Category Archives: SQL

Temporary tables and MySQL STATUS information

When analysing MySQL configuration and status information at customers it is always interesting to see how the applications behave. This can partially be seen by the output of the SHOW GLOBAL STATUS command. See also Reading MySQL fingerprints. Today we … Continue reading

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Mirantis Training Blog: What’s the best architecture for multiple OpenStack component databases?

Welcome to Mirantis OpenStack Training’s monthly Q&A section. Here our instructors field questions about all aspects of OpenStack, and every month we’ll be sharing some of those answers with you here on the blog. If you have a question that you would … Continue reading

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MySQL spatial functionality – points of interest around me

This week I was preparing the exercises for our MySQL/MariaDB for Beginners training. One of the exercises of the training is about MySQL spatial (GIS) features. I always tell customers: „With these features you can answer questions like: Give me … Continue reading

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Why you should take care of MySQL data types

A customer reported last month that MySQL does a full table scan (FTS) if a query was filtered by a INT value on a VARCHAR column. First I told him that this is not true any more because MySQL has … Continue reading

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DOAG Datenbank Konferenz 2016

Heute war ich auf der DOAG Datenbank 2016 Konferenz in Düsseldorf. Der einzige Vortrag zum Thema MySQL war mein eigener: MySQL für Oracle DBAs. Daher hatte ich die Möglichkeit wieder mal etwas über den Zaun zu linsen. Hier meine Notizen: … Continue reading

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MariaDB 10.2 Window Function Examples

MariaDB 10.2 has introduced some Window Functions for analytical queries. See also: Window Functions, Window Functions, Window function and Rows and Range, Preceding and Following Function ROW_NUMBER() Simulate a row number (sequence) top 3 SELECT ROW_NUMBER() OVER (PARTITION BY NULL … Continue reading

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Galera Cache sizing

To synchronize the data between the Galera Cluster and a new or re-entering Galera node Galera Cluster uses 2 different mechanisms: For full synchronization of data: Snapshot State Transfer (SST). For delta synchronization of data: Incremental State Transfer (IST). The … Continue reading

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Max_used_connections per user/account

How many connections can be opened concurrently against my MySQL or MariaDB database can be configured and checked with the following command: SHOW GLOBAL VARIABLES LIKE ‚max_connections‘; +—————–+——-+ | Variable_name | Value | +—————–+——-+ | max_connections | 505 | +—————–+——-+ … Continue reading

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FromDual Backup Manager for MySQL 1.2.2 has been released

FromDual has the pleasure to announce the release of the new version 1.2.2 of the popular Backup Manager for MySQL and MariaDB (fromdual_bman). You can download the FromDual Backup Manager from here. In the inconceivable case that you find a … Continue reading

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Wir suchen Dich: MySQL/MariaDB DBA für FromDual Support

Wer sind wir? FromDual ist das führende unabhängige Beratungs- und Dienstleistungsunternehmen für MySQL, Galera Cluster, MariaDB und Percona Server in Europa mit Hauptsitz in der Schweiz. Unsere Kunden stammen hauptsächlich aus Europa und reichen vom kleinen Start-Up bis zur europäischen … Continue reading

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