I presented a talk at Percona Live Amsterdam a few weeks ago (simple recipes for your Galera cluster), and one of the topics was schema changes. I discussed the drawbacks and benefits of Total Order Isolation (TOI), Rolling Schema Upgrades (RSU) and pt-online-schema-change. One thing I forgot was …

The other day a colleague and friend of mine, Peter Boros, had a case where one of our clients had to track down the process shutting down MySQL. This blog is based on the discussion we had about that internally.

Our client wanted Peter to identify the culprit behind periodic shutdowns. This proved to be slightly more difficult than usual, for reasons that you might guess from the title of this blog.

Here is what Peter saw in the logs:

150928 15:15:33 [Note] /usr/sbin/mysqld: Normal shutdown
150928 15:15:36 [Note] Event Scheduler: Purging the queue. 0 events
150928 15:15:39 [Warning] /usr/sbin/mysqld: Forcing close of thread 411515  user: 'dashboard'
150928 15:15:40  InnoDB: Starting shutdown...
150928 15:15:59  InnoDB: Shutdown completed; log sequence number 4873840375
150928 15:16:00 [Note] /usr/sbin/mysqld: Shutdown …

Description:

I create a empty table and then alter this table's "AUTO_INCREMENT" starts from 10000000.After a long time ,MySQL lost "AUTO_INCREMENT" definition when I show this table again. MariaDB has the same problem but Percona Server is fine.

$mysql06

Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 141028725
Server version: 5.6.17-log MySQL Community Server (GPL)

Copyright (c) 2000, 2014, 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.

mysql> use test;
Reading table information for …

During the PerconaLive conference in Amsterdam, I attended a session where I heard a good piece of advice about using GTID. It amounts to: look at SHOW SLAVE STATUS output, and if you see more than one line in the Executed_Gtid_Set field, this tells you immediately if someone has written on a slave database.
This is good advice. Let's dissect it. Here is what a regular slave looks like, when nobody has messed up with it:

SHOW SLAVE STATUS\G
*************************** 1. row ***************************
 [...]
             Master_Server_Id: 1
                  Master_UUID: 00013454-1111-1111-1111-111111111111
             Master_Info_File: mysql.slave_master_info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: Slave has read all relay log; waiting for more …

What is Spark

Apache Spark is a cluster computing framework, similar to Apache Hadoop. Wikipedia has a great description of it:

Apache Spark is an open source cluster computing framework originally developed in the AMPLab at University of California, Berkeley but was later donated to the Apache Software Foundation where it remains today. In contrast to Hadoop’s two-stage disk-based MapReduce paradigm, Spark’s multi-stage in-memory primitives provides performance up to 100 times faster for certain applications. By allowing user programs to load data into a cluster’s memory and query it repeatedly, Spark is well-suited to machine learning algorithms.

In contrast to popular belief, Spark does not require all data to fit into memory but will use caching to speed up the operations …

Because somebody asked for it on Freenode:

CREATE FUNCTION DATE_TRUNC(field ENUM('microsecond', 'millisecond', 'second', 'minute', 'hour', 'day', 'week', 'month', 'quarter', 'year', 'decade', 'century', 'millennium'), source datetime(6))
RETURNS datetime(6)
DETERMINISTIC
BEGIN
  IF field IN ('millisecond') THEN SET source = source - INTERVAL MICROSECOND(source) % 1000 MICROSECOND; END IF;
  IF field NOT IN ('microsecond', 'millisecond') THEN SET source = source - INTERVAL MICROSECOND(source) MICROSECOND; END IF;
  IF field NOT IN ('microsecond', 'millisecond', 'second') THEN SET source = source - INTERVAL SECOND(source) SECOND; END IF;
  IF field NOT IN ('microsecond', 'millisecond', 'second', 'minute') THEN SET source = source - INTERVAL MINUTE(source) MINUTE; END IF;
  IF field NOT IN ('microsecond', 'millisecond', 'second', 'minute', 'hour') THEN SET source = source - INTERVAL HOUR(source) HOUR; END IF;
  IF field NOT IN ('microsecond', 'millisecond', 'second', …

Complimenting the expanded CREATE USER syntax introduced in MySQL Server 5.7.6 is more useful ALTER USER syntax. Before MySQL Server 5.7.6, ALTER USER could only be used to expire a user’s password. That’s pretty limited. With changes made in MySQL Server 5.7.6, a better distinction is made between privilege-level attributes (those which are managed via GRANT and REVOKE statements) and account-level attributes (those managed using CREATE USER and ALTER USER statements).…

We love developer conferences, they are informative, fun and a great way to network with like minded people. The sessions can help you and your organization discuss and address technology challenges, learn how others are solving problems and exchange knowledge. Even if you can’t make it, most of these conferences are streamed online. Here are the 5 DevOp conferences you should consider attending.

AWS re:Invent

The annual cloud conference, by market leaders themselves, is an event which is jam-packed and sold out, months before the actual event. Amazon Web Services (AWS) knows the importance of educating and constantly innovating on the cloud and encourages organizations to migrate their IT infrastructure to embrace the cloud. AWS re:Invent 2015 has a mammoth 313 sessions with 491 speakers. This event should top any DevOp’s list.

…

We love developer conferences, they are informative, fun and a great way to network with like minded people. The sessions can help you and your organization discuss and address technology challenges, learn how others are solving problems and exchange knowledge. Even if you can’t make it, most of these conferences are streamed online. Here are the 5 DevOp conferences you should consider attending.

AWS re:Invent

The annual cloud conference, by market leaders themselves, is an event which is jam-packed and sold out, months before the actual event. Amazon Web Services (AWS) knows the importance of educating and constantly innovating on the cloud and encourages organizations to migrate their IT infrastructure to embrace the cloud. AWS re:Invent 2015 has a mammoth 313 sessions with 491 speakers. This event should top any DevOp’s list.

…

Next week, all the MariaDB Server developers will descend to Amsterdam for the developer’s meeting. As you know the meeting is open to all interested parties, so we hope to see you in Amsterdam Tuesday Oct 13 – Thursday Oct 15. The schedule is now online as well.

In addition to that, Monday Oct 12 2015, there is also a meetup planned with the MySQL User Group NL. As the organiser Daniël van Eeden wrote, this is a one of a kind meetup: “This is a very unique event, it is not often possible to find so many MariaDB developers together and speaking about what they work on.”

Yes, we’re doing it lightning talk …