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Previous 30 Newer Entries Showing entries 61 to 90 of 649 Next 30 Older Entries

Displaying posts with tag: Replication (reset)

MySQL Utilities: copy, replicate, show, failover… over and over again.
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So, after installing Workbench 6.0.7 on my pc, and playing around with the MySQL Utilities that are included, I thought I’d do similar to what others have done (Thanks Tony D.) and share my experience on how I’ve used them. If you haven’t installed Workbench before, you might want to check your platform first: http://www.mysql.com/support/supportedplatforms/workbench.html (http://www.mysql.com/support/supportedplatforms/workbench.html).

So, even if you’re not using any of the recent versions and editions of Workbench (Utilities comes with all of them, Tools menu -> “Start Shell for MySQL Utilities“) you can

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MySQL Utilities: copy, replicate, show, failover… over and over again.
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So, after installing Workbench 6.0.7 on my pc, and playing around with the MySQL Utilities that are included, I thought I’d do similar to what others have done (Thanks Tony D.) and share my experience on how I’ve used them. If you haven’t installed Workbench before, you might want to check your platform first: http://www.mysql.com/support/supportedplatforms/workbench.html (http://www.mysql.com/support/supportedplatforms/workbench.html).

So, even if you’re not using any of the recent versions and editions of Workbench (Utilities comes with all of them, Tools menu -> “Start Shell for MySQL Utilities“) you can

  [Read more...]
The importance of multi source replication
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One of the latest labs releases of Oracle MySQL brings multi source replication. This lifts the limitation found in earlier releases that a MySQL slave can only have one master.

To be fair, there were other ways of doing this already:
There are many good uses of multi source replication. You could use it to combine data from multiple shards or applications.

If MySQL is used with a loadbalancer the most easy




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How to: Using Replication & Load balancing with Connector/NET
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Connector/NET 6.7 provides replication & load balancing configuration that allows to connect to master/slaves environments and at the same time balancing the request over all the available server in this scenario. This post will show you how to configure and use these new features on a console application.
Parallel replication: off by one
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One of the most common errors in development is where a loop or a retrieval by index falls short or long by one unit, usually because of an oversight or a logic in coding.

Of the following snippets, which one will run 10 times?

/* #1 */    for (N = 0 ; N < 10; N++) printf("%d\n", N);

/* #2 */ for (N = 0 ; N <= 10; N++) printf("%d\n", N);

/* #3 */ for (N = 1 ; N <= 10; N++) printf("%d\n", N);

/* #4 */ for (N = 1 ; N < 10; N++) printf("%d\n", N);

The question is deceptive, as there are two snippets that will run 10 times (1 and 3). But they will print different numbers. If you ware aiming for numbers from 1 to 10, only #3 is good.

After many years of programming, off-by-one errors are rare in my code, and I have been able to spot








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Continuent Tungsten 2.0.1 is now available
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The new Continuent Tungsten 2.0.1 is now available. Continuent Tungsten 2.0.1 is the first generally available release of Continuent Tungsten 2.0, which offers major improvements to Continuent's industry-leading database-as-a-service offering.  New features: Replication Provides low-impact, real-time replication with up-to 5X throughput over native MySQL and over 100X reduction in
Multi-master support in MySQL Connector/Java
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MySQL Connector/Java has long had support for replication-aware deployment, allowing a single logical Connection object to effectively “pool” connections to both a master and (potentially multiple) slaves.  This allowed scale-out of read load by distribution of read traffic to slaves, while routing write load to the master.  The JDBC specification provides a nice hook to know what’s read-only traffic – Connection.setReadOnly().  When a boolean value of true is passed, a ReplicationConnection will route further commands a selected slave instance, while values of false trigger routing to the master. 

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MySQL Fabric with MariaDB Galera Cluster ?
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MySQL Fabric is a very promising sharding framework. If I take Ulf Wendel definition of MySQL Fabric :

MySQL Fabric is an administration tool to build large “farms” of MySQL servers. In its most basic form, a farm is a collection of MySQL Replication clusters. In its most advanced form, a farm is a collection of [...]

