Shinguz's blog

Trx # 86153878218 exists in both Galera Cluster conflics which are 46 seconds apart (= long running transaction?). Table `rt3`.`Tickets` seems to be involved in both cases. One should investigate also in this query or transaction we cannot see here...

Very often I see some stupid error messages as a (power-)user. I do not know if this is because of lazy developers or managers not having enough focus on more useful error messages.

FromDual has the pleasure to announce the release of the new version 1.0.0 of its popular FromDual Ops Center focmm, a Graphical User Interface (GUI) for MySQL and compatible databases.

cd /var/log
ll -d -Z mysql* mysql/*
mkdir mysql
chown mysql: mysql
semanage fcontext -a -t mysqld_db_t "/var/log/mysql/(/.*)?"
restorecon -Rv /var/log/mysql
ll -d -Z mysql* mysql/*

And Non-standard database set up with SELinux

/usr/sbin/logrotate /etc/logrotate.conf

On StackExchange for Database Administrators I recently have seen a question which attracted my interest.

Recently we had a new customer who has had from time to time massive database problems which he did not understand. When we reviewed the MySQL configuration file (my.cnf) we found, that this customer had disabled the InnoDB Deadlock detection (innodb_deadlock_detect).

MariaDB/MySQL Stored Language is called SQL/PSM.
There are 4 different types of Stored Language: Stored Procedures, Stored Functions, Triggers and Events.

On 1 March 2020 FromDual became 10 years old! Sincere thanks are given to all our customers, partners and interested person for their support and good cooperation in the last 10 years. And we would be pleased to advise and support you again competently in the coming 10 years.

Recently we migrated a database system from MySQL 5.7 to MariaDB 10.3. Everything went fine so far just the following message started to pop-up in the MariaDB Error Log File with the severity Note:

FromDual has the pleasure to announce the release of the new version 0.9.3 of its popular FromDual Ops Center focmm, a Graphical User Interface (GUI) for MariaDB and MySQL.

When it comes to MariaDB/MySQL Database consulting engagements we often see, that our customers are very confused by many different technologies advertised to them.

FromDual has the pleasure to announce the release of the new version 1.1.0 of its popular Database Performance Monitor for MariaDB, MySQL and Galera Cluster fpmmm.

You are using an old version of the FromDual Performance Monitor for MariaDB and MySQL (fpmmm). Please consider using a more recent version.

Your InnoDB Redo Log Buffer is too small for large transactions. Make the InnoDB Redo Log Buffer (innodb_log_buffer_size) bigger if you have enough RAM available to avoid additional I/O.
1 Mibyte is good for databases with small transactions. 8 Mibyte is good for medium size transactions. 64 MiByte is good for large transactions.

Table of Contents

• Before you start
• Infinite Loop Example

Before you start

SQL> SET SESSION sql_mode='ORACLE';

Infinite Loop Example

DELIMITER /

BEGIN

LOOP
  SELECT 'Hello world from MariaDB anonymous PL/SQL block!';
END LOOP; 

END;
/

DELIMITER ;

Up to version 5.5 MariaDB and MySQL can be considered as “the same” databases. The official wording at those times was “drop-in-replacement”. But now we are a few years later and times and features changed. Also the official wording has slightly changed to just “compatible”.
FromDual recommends that you consider MariaDB 10.3 and MySQL 8.0 as completely different database products (with some common roots) nowadays. Thus you should work and act accordingly.

Table of Contents

• ifconfig
• ip
• ethtool --statistics
• nstat
• netstat --statistics
• ss
• Reasons for dropped packets
• Features of Network card
• Features of Network driver
• Network driver ring buffer
• TCP socket received and send buffer
• Flow Control
• Check over time: sar
• Dropwatch
• perf
• tcpdump
• /proc/net/netstat
• System Tap (stap)
• Literature

When we do MariaDB and MySQL Database server analysis we see from time to time systems with a lot of dropped packets on a network interface:

Modern Linux Systems have a mechanism called logrotate to rotate different log files.