Tag: mysql

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MySQL

Stop installing MySQL 5.6!

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From time to time, I get a customer request to configure/optimize a MySQL server, and usually, when the customer has already installed the MySQL Server, usually, it’s an “old” version. It’s ok if your software uses features that only work on some specific version of a Database, but keep an eye open for its end of life support. And that EOF is coming to MySQL 5.6. Below you can see a table with the MySQL versions and their ending date.

So, next time you need to configure a new server, keep an eye on the version you’re using.

Version Ending date
5.6 02/05/2021
5.7 10/21/2023
8.0 04/xx/2026
Errors and Bugs, MySQL

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

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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?

Backup and Restore, Errors and Bugs, MySQL

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

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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…) !!

Database, MySQL

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

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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.

Database, Errors and Bugs, MySQL

MySQL 8 requested authentication method unknown

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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, Performance

MySQL InnoDB Buffer

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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

MySQL InnoDB Cluster setup

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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!

Database, MySQL, Shell Scripts

MySQL: Sed for Scripts using “Show” from Command Line

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Hi all,
So, a pretty basics one today… But useful to have handy. How to script an output from  mysql -B -e?

Easy, by using SED. Ok, by replacements are always tricky considering the line braking and etc. So, here goes an example with show tables:

Original Output.

[root@greporasrv ~]# mysql sbtest -B -e 'show tables'
Tables_in_sbtest
sbtest1
sbtest10
sbtest2
sbtest3
sbtest4
sbtest5
sbtest6
sbtest7
sbtest8
sbtest9
Cool, now with all in one line:
[root@greporasrv ~]# mysql sbtest -B -e 'show tables'|sed ':a;N;$!ba;s/\n/ /g'
Tables_in_sbtest sbtest1 sbtest10 sbtest2 sbtest3 sbtest4 sbtest5 sbtest6 sbtest7 sbtest8 sbtest9

Great, so let’s put some useful code on it:

[root@greporasrv ~]# mysql sbtest -B -e 'show tables'|sed ':a;N;$!ba;s/\n/ engine=innodb; \n alter table /g'
Tables_in_sbtest engine=innodb;
alter table sbtest1 engine=innodb;
alter table sbtest10 engine=innodb;
alter table sbtest2 engine=innodb;
alter table sbtest3 engine=innodb;
alter table sbtest4 engine=innodb;
alter table sbtest5 engine=innodb;
alter table sbtest6 engine=innodb;
alter table sbtest7 engine=innodb;
alter table sbtest8 engine=innodb;
alter table sbtest9 engine=innodb;

Hope you can use for your needs.

Cheers!

Database, Errors and Bugs, MySQL

MySQL: ERROR 1356 (HY000): View ‘sys.innodb_lock_waits’ references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them

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Hello all!
So, I was messing around with a Dev environment to simulate some strategies, doing some tests, and after a mysqldump exporting, dropping, and reimporting my whole database got this error.

If you arrived here from Google, Is this your case?

Well, this happens for a simple reason. The routines are not exported by mysqldump by default. Why? I don’t know either, this is an abomination to me. This would be very cheap to be the default right?

Happens that even for a new database, when importing a dump generated with –all-databases the sys/information_schema routines are deleted by the restore process. Well, at least this is recognized as a Bug (Bug 83259).

I noticed that when trying to query a sys view to get locks info, as per:

root@localhost-(none)-13:46:26>SELECT waiting_trx_id, waiting_pid, waiting_query, blocking_trx_id,
-> blocking_pid, blocking_query FROM sys.innodb_lock_waits;
ERROR 1356 (HY000): View 'sys.innodb_lock_waits' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them

Hm.. Weird message, let’s check for information_schema objects:

root@localhost-(none)-13:46:39>select count(*) from information_schema.ROUTINES where ROUTINE_SCHEMA='sys';
+----------+
| count(*) |
+----------+
| 0 |
+----------+
1 row in set (0.00 sec)

Ok, so, if you are already in this mess, how to quick recover?
Well, just run the mysql_upgrade (assuming you are in the top version/repository you have available on server):

root@localhost-(none)-13:47:34>exit
Bye
[root@greporasrv ~]# mysql_upgrade
Checking if update is needed.
Checking server version.
Running queries to upgrade MySQL server.
Checking system database.
mysql.columns_priv OK
mysql.db OK
mysql.engine_cost OK
mysql.event OK
mysql.func OK
mysql.general_log OK
mysql.gtid_executed OK
mysql.help_category OK
mysql.help_keyword OK
mysql.help_relation OK
mysql.help_topic OK
mysql.innodb_index_stats OK
mysql.innodb_table_stats OK
mysql.ndb_binlog_index OK
mysql.plugin OK
mysql.proc OK
mysql.procs_priv OK
mysql.proxies_priv OK
mysql.server_cost OK
mysql.servers OK
mysql.slave_master_info OK
mysql.slave_relay_log_info OK
mysql.slave_worker_info OK
mysql.slow_log OK
mysql.tables_priv OK
mysql.time_zone OK
mysql.time_zone_leap_second OK
mysql.time_zone_name OK
mysql.time_zone_transition OK
mysql.time_zone_transition_type OK
mysql.user OK
The sys schema is already up to date (version 1.5.1).
Found 0 sys functions, but expected 22. Re-installing the sys schema.
Upgrading the sys schema.
Checking databases.
mysqlslap.t1 OK
[... my other databases...]
sys.sys_config OK
world.city OK
world.country OK
world.countrylanguage OK
Upgrade process completed successfully.
Checking if update is needed.

Fine, lets test it:

[root@greporasrv ~]# mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 32
Server version: 5.7.24-log MySQL Community Server (GPL)

Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

root@localhost-(none)-13:49:44>select count(*) from information_schema.ROUTINES where ROUTINE_SCHEMA='sys';
+----------+
| count(*) |
+----------+
| 48 |
+----------+
1 row in set (0.00 sec)

root@localhost-(none)-13:49:53>

Hope it helps.
Cheers!