Now that I'm back doing just database stuff, I've come to realize I've gotten a little sloppy about doing my homework.  Homework's never been my favorite thing in the world, but it often reduces stress when your under the gun during an outage or upgrade... We had a MySQL database server that's been slow on DML changes, and based on the slowest statements being 'COMMIT', we had a good mind

I configure all our master databases to use row-based binary logging where I work. In my opinion it is a much safer option than statement-based replication. The advantages and disadvantages of both types of MySQL replication are detailed in the online documentation here. You can't view the events a slave is applying directly with 'show processlist' but by issuing 'show open tables where in use' you can detect what table is receiving the attention of the SQL thread. If you need more information the mysqlbinlog command must be used to decode the slaves relay logs or masters binary logs.

Our developers often change a lot of rows with a single update statement. This usually results in some reasonable replication lag on downstream

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Got a packet bigger than ‘slave_max_allowed_packet’ bytes and binlog_format=STATEMENT|MIXED

Since version 5.1.64 MySQL introduces a new variable named slave_max_allowed_packet, which was introduced to allow large updates using row-based replication do not cause replication to fail when exceeded max_allowed_packet.

The problem is if you have you replication using binlog_format=STATEMENT or binlog_format=MIXED it ignores this option and use as limit for queries what is on max_allowed_packet variable but still reporting on slave_max_allowed_packet

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Switching roles

To get a taste of the power of Tungsten Replicator, we will show how to switch roles. This is a controlled operation (as opposed to fail-over), where we can decide when to switch and which nodes are involved.

In our topology, host1 is the master, and we have three slaves. We can either ask for a switch and let the script select the first available slave, or tell the script which slave should be promoted. The script will show us the steps needed to perform the operation.

IMPORTANT! Please note that this operation is not risk free. Tungsten replicator is a simple replication system, not a complete management tool like Continuent Tungsten. WIth the replicator, you must make sure that the applications have stopped writing to the master before starting the switch, and then you

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Intro

Tungsten Replicator is an open source tool that does high performance replication across database servers. It was designed to replace MySQL replication, although it also supports replication from and to Oracle and other systems. In this article, we will only cover MySQL replication, both simple and multi-master.

Preparing for installation

To follow the material in this article, you will need a recent build of Tungsten Replicator. You can get the latest ones from http://bit.ly/tr20_builds. In this article, we are using build 2.0.8-167.

Before starting any installation, you should make sure that you have satisfied all the prerequisites. Don't

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Read the original article at Why does MySQL replication fail?

When considering active-active multi-master, you must consider it’s foundation technology. Although MySQL replication is straightforward to setup, it can fail in a myriad of ways. Most of those are known and well understood. We can solve them only if we use the technology in the standard way. Click through to the end for multi-master solutions [...]

For more articles like these go to Sean Hull's Scalable Startups

Related posts:

5 Ways to fortify MySQL replication

Easy MySQL replication with

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Percona Live 2013 is coming up fast.  This is hands-down the best MySQL conference of the year, attended by a lot of people I really respect.  Check the speaker list if you need some of their names.  I will also be doing two talks myself.

• 9am Wednesday 24 April - Keynote:  How MySQL Can Thrive in the World of Massive Data Hype.  NoSQL solutions are oversold, but this is no reason for complacency in the MySQL community.  There are new challenges in data management, and we need to solve them or become irrelevant.   I will show some of the advances Continuent

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In the first part of this article we examined the types of conflicts and their causes. In this part, we will analyse some of the methods available to deal with conflicts.

Pessimistic locking (or: conflicts won't happen)

Applicability: synchronous clusters with 2pc

We've covered this topic in the previous article, but it's worth repeating. If you use a synchronous cluster, you don't have conflicts. For example, MySQL Cluster ensures consistent data with updates coming from different nodes. However, MySQL Cluster is not a replacement for a MySQL server, and it has severe limitations.

Optimistic locking

Applicability: synchronous clusters without 2pc (Galera)

Conflicting transactions proceed on different

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As alway with new technology there is always different approaches regarding the adoption. You can try to use the bleeding edge features or start with a very standard configuration. My personal advise to new users is to start with the most basic configuration.