MySQL 5.6 New Replication Features: Webinar followup Q&A
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I want to thank all attendees of my webinar, “MySQL 5.6 New Replication Features: Benefits, Challenges and Limitations“. We had questions that I didn’t have the time to answer:

Q: If I run on Amazon’s RDS, do I need to worry about enabling crash-safe slaves, or is that already in place?

A: Crash-safe replication is already configured for read replicas using MySQL 5.6.

Q: How the relay log purge will manage in case of

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MySQL 5.6’s new replication features: Benefits, Limitations and Challenges
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On Wednesday I’ll be leading a webinar exploring MySQL 5.6’s new replication features. And yes, as usual I’ll deliver news on the good, the bad and the ugly (that is to say the benefits, limitations and challenges).

The webinar, appropriately titled, “New Replication Features in MySQL 5.6: Benefits, Limitations, and Challenges“, is scheduled for Oct. 23 at 10 a.m. Pacific Daylight Time. You can

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Measuring Max Replication Throughput on Percona XtraDB Cluster with wsrep_desync
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Checking throughput with async MySQL replication

Replication throughput is the measure of just how fast the slaves can apply replication (at least by my definition).  In MySQL async replication this is important to know because the single-threaded apply nature of async replication can be a write performance bottleneck.  In a production system, we can tell how fast the slave is currently running (applying writes), and we might have historical data to check for the most throughput ever seen, but that doesn’t give us a solid way of determining where we stand right NOW().

An old consulting trick to answer this question is to simply stop replicating on your slave for a minute, (usually just the SQL_THREAD), restart it and watch how long it takes to catch up.  We can also watch the slave thread apply rate during this interval

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MySQL Replication Filters: replicate-ignore-table & ON DELETE CASCADE
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It's no secret that you shouldn't rely on replication filtering. Recently a customer asked if an `ON DELETE CASCADE` would still affect the data on a slave if the table was being ignored through replication filtering. It was one of those occasions that I couldn't give a confident answer without a quick test but alas the gut was right and the obvious answer is yes, "ON DELETE|UPDATE CASCADE" will change data even if you replicate using replication filters.

I tested using RBR and SBR. If anything I was questioning the behaviour of RBR here but it turns out to be consistent with SBR. I had a master-slave setup already deployed for some other testing so it was easy to implement the FKs needed for this. The dataset is the trusty world db available from dev.mysql.com and I needed to change the constraints on the

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Join Those Adopting the MySQL 5.6 Database
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MySQL Server 5.6 has seen fast adoption - the list of performance improvements and features make a convincing argument all on their own.

Join those adopting the MySQL database by taking the MySQL for Database Administrators training course.

This 5-day course teaches you all the core dba skills including what MySQL Server 5.6 brings you in terms of Replication (http://www.mysql.com/products/enterprise/replication.html). You will learn about:

  • Managing the MySQL Binary Log
  • MySQL replication threads and files
  • Using MySQL Utilities for Replication
  • Designing Complex Replication Topologies
  • Multi-Master and
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Tungsten Replicator Filters: A trove of golden secrets unveiled
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Since I joined the company in late 2010, I have known that one of the strong points of Tungsten Replicator is its ability of setting filters. The amazing capabilities offered by Tungsten filters cannot be fully grasped unless we explain how stage replication works.

There are several default stages in the replication stream. Every stage has an extraction task and an apply task. The extraction task will get data from the previous step repository and the apply task will save the data to the next repository, which can be either a temporary storage (memory queue, THL file) or the final destination (slave database server). Consider that the architecture allows developers to add stages, and you will appreciate its full power. For every stage, we can

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Multi-Source Replication with MySQL 5.7 – example
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Complementing this previous post, today we are going to configure 1 slave receiving updates from 2 master with Multi-source replication.
As mention before, this feature is only available on labs.mysql.com.

To configure it, is very simple, we are going to nees 2 masters with GTID enabled (see this post to know how to configure) and a slave with crash save options enabled.

