Shinguz's blog

We get ever and ever again customer requests concerning Deadlocks. First of all, Deadlocks are usually an application problem, not a database problem! The database itself manifests the application problem with the following message which is sent to the application as an error:

Is this not just a simple an Anonymous PL/SQL Block?

Also in 2022 there will be a FOSDEM (Free and Open source Software Developers’ European Meeting) on 5 and 6 February 2022. This time again online from Brussels (Belgium).

The MariaDB Connection ID exists since long ago. So why bother about the Connection ID? Because it is interesting and you can do some interesting things with the Connection ID like tracking statements in your connections and find where they come from your application code.

XXX means Thread ID (= Connection ID) and YYY wsrep transaction sequence number (wsrep_last_committed?):

From 25 to 29 October 2021 (calendar week 43) we will have another MariaDB / MySQL advanced training in the Linuxhotel in Essen (Germany). The training is in German and will take place on-site (3G!). There are still some places free!

We currently have the situation that a customer cannot upgrade its hyper-consolidated Galera Cluster for more than a year because various different applications cannot, are not willing to or do not have the time to test against the newer version.

Nearly everybody does backups. But nobody needs backups! What everybody wants and needs is a working restore not a working backup…

FromDual has the pleasure to announce the release of the new version 2.2.4 of its popular Backup and Recovery Manager for MariaDB and MySQL (brman).

Foreign Key Constraints are used to model a parent/child relation in an entity relationship (ER) model:

Table of Contents

• What is SNMP?
• SNMP Agent (snmptrap)
• SNMP Manager (snmptrapd)
• Test the SNMP Agent
• Creating your own MIB
• Sending MariaDB SNMP traps from PHP
• Literature

What is SNMP?

A customer recently had the question if an how his MariaDB database can be easily monitored with SNMP?

Hello Leo

Thank you for your question. What did you try so far? Or where did you stuck? Can you show us the query you have created so far?

This is my cheat sheet for dimensional modelling design techniques of a data warehouse (DWH) according to Kimball/Ross.

Storage Engines like InnoDB, Aria and MyISAM are Row Stores. They store rows one after the other in blocks or even directly in a single file (MyISAM). On the other hand a Column Store like MariaDB ColumnStore stores all the same attributes (columns) of the rows together in chunks.

#
# /etc/systemd/system/glbd.service
#

[Unit]
Description=Galera Load Balancer Service
After=network.target

[Service]
#
# adjust the EnvironmentFile variable for your distribution
#
# On Redhat and derivatives it should be /etc/sysconfig/glbd.conf
#
# On Debian  and derivatives it should be /etc/default/glbd.conf
#
EnvironmentFile=/etc/sysconfig/glbd.conf
Type=simple
ExecStart=/usr/sbin/glbd --daemon --threads $THREADS --max_conn $MAX_CONN $OTHER_OPTIONS --control $CONTROL_ADDR $LISTEN_ADDR $DEFAULT_TARGETS

[Install]
WantedBy=multi-user.target

#
# This is a configuration file for glbd service script
#
# On Red Hat and derivatives it should be placed in /etc/sysconfig/glbd.conf
#
# On Debian  and derivatives it should be placed in /etc/default/glbd.conf
#
# All settings besides LISTEN_ADDR are optional.
#

# Address to listen for client connections at. Mandatory parameter.
# To bind to all interfaces only port should be specified.
#LISTEN_ADDR="0.0.0.0:3306"

# Address for controlling connection. Mandatory part is port.
# If not specified control socket will not be opened
#CONTROL_ADDR="127.0.0.1 8081"

# Control FIFO name. It is opened always. glbd will refuse to start if
# this file already exists.
#CONTROL_FIFO="/var/run/glbd.fifo"

# Number of threads (connection pools) to use. It is always a good idea
# to have a few per CPU core.
#THREADS="4"

# Maximum connections. System open files limit will be modified to accommodate
# at least that many client connections provided sufficient privileges.
# Normally you should set it if you plan to go above 500.
# 3 x max_connections = 3 * 151 = 453
#MAX_CONN="450"

# Target servers for client connections, space separated.
# Target specification: IP[:PORT[:WEIGHT]] (WEIGHT and PORT optional)
# WEIGHT defaults to 1, PORT defaults to LISTEN_ADDR port.
#DEFAULT_TARGETS="192.168.0.1:3306:1 192.168.0.2:3306:1 192.168.0.3:3306:1"

# Other glbd options if any as they would appear on the command line.
# --least --round --single --random --source
#OTHER_OPTIONS="--round"

Table of Contents

• Hardware requirements
• O/S (Linux) settings
• Installation
• Configuration
• Cross Engine Join User
• Start ColumnStore
• Create the Cross Engine Join User in the database
• MariaDB ColumnStore schemas
• Server System Variables and Server Status Variables
• MariaDB ColumnStore on the file system
• Creating our first table
• Querying and changing data in MariaDB ColumnStore
• MariaDB ColumnStore using sequences instead of AUTO_INCREMENT
• MariaDB ColumnStore Query Execution Plan

For a long time I wanted to investigate a bit more into the MariaDB ColumnStore architecture. Now I took the time to start with.

FromDual has the pleasure to announce the release of the new version 1.1.0 of its popular FromDual Ops Center focmm, a Graphical User Interface (GUI) for MariaDB, MySQL and compatible databases.

Today a customer gave me the idea of using a separate file as a volume for limiting the MySQL tmpdir size. On some not so well set-up Linux systems the MySQL tmpdir is located under /tmp which is the same mount point as / (root). This can lead to troubles in case the tmpdir is filled up with implicit temporary MyISAM tables which fills up the / (root) directory of the O/S as well.

MariaDB Enterprise Platform

The MariaDB Enterprise Platform is available on-premises and on the MariaDB SkySQL DBaaS (Cloud database platform). MariaDB Enterprise Platform consists of: