Monthly Archives - September 2013

5 reasons why MySQL replication lag is flapping between 0 and XXXXX

Working day to day with Percona Remote DBA customers, we have been facing an issue from time to time when MySQL replication lag is flapping between 0 and XXXXX constantly – i.e. Seconds_Behind_Master is 0 for a few secs, then it’s like 6287 or 25341, again 0 and so on. I would like […]

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Enabling crash-safe slaves with MySQL 5.6

Being able to configure slaves to be crash-safe is one of the major improvements of MySQL 5.6 with regards to replication. However we noticed confusion on how to enable this feature correctly, so let’s clarify how it should be done.
In short
1. Stop MySQL on slave
2. Add relay_log_info_repository = TABLE and relay_log_recovery = ON in […]

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MySQL webinar: ‘Introduction to open source column stores’

Join me Wednesday, September 18 at 10 a.m. PDT for an hour-long webinar where I will introduce the basic concepts behind column store technology. The webinar’s title is: “Introduction to open source column stores.”
What will be discussed?
This webinar will talk about Infobright, LucidDB, MonetDB, Hadoop (Impala) and other column stores

I will compare features between […]

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Percona Server 5.6-RC3 with TokuDB 7.0.4 – experimental build

While we are working hard on the final push of Percona Server 5.6 GA (I know that many people are waiting on this, but stay with us – we want to ensure that we have a quality release with great performance), I decided to make an experimental build of Percona Server 5.6 with the […]

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How to move the InnoDB log sequence number (LSN) forward

This post focuses on the problem of the InnoDB log sequence number being in the future.
Preface: What is an InnoDB log sequence number?
The Log sequence number (LSN) is an important database parameter used by InnoDB in many places.
The most important use is for crash recovery and buffer pool purge control.
Internally, the InnoDB LSN counter never […]

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TokuMX vs. MongoDB : In-Memory Sysbench Performance

In talking to existing MongoDB users and TokuMX evaluators, I’ve often heard that the performance of MongoDB is very good as long as your working data set fits in RAM. The story continues that if your working data set grows to be larger than the RAM on your server, the built-in sharding capabilities […]

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How InnoDB promotes UNIQUE constraints

The other day I was running pt-duplicate-key-checker on behalf of a customer and noticed some peculiar recommendations on an InnoDB table with an odd structure (no PRIMARY key, but multiple UNIQUE constraints). This got me thinking about how InnoDB promotes UNIQUE constraints to the role of PRIMARY KEYs. The documentation is pretty clear:
[DOCS]
When you […]

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September: A busy month for MySQL events

Now with summer winding down and school back in session, we get into a very busy time with many great opportunities to discover more about MySQL with several excellent MySQL events.
At first I wanted to cover all autumn events here but if I did that this post would be far too long. So instead I’m […]

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Introduction to Percona XtraBackup 2.1 (MySQL webinar & more)

Percona XtraBackup 2.1 has been in GA now for a little over four months and has some impressive new features to improve backup performance, security, and storage requirements. When used with Percona Server, additional features are enabled that can provide even more dramatic performance improvements.
Percona XtraBackup is open source, free MySQL hot backup software […]

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