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Displaying posts with tag: database (reset)
Multi Tb migration Using mydumper

In this post I will explain how to transfer a multi terabyte size database between two MySQL instances using mydumper, which is a logical backup and restore tool that works in parallel. I will also cover the case where you need to transfer only a subset of data.

Big tables are often problematic because of the amount of time needed to do mysqldump/restore which is single threaded. It is not uncommon for this type of process to take several days.

From MySQL 5.6 and on, we also have transportable tablespaces, but there are some limitations with that approach.

Physical backups (e.g. xtrabackup) have the advantage to be faster, but there are some scenarios where you still need/want a logical backup (e.g migrating to RDS/Aurora/Google Cloud SQL).

Steps Install mydumper/myloader

The first thing …

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Improving replication with multiple storage engines

New MariaDB/MySQL storage engines such as MyRocks and TokuDB have renewed interest in using engines other than InnoDB. This is great, but also presents new challenges. In this article, I will describe work that I am currently finishing, and which addresses one such challenge.

For example, the left bar in the figure shows what happens to MyRocks replication performance when used with a default install where the replication state table uses InnoDB. The middle bar shows the performance improvement from my patch.

Current MariaDB and MySQL replication uses tables to transactionally record the replication state (eg mysql.gtid_slave_pos). When non-InnoDB storage engines are introduced the question becomes: What engine should be used for the replication table? Any choice will penalise other engines heavily by injecting a cross-engine transaction with every replicated change. Unless all tables can be migrated to the …

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Getting to know MySQL InnoDB cluster, the new kid in the block

InnoDB Cluster was released as GA a few weeks ago. I remember the initial announcement of the product at OOW 2016, promising a seamless solution for replication and high availability with great ease of use. I was a bit disappointed to see that, at GA release time, the InnoDB Cluster is a patchwork of three separate products (Group Replication, MySQL Router, MySQL Shell) which the users have to collect and install separately.

Given this situation, I was very pleased when Matthew Lord published Docker-InnoDB-Cluster, an image for Docker that contains everything you need to get the system up and running. The …

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MySQL High Availability with Keepalived and HAProxy

In this blog post, we are going to test load balancer solution for MySQL high availability by integrating it with Keepalived, HAProxy, xinetd software components.

High availability databases use an architecture that is designed to continue to function normally even when there are hardware or network failures within the system.

Why we need this?

Let’s take a scenario where we have MySQL Multi-Master / MASTER-SLAVE replication setup for high availability. In the case of Hardware/Network failure on MASTER, In order to failover to a next available server, we need to manually do the configuration changes for client connections.In this case, downtime is expected since manual failover will take some times. To solve this we can integrate load balancer with MySQL to take care of this manual work and do automatic failover connections.

To avoid such downtimes and for the maximum high …

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Revisiting the hidden MySQL 8.0 data dictionary tables

A few months ago I wrote about showing the hidden tables in MySQL 8 data dictionary. What I presented there was a naïve solution, which I am now able to improve with a few (bold) moves. In the solution given in my previous article, I was able to guess the table names somehow, but they were still hidden from the catalog. I did not think clearly then. I should have used the data dictionary itself to see the tables. Here, in addition to getting the real list of tables, I offer a feature to unhide them permanently.

MySQL-Sandbox 3.2.08 has now the ability of un-hide the data dictionary tables, and keep them available for inspection. This feature came to my mind after a chat with the MySQL team during PerconaLive 2017. They stressed the …

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Basics of MySQL Administration and best practices

Following are the few best practices and basic commands for MySQL Administration.

MySQL Access and credential security

shell> mysql -u testuser -pMyP@ss0rd
mysql: [Warning] Using a password on the command line interface can be insecure.

By looking at OS cmd’s history using history cmd other os users can see/get MySQL user password easily. It always good to not use a password on the command line interface. Another option for securing password while automating MySQL scripts is a use of mysql_config_editor. For more info on this check out my blog post about credential security.

Consider of having following implementation for Strong access policy.

  • use of  validate_password plugin for a strong password policy.
  • Limit …
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MySQL 8.0 roles

One of the most interesting features introduced in MySQL 8.0 is roles or the ability of defining a set of privileges as a named role and then granting that set to one or more users. The main benefits are more clarity of privileges and ease of administration. Using roles we can assign the same set of privileges to several users, and eventually modify or revoke all privileges at once.

Roles in a nutshell

Looking at the manual, we see that using roles is a matter of several steps.

(1) Create a role. The statement is similar to CREATE USER though the effects are slightly different (we will see it in more detail later on.)

mysql …
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Dropping the Foreign Key Constraint Using pt-online-schema-change

In this blog post, we’ll look at how to get rid of the unused Foreign Key (FK) constraint and/or related columns/keys with the help of pt-online-schema-change and the power of its plugins.

Before we proceed, here is a useful blog post written by Peter Zaitsev on Hijacking Innodb Foreign Keys.

If you are trying to get rid of an unused foreign key (FK) constraint and related columns from versions older than MySQL 5.6, or tables that cannot be executed with

ALTER TABLE ... ALGORITHM=INPLACE

 because of limitations mentioned here (specifically, …

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Percona Blog Poll Results: What Programming Languages Are You Using for Backend Development?

In this blog we’ll look at the results from Percona’s blog poll on what programming languages you’re using for backend development.

Late last year we started a poll on what backend programming languages are being used by the open source community. The three components of the backend – server, application, and database – are what makes a website or application work. Below are the results of Percona’s poll on backend programming languages in use by the community:

Note: There is a poll embedded within this post, please visit the site to participate in this post's poll.

One of the best-known and earliest web service stacks is the LAMP stack, which spelled out refers to Linux, Apache, MySQL and PHP/Perl/Python. We can see that this early model is still popular when it comes to the backend.

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How does a relational database work

Introduction While doing my High-Performance Java Persistence training, I came to realize that it’s worth explaining how a relational database works, as otherwise, it is very difficult to grasp many transaction-related concepts like atomicity, durability, and checkpoints. In this post, I’m going to give a high-level explanation of how a relational database works internally while … Continue reading How does a relational database work →

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