Master 1 e 2:

gtid-mode=on
enforce-gtid-consistency

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MySQL Multi Source Replication
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Last week, durring MySQL Connect, MySQL 5.7.2 DMR was launched, one of the new functionality is the multi source replication. At the moment, MySQL can have only one master per slave (you can archive multi source replication via some hacks, but like the name says, it’s a hack).

See how to configure here

To clarify, there is a difference between multi-master replication and multi source replication, see the bellow pictures to understand the difference:

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MySQL 5.7.2 : Good job Oracle! (Well, almost)
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On September 21st, during the opening keynote at MySQL Connect 2013, Tomas Ulin disclosed the release of MySQL 5.7.2. This is a milestone release that includes several new features. Unlike the Previous one, which was just a point of pride, where Oracle was stating its continuous commitment to releasing new versions of MySQL. In MySQL 5.7.2, we see several new features:

  • First and foremost, performance. The announcement slides say MySQL 5.7.2 is 95% faster than MySQL 5.6 and 172% faster than MySQL 5.5. I don’t know yet in which circumstances these numbers hold true, but I am sure someone at Percona will soon prove or disprove the claim.
  • Performance Schema tables for several aspects:
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Building a Geo-Distributed CMS-backed site on a Budget (Poor Man’s CDN)
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Many CMS-backed sites are built using MySQL and are launched on cloud infrastructure. In order to mitigate down-time due to regional outages, it is advisable to create a geo-distributed redundancy topology in both the app layer as well as within the database. GenieDB makes it very easy to set up multiple MySQL database servers around the world that are automatically kept synchronized as data is changed on any of the nodes. The database nodes are typically paired 1-on-1 with an app or web server. Some of our customers use the app servers to dish out their CMS backed sites. The database is kept synchronized, but the customers still need to find a way to keep the media content that they use to be available on all these app/web servers. Below is a simple setup that can be easily configured within a very small budget and provides high availability

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Tips to Build a Fault-tolerant Database Application
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Applications should be written taking into account that errors will eventually happen and, in particular, database application developers usually consider this while writing their applications.

Although the concepts required to write such applications are commonly taught in database courses and to some extent are widely spread, building a reliable and fault-tolerant database application is still not an easy task and hides some pitfalls that we intend to highlight in this post with a set of suggestions or tips.

In what follows, we consider that the execution flow in a database application is characterized by two distinct phases: connection and business logic. In the connection phase, the application connects to a database, sets up the environment and passes the control to the business logic phases. In this phase, it gets inputs



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Writing a Fault-tolerant Database Application using MySQL Fabric
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In this post, we are going to show how to develop fault-tolerant applications using MySQL Fabric, or simply Fabric, which is an approach to building high availability sharding solutions for MySQL and that has recently become available for download as a labs release (http://labs.mysql.com/). We are going to focus on Fabric's high availability aspects but to find out more on sharding readers may check out the following blog post:

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It's all about bugs fixed: MySQL 5.6.14
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Most of MySQL gurus and famous users are probably in San Francisco now, getting ready for fun at MySQL Connect. Part of that fun should come from the announcement of great new MySQL 5.6.14 release (that somewhat silently happened yesterday).

I am sitting at home though and I've seen at best 3 sunny days in September. The rest of the time it rains, so hardly I can do anything more funny and useful than review of MySQL bug reports even during my weekend. Let me try to tell you what MySQL 5.6.14 is really about and what you should expect from it based on the list of bugs fixed. Please, do not blame me if my summary would be different from the upcoming keynotes at MySQL Connect. It rains here...


I'll use good old approach of checking my older posts




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Failover Techniques for MySQL
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The occurrence of failures and crashes can compromise the high availability of your database system affecting your revenue and reputation. Therefore, it is fundamental to minimize downtime and have an efficient strategy for crash recovery.

Replication and failover are commonly applied to deal with those situations. However, other types of failures can also affect the recovery process. In fact, the occurrence of unanticipated faults can really be an headache! Thus, it is better to be prepared and implement a good fault-tolerant failover strategy.

Performing failover is not trivial. It requires the execution of several steps in order to ensure data consistency (i.e., no data loss) -- especially if the "best" candidate to become the new master is not the most up-to-date.

