We found a simple XA transaction that crashes MySQL 5.5 replication. This simple transaction inserts a row into an InnoDB table and a TokuDB table. The bug was caused by a flaw in the logging code exposed by the transaction’s use of two XA storage engines (TokuDB and InnoDB). This bug was fixed in the TokuDB 6.0.1 release.

Here are some details.  Suppose that a database contains the following tables.

create table t1 (a int) engine=InnoDB
create table t2 (a int) engine=TokuDB

 The following transaction

begin
insert into t1 values (1)
insert into t2 values (2)
commit

causes the replication slave to crash.

The crash occurs when mysqld tries to dereference a NULL pointer.

#4  0x000000000088e203 in MYSQL_BIN_LOG::log_and_order (this=0x14b8640, thd=0x7f7758000af0, xid=161, all=true, need_prepare_ordered=false, need_commit_ordered=true) at …

Read the original article at Accidental DBA’s Guide to MySQL Management

So you’ve been tasked with managing the MySQL databases in your environment, but you’re not sure where to start.  Here’s the quick & dirty guide. Oh yeah, and for those who love our stuff, take a look to your right. See that subscribe button? Grab our newsletter!

1. Installation

The “yum” tool is your friend.  If you’re using debian, you’ll use apt-get but it’s very similar. You can do a “yum list” to see what packages are available. We prefer to use the Percona distribution of MySQL.  It’s fully compatible with stock MySQL distribution, but usually a bit ahead in terms of tweak and fixes.  Also if you’re …

Intro

Oracle is widely use to support back-end systems.  On the other hand, MySQL is the "go-to" data management solution for the web-facing part of many businesses.  If you have both Oracle and MySQL in-house, you may already also have the need to share data between them.  In this article I'll describe software that my colleagues and I have been working on to move data from Oracle to MySQL in real-time without costing an arm and a leg.

Tungsten to the Rescue!

Latest Tungsten Replicator has many features, most of which are open-source, but the recent one for me is particularly exciting - thanks to the development done by my colleague Stephane Giron in the …

In my previous post I covered the shard-disk paradigm's pros and cons, but the conclusion that is that it cannot really qualify as a scale-out solution, when it comes to massive OLTP, big-data, big-sessions-count and mixture of reads and writes.

Read/Write splitting is achieved when numerous replicated database servers are used for reads. This way the system can scale to cope with increase in concurrent load. This solution qualifies as a scale-out solution as it allow expansion beyond the boundaries of one DB, DB machines are shared-nothing, can be added as a slave to the replication "group" when required.


And, as a fact, read/write …

From a Tumblr engineering blog post:

Tumblr is one of the largest users of MySQL on the web. At present, our data set consists of over 60 billion relational rows, adding up to 21 terabytes of unique relational data. Managing over 200 dedicated database servers can be a bit of a handful, so naturally we engineered some creative solutions to help automate our common processes.

Today, we’re happy to announce the open source release of Jetpants, Tumblr’s in-house toolchain for managing huge MySQL database topologies. Jetpants offers a command suite for easily cloning replicas, rebalancing shards, and performing master …

Once MySQL is deployed inside a datacenter environment (i.e. forms a cloud ;-), major feature in it becomes replication. It is used to maintain hot copies, standby copies, read-only copies, invalidate external systems, replicate to external systems, etc. If this functionality is broken, datacenter is broken – components are not synchronized anymore, invalidations not done, data not consistent.

From performance perspective, replication not working properly results in unusable slaves so load cannot be spread. This results in higher load on other machines, including master (especially on master, if environment needs stronger consistency guarantees).

Judging on replication importance in MySQL deployments, it should attract performance engineering as much as InnoDB and other critical pieces. Though slave replication performance is being increased in 5.6, master side is not (well, group commit may help a bit, but not as much).

…

MySQL and Continuent Tungsten at Constant Contact - How We Architected Our Replication StrategyThursday, June 14th10:00 am PDT/1:00 pm EDT19:00 CEST/18:00 BSTReserve your seat!Constant Contact is a provider of marketing services for over 500,000 small businesses and organizations worldwide, helping them to drive engagement and build relationships with current and prospective customers.As the

With the release of MySQL 5.6 binary log group commit is included, which is a feature focused on improving performance of a server when the binary log is enabled. In short, binary log group commit improve performance by grouping several writes to the binary log instead of writing them one by one, but let me digress a little on how transactions are logged to the binary log before going into the details. Before going into details about the problem and the implementation, let look at what you do to turn it on.

Nothing.

Well... we actually have a few options to tweak it, but nothing required to turn it on. It even works for existing engines since we did not have to extend the handlerton interface to implement the binary log group commit. However, InnoDB has some optimizations to take advantage of the binary log group commit implementation.

binlog_order_commits={0|1}

This is a …

As described in the first article of this series, Tungsten Replicator can replicate data from MySQL to Vertica in real-time.  We use a new batch loading feature that applies transactions to data warehouses in very large blocks using COPY or LOAD DATA INFILE commands.  This second and concluding article walks through the details of setting up and testing MySQL to Vertica replication.

To keep the article reasonably short, I assume that readers are conversant with MySQL, Tungsten, and Vertica.  Basic replication setup is not hard if you follow all the steps described here, but of course there are variations in every setup.  For more information on Tungsten check out the Tungsten Replicator project at code.google.com site well as …

Real-time analytics allow companies to react rapidly to changing business conditions.   Online ad services process click-through data to maximize ad impressions.  Retailers analyze sales patterns to identify micro-trends and move inventory to meet them.  The common theme is speed: moving lots of information without delay from operational systems to fast data warehouses that can feed reports back to users as quickly as possible.

Real-time data publishing is a classic example of a big data replication problem.  In this two-part article I will describe recent work on Tungsten Replicator to move data out of MySQL into Vertica at high speed with minimal load on DBMS servers.  This feature …