We recently introduced 'mysqlrplsync' in MySQL Utilities release-1.4.2 RC. This new utility allows users to check the data consistency of an active replication system. In this blog we provide more details about how 'mysqlrplsync' works.

In an active replication topology, slaves may be slightly behind the master in processing events. Depending on the workload and capabilities of each slave, transactions may be applied at different times. Should this occur and something untoward happen to one of the slaves (such as a user making a manual change directly on the slave), a synchronization process may be required to ensure that the slaves have the same data - to manually catch up all of the slaves that are behind the master.

The strategy we choose was to build on the top of the replication process and makes use of GTIDs; it works independently of the binary log format (row, statement, or mixed) and does not create any new data …

Github user Adrianlzt provided a python-twisted alternative version of pyclustercheck per discussion on issue 7.

Due to sporadic performance issues noted with the original implementation in SimpleHTTPserver, the benchmarks which I’ve included as part of the project on github use mutli-mechanize library,

• cache time 1 sec
• 2 x 100 thread pools
• 60s ramp up time
• 600s total duration
• testing simulated node fail (always returns 503, rechecks mysql node on cache expiry)
• AMD FX(tm)-8350 Eight-Core Processor
• Intel 330 SSD
• local loop back test (127.0.0.1)

The SimpleHTTPServer instance faired as follows:

…

On Thursday 22nd May I’ll be hosting a webinar explaining how you can get the best from the NoSQL world while still getting all of the benefits of a proven RDBMS. As always the webinar is free but please register here.

There’s often a lot of excitement around NoSQL Data Stores with the promise of simple access patterns, flexible schemas, scalability and High Availability. The downside can come in the form of losing ACID transactions, consistency, flexible queries and data integrity checks. What if you could have the best of both worlds?

This webinar shows how MySQL Cluster provides simultaneous SQL and native NoSQL access to your data, with a simple key-value API (Memcached), REST, JavaScript, …

Percona has developed an Audit Log feature that is now included in Percona Server since the recent 5.5 and 5.6 releases. This implementation is alternative to the MySQL Enterprise Audit Log Plugin: Percona re-implemented the Audit Plugin code as GPL as Oracle’s code was closed source. This post is a quick introduction to this plugin.

Installation
There are two ways to install the Percona MySQL Audit Plugin:

INSTALL PLUGIN audit_log SONAME 'audit_log.so';

or in my.cnf

[mysqld]
plugin-load="audit_log=audit_log.so"

Verify installation

mysql> SHOW PLUGINS\G
...
*************************** 38. row ***************************
  Name: …

May 16, 2014 By Severalnines

We won’t bore you with buzzwords like volume, velocity and variety. This post is for MySQL users who want to get their hands dirty with Hadoop, so roll up your sleeves and prepare for work. Why would you ever want to move MySQL data into Hadoop? One good reason is archival and analytics. You might not want to delete old data, but rather move it into Hadoop and make it available for further analysis at a later stage. 

In this post, we are going to deploy a Hadoop Cluster and export data in bulk from a Galera Cluster using Apache Sqoop. Sqoop is a well-proven approach for bulk data loading from a relational database into Hadoop File System. There is also Hadoop Applier available from …

So I’ve submitted my talks for the Tech14 UK Oracle User Group conference which is in Liverpool this year. I’m not going to give away the topics, but you can imagine they are going to be about data translation and movement and how to get your various databases talking together.

I can also say, after having seen other submissions for talks this year (as I’m helping to judge), that the conference is shaping up to be very interesting. There’s a good spread of different topics this year, but I know from having talked to the organisers that they are looking for more submissions in the areas of Operating Systems, Engineered Systems and Development (mobile and cloud).

If you’ve got a paper, presentation, or idea for one that you think would be useful, …

New Continuent Tungsten Replicator 2.2.1 is now available for download at www.continuent.com/software and https://code.google.com/p/tungsten-replicator/wiki/Downloads?tm=2.Tungsten Replicator is a high performance, open source, data replication engine for MySQL and Oracle, released under a GPL V2 license. Tungsten Replicator has all the features you expect from enterprise-class data replication

Here comes the MySQL May Newsletter! As always it's packed with latest product news, technical articles, and not-to-be missed webinars and events where you'll get first-hand information directly from the MySQL experts at Oracle. The highlights in this edition include:

• Join Us at MySQL Central @ OpenWorld 2014
  
• Dr. Dobb's: NoSQL with MySQL
• Live Webinar: Upgrading to MySQL 5.6 - Best Practices
  
• Featured Video: MySQL for Excel Introduction
  
• Blog: Why VividCortex Uses MySQL
  
• Blog: Importing Raster-Based Spatial Data into MySQL 5.7
  

You can read it online or …

When the MySQL server receives a SELECT query, the query goes through several consecutive phases:

• parsing: SQL words are recognized, the query is split into different parts following the SQL grammar rules: a list of selected expressions, a list of tables to read, a WHERE condition, …
• resolution: the output of the parsing stage contains names of columns and names of tables. Resolution is about making sense out of this. For example, in “WHERE foo=3“, “foo” is a column name without a table name; by applying SQL name resolution rules, we discover the table who contains “foo” (it can be complicated if subqueries or outer joins are involved).
• optimization: finding the best way to read tables: the best order of tables, and for each table, the best way to access it (index lookup, index scan, …). The output …

In the MySQL team we are proposing to deprecate the COM_REFRESH packet in favor of specific queries to execute FLUSH commands. To provide a bit of context:

• The MySQL server protocol allows for clients to speak API commands via both a query and binary protocol interface. The set of the API commands can be seen in the MySQL Client/Server Protocol internals documentation, or very simply as they appear in a single switch statement:

  # ./sql/sql_parse.cc:1009 (simplified view)
  
    switch (command) {
  
    case COM_REGISTER_SLAVE:
    {
      /* do stuff */
      break;
    }
    case COM_QUERY:
    {
      /* parse query, do stuff */
      break;
    }
    case COM_REFRESH:
    {
     /* equivalent to running a FLUSH command */
      break;
    }
    case COM_SHUTDOWN:
    {
      kill_mysql();
      break;
    }
  }
  

• The historical advantage of having a binary …