Note that, one might desire that the slave with the best hardware





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5 reasons why MySQL replication lag is flapping between 0 and XXXXX
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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 to note the 5 different scenarios and symptoms of this – some are obvious and some are not really.

1. Duplicate server-ids on two or more slaves.

Symptoms: MySQL error log on a slave shows the slave thread is connecting/disconnecting from a master constantly.
Solution: check whether all nodes in the replication have unique

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MySQL Cluster Asynchronous Replication – conflict detection & resolution
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I was rooting through past blog entries and I stumbled accross a draft post on setting up multi-master (update anywhere) asynchronous replication for MySQL Cluster. The post never quite got finished and published and while the material is now 4 years old it may still be helpfull to some and so I’m posting it now. Note that a lot has happened with MySQL Cluster in the last 4 years and in this area, the most notable change has been the Enhanced conflict resolution with MySQL Cluster active-active replication feature introduced in MySQL Cluster 7.2 and if you’re only dealing with a pair of Clusters, that’s your best option as it removed the need for you

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Shi...pment happens - Tungsten Replicator 2.1.2
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It was just a few days ago that we announced, with celebratory enthusiasm, Tungsten Replicator 2.1.1, and today we are at it again, with Tungsten Replicator 2.1.2.

What happened? In a surfeit of overconfidence, we released Tungsten 2.1.1, with faith on the test suite and its result. The faith was justified, as the test suite was able to catch any known problem and regression. The overconfidence was unjustified, because, due to a series of unfortunate events, some sections of the test suite were accidentally disabled, and the regression that was lurking in the dark was not caught.

Therefore, instead of having a quiet post-release week-end, the whole team

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Going to MySQL Connect 2013
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MySQL Connect 2013 is coming up with several interesting new sessions. Some sessions that I am participating in got accepted for the conference, so if you are going there, you might find the following sessions interesting. For your convenience, the sessions have hCalendar markup, so it should be easier to add them to your calendar.

MySQL Sharding, Replication, and HA (September 21, 5:30-6:30pm in Imperial Ballroom B)

This session is an opportunity for you to meet the MySQL engineering team and discuss the latest tools and best practices for sharding MySQL across distributed





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Cloning MySQL 5.6 instances
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A tip for all those cloud users that like cloning database servers (as reported in my book Effective MySQL – Replication Techniques in Depth).

Starting with MySQL 5.6, MySQL instances have a UUID. Cloning servers to quickly create slaves will result in the following error message.

mysql> SHOW SLAVE STATUS\G
...
  Last_IO_Error: Fatal error: The slave I/O thread stops because master and slave have equal MySQL server UUIDs; these UUIDs must be different for replication to work.
...

The solution is simple. Clear our the file based configuration file (located in the MySQL datadir) and restart the MySQL instance.

$ rm -f /mysql/data/auto.cnf
$ service mysql restart
Tungsten-Replicator 2.1.1 with better installation and built-in security
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UPDATE 2013-08-30: Tungsten 2.1.2 was released.

UPDATE 2013-08-23: We have found a few problems that happen when replicating with RBR and temporal columns. We will have to publish an updated bugfix release quite soon.

Tungsten Replicator 2.1.1 is out. Key features in this release are:

  • A better installer, of which we have already given a preview in tpm, the multi-master composer. The new installer allows faster and more powerful deployments of both single and multiple masters topologies. And it also allows the next feature:
  • Secured communication layer. Now the replicator data and

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Using Continuent Tungsten to Survive MySQL Failures, at Percona University
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If you are in Washington DC area, don't miss Jeff Mace talk about using Continuent Tungsten to survive MySQL failures. Join us September 12, 2013 for Percona University in Washington, DC. This full-day event will provide you with deep insights into MySQL as well as an opportunity to network with the local MySQL community. The practical knowledge you'll receive will help you be more successful in
Third party solutions for master-master replication in MySQL
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Two of the more popular solutions are  MySQL Master HA and Percona Replication Manager. MySQL Master HA MHA is based on a set of Perl scripts that monitors for replication and server health. When a failover scenario will happen, it Continue reading →   [Read more...]
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