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Displaying posts with tag: Replication (reset)
On MySQL Replication Bugs

While writing about problematic Oracle MySQL features previously I concentrated mostly on InnoDB problems that I have to fight with really often and deliberately skipped replication from even the preliminary list of features to study in details for that blog post. First of all, I mostly work with MariaDB users now, and implementation of many replication features in MariaDB is notably different already (and has its own list of known problems). But this happened also because (asynchronous) replication plays a key role in most MySQL environments and deserves a detailed study in a separate post.

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[MySQL][replication]unknown error reading log event on the master

MySQL 5.7 and 8.0 have an issue of stopping replication on all slaves.

Unforeseen use case of my GTID work: replicating from AWS Aurora to Google CloudSQL

A colleague brought an article to my attention.  I did not see it on Planet MySQL where I get most of the MySQL news (or it did not catch my eye there).  As it is interesting replication stuff, I think it is important to bring it to the attention of the MySQL Community, so I am writing this short post.

The surprising part for me is that it uses my 4-year-old work for online migration to GTID

Multi-master with MariaDB 10 – a tutorial

The goal of this tutorial is to show you how to use multi-master to aggregate databases with the same name, but different data from different masters, on the same slave.

Example :

  • master1 => a French subsidiary
  • master2 => a British subsidiary

Both have the same database PRODUCTION but the data are totally different.

 

This screenshot is made from my own monitoring tool: PmaControl. You have to read 10.10.16.232 on master2 and not 10.10.16.235.
The fault of my admin system! :p)

We will start with three servers—2 masters and 1 slave—you can add more masters if needed. For this tutorial, I used Ubuntu 12.04. I’ll let you choose the right procedure for your distribution from Downloads.

Scenario

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Question about Semi-Synchronous Replication: the Answer with All the Details

I was recently asked a question by mail about MySQL Lossless Semi-Synchronous Replication. As I think the answer could benefit many people, I am answering it in a blog post. The answer brings us to the internals of transaction committing, of semi-synchronous replication, of MySQL (server) crash recovery, and of storage engine (InnoDB) crash recovery. I am also debunking some misconceptions that I have often seen and heard repeated by many. Let’s start by stating one of those misconceptions.

One of those misconceptions is the following (this is NOT true): semi-synchronous enabled slaves are always the most up-to-date slaves (again, this is NOT true). If you hear it yourself, then please call people out on it to avoid this spreading more. Even if some slaves have semi-synchronous replication disabled (I will use semi-sync for …

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How to setup a Replication User

 

A replication user is necessary to set up the relationship Primary/Replica. This is a short step but it needs a bit more of attention.

From the MySQL 5.7 documentation (highlights are my own):

Although you do not have to create an account specifically for replication, you should be aware that the replication user name and password are stored in plain text in the master info repository file or table (see Section 16.2.4.2, “Slave Status Logs”). Therefore, you may want to create a separate account that has privileges only for the replication process, to minimize the possibility of compromise to other accounts.

The following command specifically will allow replication from all databases and tables connecting from all hosts. For security reasons you may want to limit access to replication only to the IP address of the server doing the …

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On Fine MySQL Manual

Today I am going to provide some details on the last item in my list of problems with Oracle's way of MySQL server development, maintenance of MySQL Manual. I stated that:
"MySQL Manual still have many details missing and is not fixed fast enough.
Moreover, it is not open source...
"Let me explain the above:

  1. MySQL Reference Manual is not open source. It used to be built from DocBook XML sources. Probably that's still the case. But you can not find the source code in open repositories (please, correct me if I am wrong, I tried to search...) That's because it is NOT open source. It says this clearly in …
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Replication from Percona Server for MySQL to PostgreSQL using pg_chameleon

Replication is one of the well-known features that allows us to build an identical copy of a database. It is supported in almost every RDBMS. The advantages of replication may be huge, especially HA (High Availability) and load balancing. But what if we need to build replication between 2 heterogeneous databases like MySQL and PostgreSQL? Can we continuously replicate changes from a MySQL database to a PostgreSQL database? The answer to this question is pg_chameleon.

For replicating continuous changes, pg_chameleon uses the mysql-replication library to pull the row images from MySQL, which are transformed into a jsonb object. A pl/pgsql function in postgres decodes the jsonb and replays the changes into the postgres database. In order to setup this type of replication, your mysql binlog_format must be “ROW”.

A few points you should know before setting up this …

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Galera cluster to AWS Aurora migration & HA_ERR_FOUND_DUPP_KEY

In this post we will see a case study of a Galera Cluster migration to AWS Aurora and quick solution to the replication issue. A friend received an error in a Master-Master replication as follows: Could not execute Write_rows event on table _database._table; Duplicate entry '65eJ8RmzASppBuQD2Iz73AAy8gPKIEmP-2018-08-03 08:30:03' for key 'PRIMARY', Error_code: 1062; handler error HA_ERR_FOUND_DUPP_KEY; […]

Presentation:Evolution of MySQL Parallel Replication

MySQL replication has evolved a lot in 5.6 ,5.7 and 8.0. This presentation focus on the changes made in parallel replication. It covers MySQL 8.0. It was presented at Mydbops database meetup on 04-08-2016 in Bangalore.

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