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Fun with Bugs #51 - My Bug Reports that Oracle doesn't Want to Fix

This week I noticed (yet another) customer issue related to the output produced by mysqladmin debug command (or when mysqld process gets SIGHUP signal). I mean the output generated by the mysql_print_status() function. In this issue the content of the output was misinterpreted. I've seen this in the past more than once, and requested to document the output properly, but it never happened for a reason that there is an internal feature request to put this information elsewhere, in Performance Schema or Information Schema. The bug ended up with "Won't fix" status.

Surely I complained in a comment and on Facebook, and then …

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MySQL 8.0 roles

One of the most interesting features introduced in MySQL 8.0 is roles or the ability of defining a set of privileges as a named role and then granting that set to one or more users. The main benefits are more clarity of privileges and ease of administration. Using roles we can assign the same set of privileges to several users, and eventually modify or revoke all privileges at once.

Roles in a nutshell

Looking at the manual, we see that using roles is a matter of several steps.

(1) Create a role. The statement is similar to CREATE USER though the effects are slightly different (we will see it in more detail later on.)

mysql …
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Percona Server for MySQL 5.7.17-12 is Now Available

Percona announces the GA release of Percona Server for MySQL 5.7.17-12 on March 24, 2017. Download the latest version from the Percona web site or the Percona Software Repositories. You can also run Docker containers from the images in the Docker Hub repository.

Based on MySQL 5.7.17, including all the bug fixes in it, Percona Server for MySQL 5.7.17-12 is the current GA release in the Percona Server for MySQL 5.7 series. Percona’s …

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Group Replication GCS Troubleshooting

In the last post I shared the simple set of steps to configure a Group Replication setup using SQL commands, and a few in the configuration file too. Indeed, it can be simple.  But then there are times where there are more requirements and configurations need more attention. Maybe the OS environment we use for MySQL setups has never impacted us… Read More »

Percona Server 5.6.35-81.0 is Now Available

Percona announces the release of Percona Server 5.6.35-81.0 on March 24, 2017. Download the latest version from the Percona web site or the Percona Software Repositories. You can also run Docker containers from the images in the Docker Hub repository.

Based on MySQL 5.6.35, and including all the bug fixes in it, Percona …

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What to Do When the MySQL Optimizer Overestimates the Condition Filtering Effect

In my previous blog post, I showed an example of how the MySQL Optimizer found a better join order by taking into account the filtering effects of conditions. I also explained that for non-indexed columns the filtering estimate is just a guess, and that there is a risk for non-optimal query plans if the guess is off.

We have received a few bug reports on performance regressions when upgrading from 5.6 to 5.7 that are caused by the optimizer overestimating the filtering effect. In most cases, the cause of the regression is inaccurate filtering estimates for equality conditions on non-indexed columns with low cardinality. In this blog post, I will discuss three ways to handle such regressions:

  1. Create an index
  2. Use an optimizer hint to change the join order
  3. Disable condition filtering
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How to Install Cerb Collaboration and Email Automation on CentOS 7

Cerb is a free and open source web-based application software for collaboration and email automation. It is written in PHP language and uses MySQL/MariaDB as a database. It is used for sending a large number of emails. Here, we will explain how to install Cerb on CentOS 7 server.

SQL*Loader-704: Internal error: ulconnect:OCIServerAttache [0] ORA-12154: TNS:could not resolve the connect identifier specified

  When you see the above error , first thing come into mind is  Is our tnsnames.ora file is exist , if its there used connection string is there If you have it correctly and still issue is persist .. Then whats happens everything is good  1.First thing you have to check if tnsnames is fine sqlldr scott/HD@y45Hhds@orcl control=E:\test\table.ctl log=E:\test\table.log Check if you have password having '@' symbol 2.Then change it as below , you will be able to load the millions of files into oracle table  sqlldr scott/\"HD@y45Hhds\"@orcl control=E:\test\table.ctl log=E:\test\table.log Make it useful ..

Percona Live Featured Session with Luís Soares: The New MySQL Replication Features in MySQL 8

Welcome to another post in the series of Percona Live featured session blogs! In these blogs, we’ll highlight some of the session speakers that will be at this year’s Percona Live conference. We’ll also discuss how these sessions can help you improve your database environment. Make sure to read to the end to get a special Percona Live 2017 registration bonus!

In this Percona Live featured session, we’ll meet Luís Soares, Principal Software Engineer at Oracle. His session is The New MySQL Replication Features in MySQL 8 (with fellow presenter Lars Thalmann, Development Director at Oracle). The most popular high availability …

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MySQL Group Replication: native support in ProxySQL

ProxySQL is the leader in proxy and load balancing solution for MySQL. It has great features like query caching, multiplexing, mirroring, read/write splitting, routing, etc… The latest enhancement in ProxySQL is the native support of MySQL Group Replication. No more need to use an external script within the scheduler like I explained in this previous post.

This implementation supports Groups in Single-Primary and in Multi-Primary mode. It is even possible to setup a Multi-Primary Group but dedicate writes on only one member.

René, the main developer of ProxySQL, went even further. For example in a 7 nodes clusters (Group …

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