As a MySQL DBA I already know the data changes that happen on my system. I have logs for that.

However, it’s a common problem that several years into the life of an application, the current developers won’t know where in the codebase queries come from. It’s often hard for them to find the location in the code if queries are formed dynamically; the pattern I show them to optimize doesn’t match anything in the code.

I stumbled on a trick a couple years ago that has been invaluable in tracking down these problematic queries: query comments.

Here’s an example:

When a query generally shows up in a slow query log, it might look something like this:

# Time: 150217 10:26:01
# User@Host: comments[comments] @ localhost []  Id:    13
# Query_time: 0.000231  Lock_time: 0.000108 Rows_sent: 3  Rows_examined: 3
SET timestamp=1424186761;
select * from cars;

That logging shows me who executed the query …

#DBHangOps 02/19/15 -- Long Query Time, Operational TokuDB, and more!

Hello everybody!

Join in #DBHangOps this Thursday, February, 19, 2015 at 11:00am pacific (19:00 GMT), to participate in the discussion about:

• Learnings from operating TokuDB
• What's a good long_query_time?
• Testing your backups
• MySQL 5.7 defaults suggestions

You can check out the event page at https://plus.google.com/events/cohut2qncrbkrrmbs868kjorvbo on Thursday to participate.

As always, you can still watch the #DBHangOps twitter search, the @DBHangOps twitter feed, or this blog post to get a link for the google hangout on …

There were so many valuable articles already written by others over past years explaining all details about InnoDB transaction isolation modes and how to deal with this. So, I'll avoid to repeat what was already said ;-) -- my attention attracted the performance study made by PeterZ and published in the following article: http://www.percona.com/blog/2015/01/14/mysql-performance-implications-of-innodb-isolation-modes/ -- the article is very good and providing a good analyze of the observed problem which is solved by using READ-COMMITTED transaction isolation instead of REPEATABLE-READ (which is default in InnoDB).. The natural question is coming then: why don't we have then the READ-COMMITTED mode by default?.. Is there any danger?..

Let's then investigate together..

First of all, you should …

MySQL meets NoSQL with JSON UDF

I recently got back from FOSDEM, in Brussels, Belgium. While I was there I got to see a great talk by Sveta Smirnova, about her MySQL 5.7 Labs release JSON UDF functions. It is important to note that while the UDF come in a 5.7 release it is absolutely possible to compile and use the UDF with earlier versions of MySQL because the UDF interface has not changed for a long time. However, the UDF should still be considered alpha/preview level of quality and should not be used in production yet! For this example I am using Percona Server 5.6 with the UDF.

That being said, the proof-of-concept that I’m about to present here uses only one JSON function (JSON_EXTRACT) and it has worked well enough in my testing to present my idea here. The JSON functions will probably be GA sometime soon anyway, and this is a useful test of the JSON_EXTRACT function. …

Within the MySQL data directory, the InnoDB storage engine creates two types of files — the data files and the redo log files. Each data file (or ibd file) belongs to exactly one tablespace. Each tablespace is given a unique identifier called the space_id. One tablespace can have 1 or more data files. If a tablespace has more than one data file, then the data files have a specific order or sequence. The data files can be thought of as being concatenated to each other in that specific order.

The data file is made up of a series of equal sized pages. Each page in the data file is given a unique number identifier called the page number (page_no). The first page of the first ibd file is given the page_no of 0. The page number of the first page of the second ibd file of the tablespace is …

Taxonomy upgrade extras: MySQL Enterprise Monitormonitoringeventhandlermpmperformance monitor

MySQL Enterprise Monitor (MEM) has by default no Event Handlers created and activated. These Event Handlers you have to define yourself according to your needs.

In this article we discuss how to create MySQL Enterprise Monitor Event …

What kinds of aliveness/health checks should we build into Nagios? Which metrics should we monitor with thresholds to raise alarms, and what should the thresholds be? What graphs should we build of status counters, which graphs should we examine and what do they mean?

In this webinar, Baron Schwartz answers these database monitoring questions and more.

If you did not have a chance to join the webinar, the slide deck is embedded below. You can also register for a recording here.

[…] I am connecting following Andrews advice: Stackoverflow Link Also, Monitoring and Managing […]

First things first: I could use this title for every year, it is an evergreen. In order for this title to make sense, there must be a specific context and in this case the context is Big Data. We have seen new ideas and many announcements in 2014, and in 2015 those ideas will shape up and early versions of innovative products will start flourishing. Like many other people, I prepared some comments and opinions to post back in early January then, soon after the season’s break, I started flying around the world and the daily routine kept me away from the blog for some time. So, as a good last blogger, it may be time for me to post my own predictions, for the joy of my usual 25 readers. Small Data, Big Data, Any Data The term Big Data is often misused. Many different architectures, objectives, projects and issues deviate from its initial meaning. Everything today seems to be “Big Data” – whether you collect structured or …

This Log Buffer Edition sheds light at some of the nifty blog post of the week from Oracle, SQL Server and MySQL.

Oracle:

Patch Set Update: Hyperion Data Relationship Management 11.1.2.3.504

The Hitchhiker’s Guide to the EXPLAIN PLAN Part 33: The mother of all SQL antipatterns?

MongoDB as a Glassfish Security Realm

E-Business Suite customers must ensure that their database remains on a level that is covered by Error Correction Support (ECS)

…