MySQL won’t start [ERROR] Found option without preceding group in config file

Hey folks,

have you ever received a call for a MySQL on windows that stopped working after someone did something at their my.cnf? Then you try to start the service by cmd and get the following error.

mysqld: [ERROR] Found option without preceding group in config file C:\ProgramData\MySQL\MySQL Server 8.0\my.ini at line 1.
mysqld: [ERROR] Fatal error in defaults handling. Program aborted!

Well, for some reason, the editor that was used (no idea which one was), threw some random byte at the beginning of the file. To solve that (on windows at least), open the file on Notepad++, go to Format > Convert to ANSI. Save the file and start again the service.

What was the weirdest thing that happened to you on a Windows Server?

MySQL Error1075 – Incorrect table definition; What’s happening?

Hey Folks,

A few months ago, I found an issue, where, for some reason, someone ignored the warnings and tried to restore a backup from a different version of MySQL (or even MariaDB, IDK). And as a result, half the database was running without Primary Keys. So when a system was trying to update their schema, we were getting errors (like the error bellow) trowed at our face.

1075 - Incorrect table definition; there can be only one auto column and it must be defined as a key

Ok, first things first, you would like to run an ALTER TABLE TABLE_NAME_HERE
ADD PRIMARY KEY (ID);
and see if it works.  The error was being thrown because the table key doesn’t have a single index on it… if you have problems with duplicated records on it, you can try the following script to solve the issue.

First, get the max id from the table, and then run the following: 

UPDATE TABLE_NAME_HERE JOIN (SELECT @sequence := MAX_ID_HERE ) r SET id=@sequence:=@sequence+1 where id= DUPLICATED_ID_HERE;

WARNING

Be aware that, if the rows that were duplicated, where referenced as FK on another table, you will get some headache (well, you already have problems…) !!

MySQL Error ‘Unknown or incorrect time zone’ at a replica

Have you ever tried to do a MySQL replication at a different timezone/SO and got the following error message at SHOW REPLICA STATUS? Well, there are two ways to solve this, Error ‘Unknown or incorrect time zone: ‘America/Cuiaba” on query. Default database: ‘glpi_tiab’. Query: ‘BEGIN’

If you are on Linux, you can run the following and solve the problem (after a restart of the service).

$ mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql -u root mysql -p

On Windows, I found it to be easier if you download the timezone instead of build/import your own. You can download from here https://dev.mysql.com/downloads/timezones.html.

use mysql;
source /path/to/file/timezone_posix.sql;

Well, that’s it for today. See ya.

Retrieve the SQL Server Version from a Backup File

Have you ever been in the need to retrieve the SQL Server version that was used on a backup file?

Well, if for some weird reason that happens to you, the following SQL can help you. It won’t restore the database, it’ll just retrieve some basic info about it.

With that, you’ll have the DatabaseVersion (Internal Number Version) where the backup was from. You can also grab some useful information like the Server Name, Creation Date, and more.

RESTORE HEADERONLY FROM DISK = N'b:\backup\data_backup.bak'

Below we have a table of  Versions x Internal Number.

Version Internal Number Version Compat. Level
SQL Server 2019 895 – 904 150
SQL Server 2017 868 – 869 140
SQL Server 2016 852 130
SQL Server 2014 782 120
SQL Server 2012 706 110

I hope it helps!

How to send Telegram messages from SQL Server

Hi folks,
You usually receive notifications from SQLServer at your e-mail, right? A nice way to receive updates from your SQL Server Schedule job, it’s sending them through telegram. To do so, you’ll have to configure one additional step and choose Operating System (CmdExec) as a type of command. And to call the Telegram API, we can use a PowerShell command like the following:

powershell "Invoke-RestMethod -Uri 'https://api.telegram.org/bot{API-KEY}/sendMessage?chat_id={CHAT-ID}&text={TEXT}'"

Just replace the following keys with the proper value (don’t forget to remove the curly brackets too).

API-KEY: Your bot API key
CHAT-ID: The ID of the chat where you’ll receive the message, could be a single user, or a chat group
TEXT: Your beloved message.

