the above DB Architecture “channel_1, channel_2 and channel_3” represent the channel_name used for replication from different MySQL servers ( Source ). In this blog we are not going see about configuration of multi_source replication, rather we are going to see about rolling back multi-source replication in MySQL. Recently we were working on a client, where we had deployed multi-channel replication replication from two master onto a single slave, sync was happening very fine Then came the situation to break the replication from two channel and make …

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Ulimit conflict with PAM and Systemd​​​

As a part of the MySQL Support, we had a support request from a client.The issue is DB server runs out of open files limit, though it is configured. It causes the DB hang and crash at times. Sometimes they can’t able to fix. So we plan to write our experience with configuring. We believe this article can help in configuring appropriate Ulimit value without any obstacles. Let us jump to the subject. What are the errors we might face while ulimit is not properly configured?

  1. Too many open files
  2. System unable to allocate necessary resources for the monitor thread
  3. can’t create new thread, closing connection

The above-shared list is just sample’s, maybe people who currently reading this blog may also face issue related to ulimit, for that they may have different debug …

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Troubleshooting MySQL Performance Issues

Despite your very best efforts, as tables increase in size and more and more users come online, sluggish MySQL performance eventually rears its ugly head. When that happens, you may be tempted to shrug it off as part of doing business. Don’t. By understanding the mechanisms behind database slowdowns and by methodically attacking the problem, you can home in on the culprit(s) and remedy the issues in a timely manner, before your business suffers substantial losses as a result.

The purpose of this blog is to assist you in determining the cause(s) of MySQL database performance issues using a couple of built-in tools.

Why Database Performance Slows Down

It’s no secret that database performance tends to degrade over time. While it’s easy to point the finger at the number of concurrent users, table scans, and growing tables, the reality is more complex than that. The most common reason for slow database performance is …

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Stepicon 2017 and thoughts on MySQL MOOCs

I periodically do MySQL Troubleshooting tutorials. Every time I run them I have a dilemma on how to make tutorials more interactive. I tried:

  1. Just talk. But troubleshooting is about action, not about sitting and listening 
  2. Put tasks on my own website which required a lot of coding, not related to the talk and tasks themselves.
  3. Put tasks on VirtualBox image. Many attendees do not want to use flash drive or download big image from Internet.
  4. Put tasks into Amazon EC2 instance. This is practically good option, but expensive.
  5. Use machines, provided by tutorial organizers (conference or training center). This is, probably, the best option, but few do it.

I did not like any of these options as final solution. That's why for my last two tutorials I tried Stepik platform. This is how " …

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My First Steps with MariaDB ColumnStore

This is a "Howto" kind of post, and some speculations and historical references aside, it will show you how to build MariaDB ColumnStore (current version 1.0.9) from GitHub source, how to install and configure it for basic usage, as well as how to resolve some minor problems you may get in the process. Keep reading and eventually you'll get the real Howto below :)

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I try not to care about any software issues besides good old MySQL, InnoDB storage engine internals, query optimization and some MyRocks or a little bit of …

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