This allow you to get familiar with the fundamentals : - how [...]

What is a conflict?

Readers of this blog know that one of my favorite tools, Tungsten Replicator, can easily create multi-master replication topologies, such as all-masters, star, fan-in. While this is good news for system designers and ambitious DBAs, it also brings some inconvenience. When you allow updates to happen in more than one master, you risk having conflicts. You may have heard this term before. For the sake of clarity, let's define what conflicts are, before analyzing each case in detail.

You have a conflict when several sources (masters) update concurrently the same data in asynchronous replication.

It's important to stress that this happens with asynchronous replication. In a truly synchronous cluster, where all data is kept consistent through

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The Percona Live MySQL Conference and Expo 2013 is almost 1 month away. It's time to start planning, set the expectations, and decide what to attend. This post will give a roundup of some of the sessions that I recommend attending and I look forward to.

First, the unexpected!

After much talk and disbelief, here they come! Oracle (http://www.mysql.com) engineers will participate to the Percona Live conference. This is wonderful! Their participation was requested by the organizers, by the attendees, and by community advocates, who all told the Oracle management how important it is to be in this conference. Finally, they have

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Stating the problem.

In my job, I do a lot of testing. And no matter how much organized we try to be, we end up with fewer machines than we would need to run all the tests that we want.

For some tasks, we can run MySQL Sandbox, and get the job done. But sometimes we need to make sure that applications and systems work well across the network, and we need to install and run systems on separate servers.

However, when you test replication systems, and every cluster takes three or four servers, you run our of available hosts very quickly. So you decide to use the clusters that are dedicated to automated testing to also run your own manual tests. Soon you realize that the tests that you are running manually are clashing with the automated ones, or with the ones that your colleagues are running.

A simple solution

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Intro

While working on one of the MySQL to Oracle replication projects for Continuent, I needed to implement an open-source utility for transforming MySQL schema to an Oracle dialect (DDL statements that create specific schema on Oracle) to save from otherwise tedious work. This article introduces ./ddlscan tool, which does that and is extensible to do much more.

Ingredients

Here's what you'll need:

• Your favorite DBMS with some tables. Currently supported MySQL, Oracle and PostgreSQL.
• Latest Tungsten Replicator build. Not even needed to install, enough to untar.
• Velocity template of your

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MySQL 5.6 is probably the version of MySQL with the biggest bundle of new features. You may want to try it soon, since it's now released as GA, and I would like to offer some practical experience on how to use some of the advanced features.

Since replication is my main interest, I will focus on some of the new features in this field, and I will compare what's available in MySQL 5.6 with Tungsten Replicator.

The focus of the comparison is usability, manageability, and some hidden functionality. Parallel replication has been available with Tungsten Replicator for almost two years, and Global Transaction Identifiers for much longer than that. With MySQL 5.6, it seems that the MySQL team wants to close the gap. While the main feature (parallel execution threads) is available and performing well, there are some

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Tungsten Replicator 2.0.7 was released today. In addition to a large number of bug fixes, this release adds several improvements for multi-master management, and support for Amazon RDS (as a slave).

While the Release Notes show a long list of improvements, I would like to focus on some of them that improve the handling of multi-master deployments.

When we released version 2.0.6, we added the first revision of the cookbook recipes in the build. That was still a green addition, which caused several bug reports. But since then, we have integrated the cookbook in our internal testing, making these recipes more robust and reliable. We are also planning to improve

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This article is the third in a series on data fabric design and introduces the fabric connector service design pattern.  The previous article in this series introduced the transactional data service design pattern, which defines individual data stores and is the building block for data fabrics based on SQL databases.  The fabric connector builds on transactional data services and is another basic building block of fabric architecture.

Description and Responsibilities
Fabric connectors make a collection of DBMS servers look like a single server.  The fabric connector presents what appears to be a data service API to applications.  It


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I am very excited and thrilled to use the latest release of MySQL 5.6 in production. This is probably the most notable and innovative release from many years, if not ever. During the last year, we had the chance to work with many new features and to test if fixes to old issues were working...