Databases, Systems & Networks

Introduction

In this tutorial, we will teach you how to scale up your WordPress MySQL database server setup using master-slave database replication and the HyperDB plugin for WordPress. Adding more database servers to your environment in this manner allows your WordPress application to read from multiple database servers, increasing read performance.

MySQL replication reaps the most performance benefits for a system that processes frequent reads and infrequent writes, like most WordPress installations. By using a single-master with multiple-slave setup, you can add more slaves to scale your system, until you run out of network bandwidth or your master cannot handle the update load. If you wish, you can add more than one slaves by repeating the “slave” portions of the replication sections of this tutorial.

We are assuming that your setup includes two load balanced WordPress application servers that connect to a separate MySQL database server (see the prerequisites for a tutorial on how to set that up). It is not strictly necessary to have load balanced application servers to follow this tutorial, but your MySQL database server should be separate from your application servers.

Prerequisites

Before continuing with this tutorial, you should have completed two tutorials or have a similar environment:

• How To Set Up a Remote Database to Optimize Site Performance with MySQL
• Optionally, How To Use HAProxy As A Layer 4 Load Balancer for WordPress Application Servers on Ubuntu 14.04

After following those tutorials, to set up WordPress with two load balanced web application servers and a separate database server, you should have four VPSs. Because we will be dealing with several VPSs, for reference purposes, we will call your four existing VPSs the following:

• haproxy-www: Your HAProxy server for layer 4 load balancing your WordPress web application servers. This is the entry point into your website
• wordpress-1: Your first WordPress web application server
• wordpress-2: Your second WordPress web application server
• mysql-1: Your MySQL server for WordPress

That is, your environment should look something like this:

In addition to your current environment, we will require one additional VPS during this tutorial. We will call it:

• mysql-2: Your slave MySQL database server

Lire la suite…

In order to log in to a MySQL server, you can run mysql command along with your login credentials and server’s IP address as arguments. For example:

$ mysql -u $MYSQL_ROOT -p $MYSQL_PASS -h 192.168.10.1

However, besides the inconvenience of typing extra arguments, using plain-text login credentials in a command line like above is really not a secure way to access a MySQL server. In a multi-user Linux environment, what you type in command line can easily be revealed to others who happen to run ps on the same host at the same time.

MySQL offers a way for you to log in to MySQL server without password, by using an external MySQL configuration file. In Linux, there are two different kinds of MySQL configuration files: (1) /etc/my.cnf and (2) ~/.my.conf. While any system-wide MySQL configuration is defined in /etc/my.cnf, any user-specific MySQL configuration is stored in ~/.my.cnf. You can leverage ~/.my.cnf, to define your MySQL login credential in the file.

$ vi ~/.my.cnf

[client]
user=alice
password=alice_passwd
host=192.168.10.1

Make sure to have the configuration file readable to you only.

$ chmod 0600 ~/.my.cnf

Once ~/.my.cnf is created, simply typing mysql command will let you log in to 192.168.10.1 as alice, and you no longer need to provide login password separately.

Source: Xmodulo

Introduction

ProxySQL is an open-source MySQL proxy server, meaning it serves as an intermediary between a MySQL server and the applications that access its databases. ProxySQL can improve performance by distributing traffic among a pool of multiple database servers and also improve availability by automatically failing over to a standby if one or more of the database servers fail.

In this guide, you will set up ProxySQL as a load balancer for multiple MySQL servers with automatic failover. As an example, this tutorial uses a multi-primary replicated cluster of three MySQL servers, but you can use a similar approach with other cluster configurations as well.

Prerequisites

To follow this tutorial, you will need:

• One Ubuntu 16.04 server set up with this initial Ubuntu 16.04 server setup tutorial, including a sudo non-root user and a firewall. This server will become your ProxySQL instance.
• Three MySQL servers configured to form a multi-primary replication group. You can set this up by following the How To Configure MySQL Group Replication on Ubuntu 16.04 tutorial. In the Choosing Single Primary or Multi-Primary section, follow the instructions for a multi-primary replication group.

Source: nixCraft

How do I use mysqldump command with Unix shell pipes?

The mysqldump client is a backup program which is used to dump a database or a collection of databases for backup or transfer to another SQL server (not necessarily a MySQL server). The dump typically contains SQL statements to create the table, populate it, or both. However, mysqldump can also be used to generate files in CSV, other delimited text, or XML format. The syntax is as follows to dump a database called foo to the remote server called server1.cyberciti.biz:

mysqldump db-name | mysql -h server1.dbsysnet.com db-name
mysqldump foo | mysql -h server1.dbsysnet.com foo

However, I recommend using VPN or ssh client to secure data transfer using the shell pipes as follows:

mysqldump db-name | ssh user@server1.dbsysnet.com mysql db-name
mysqldump -u vivek -p'myPassWord' foo | ssh vivek@server1.dbsysnet.com mysql -u backup -p'myPassword' bar