What else do you use to achieve this kind of alers? Slack? healthchecks.io? Tell us 😉

Microsoft Ignite – Certification Voucher

Hey folks,

Do you enjoy learning new things? Between September 22 and September 24, Microsoft will be hosting their yearly Microsoft Ignite event. Of course, it’ll be online this time and free of charge :).

This year, you can earn a certification voucher and that’s awesome. You’ll be able to choose one certification from a specific list. Check the list of available certifications and the Terms and Conditions accessing the following link: https://docs.microsoft.com/pt-br/learn/certifications/microsoft-ignite-cloud-skills-challenge-2020-free-certification-exam.

MySQL 8 requested authentication method unknown

Hey folks,
Be aware when you’re migrating from MySQL 5.7 to 8.0 on how you’re doing and what kind of applications have access to it. The version 8.0 introduced a new authentication plugin called caching_sha2_password and it’s the default auth plugin now.  Here is the list of compatible connectors to check if your app is ok with that or if you should call the dev team.

Example: If, for some reason, you get stuck with the following error (PHP sample), you have to do a few changes.

Connect Error: SQLSTATE[HY000] [2054] The server requested authentication method unknown to the client

Edit your config file and set the option default-authentication-plugin with mysql_native_password value, restart the server and set the password again with the following command.

Config File:

[mysqld]
/... other configs .../
default-authentication-plugin=mysql_native_password

SQL:

ALTER USER 'adv'@'localhost' IDENTIFIED WITH mysql_native_password BY '1AB@8CD#E91F22!';

New users should be created the same way. Be aware that you have to do that just for users that the application will use. Regular users for DBAs and queries you don’t have to do that change.

So, look out before just doing a update on your server, or you could break your app 😉

MySQL InnoDB Buffer

Hi all,
Do you have a MySQL server running somewhere? I’ve seen many and many MySQL servers running with the default configuration, even the mysql_secure_installation command being ignored. Let’s talk about a tip to tune your server.

innodb_buffer_pool_chunk_size=134217728

This config, tells the server how many memory it can use, the default (using 8.0 and 5.7) its 128MB, that’s way less then it could be, in general. I usually set about 75% of the total ram of the server IF you just have the database on that server. With that, you have enough memory to accommodate OS processes and the MySQL. You can set this in your my.cfn file.

Be aware this is not a silver bullet, and if your server has a lot of ram, let’s say > 100GB, if you set at 75%, you still have about 25GB free, and that’s way more than the SO needs. So it’s all a matter of your server memory size.

Make sure you review this point on next time!

MySQL InnoDB Cluster setup

Hey folks, today I would like to show how easy is to do a HA cluster with MySQL InnoDB Cluster.

First a few things we must know: You’ll need at least 3 servers (for database) to do the job. We’ll need MySQL Shell on every server. Every node needs a two-way connection with each node (he need to be able to connect to the other node, and other nodes needs to be able to connect to the one). You will need a fourth server to work as a router. I’ll assume you already have a well configured MySQL Server on all three servers. Today I’ll be using version 8.

To be easier, every server will have an entry to the others on the hosts file. So let’s begin creating a common user on every server and give privileges enough to do the JOB. Be aware that I’m no focusing on security issues, like allowing the user to access the database from any IP, the best solution would be set the servers IPs.

CREATE USER 'syncron'@'%' IDENTIFIED BY 'Abacaxi22';
GRANT ALL PRIVILEGES ON *.* TO 'syncron'@'%' WITH GRANT OPTION;

1) Creating the cluster

Now let’s fire MySQL Shell on every node and prepare the server to join/create a InnoDB Cluster. If you never used this Shell, give it a try, it’s an awesome tool and it’s really easy to use and learn. We’ll basically use the dba commando for all of our needs today. Run dba.configureInstance() on every node and then, on the “main” server run the following.

You can run the Shell with mysqlch --uri=syncron@mysql1:3306 and voila. You’re on the server 1.

cluster = dba.createCluster('tasks') --Cluster name, take note
dba.getCluster('tasks').status()

After each command, you should see the following results. Look that I’m actually running the command on a server named mysql1.

Look at the status result, and see that after creating the cluster, we already have a node running and he’s a R/W node. And look at the ‘statusText’.. The cluster still not fault tolerant.

2) Adding a node to the cluster

Now let’s connect to the second server. On the second server, instead of connecting to itself, we’ll connect to the mysql1 server, so use the same command as before to spin the Shell. After that, let’s add the second instance to the cluster.

cluster = dba.getCluster('tasks') -- the cluster name, remember?
cluster.addInstance('syncron@mysql2:3306') -- now we use the second server uri

IF everything works as expected you’ll see the following as a result.

You can run the status on the cluster again to see how it’s now. But it still not fault tolerant. Do the same job on the third server (mysql3 on my environment) and THEN you can get the status and see the magic (or at least the status page of it).

Be aware that, the server now IS fault tolerant BUT, can tolerate just one. But take a closer look and see that we have just one node with R/W permission, the other two are R/O… and that’s how it works (in this case at least). How we handle the connections now that we have three different servers running? Easy… use the Mysql Router… Now to the fourth server.

3) The Router

That’s the easy step… just run .\mysqlrouter.exe --bootstrap syncron@mysql1:3306 and you’ll get the config file generated. That’s just the default configuration, take a look at the manual to achieve better results. The router will give you two port to handle the connections, one with R/W permission and the other one with R/O. It’ll handle the “reconnect” for your application if needed.

Easy huh? Go ahead and shut down one instance and look at the cluster status again. Now two extra tips..

  • If you get the following when trying to configure or join a cluster, you need to check the grant of the user, here we used the most of it, but you can manage the permissions to achieve a better (and more secure) login.

Access denied; you need SYSTEM_VARIABLES_ADMIN and PERSIST_RO_VARIABLES_ADMIN privileges for this operation (MySQL Error 3630)
  • If you plan to upgrade your server, do it with caution. You MUST do the R/W node at the END. Before shut down the server run set persist group_replication_start_on_boot=0; and set to true again after the upgrade and then restart it again.

Cheers!

Managing database changes with Sqitch

Nowadays everybody talks about continuous integration, automated test tools, and stuff like that. But almost every time it’s about testing applications. Let’s talk a little about Sqitch, “a database change manager” as they use to call themselves.

Let’s say you’re starting a new project and want to ensure every database change are managed and secured with tests? Just like with an app, you can write tests to ensure everything works and you can have a “revert” method for the changes too. Suppose you are changing a field type and start creating a backup column (fallback ;)), but something goes wrong on the meantime and for some reason, you can’t do a simple rollback… revert it and be happy.

What if your CI says that the application it’s fine and can be released to the production server but “a wild bug appears” and you NEED to revert to a previous version of your service, easy huh? With Docker and one command line, the service is up and running again. But what about the database changes your team did? Just call the revert and be happy :).

Have I mentioned that you can have multiples connection URI at the project and have different environments to apply the changes with a single command?!. Let’s see a few commands to create a simple MySQL database…

Create a folder, initialize GIT in it and initialize the Sqitch project.

mkdir awesomeapp
cd awesomeapp
git init .
sqitch init flipr --uri https://github.com/theory/sqitch-mysql-intro/ --engine mysql

Now you have a ready to go sqitch structure. Now let’s do some basic creates.

sqitch add createcustomeruser -n 'Creation of Customer table'

Add the create table script to the file inside the “deploy” dir.

CREATE TABLE customer (
id INTEGER PRIMARY KEY,
name VARCHAR(50)
);

Add the verify script, can be a simple select. Add the revert script, guess what’s the command, and after all, you can run the commands below and see the result.

sqitch deploy db:mysql://root@/awesomeapp
sqitch verify db:mysql://root@/awesomeapp
sqitch revert db:mysql://root@/awesomeapp

This was a quick explanation about Sqitch so go ahead and read more at their docs and tutorials, they are pretty good.