MySQL Replication HOL v2Title MySQL Replication HOL v2.ppt Author Wei-Chen Chiu Created Date 3/6/2013 6:38:10 AM

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MySQL Hands-On Lab:

Getting Started with MySQL Replication

Sven Sandberg, Luis Soares MySQL Replication Team

Presented by Ben Krug Senior MySQL Support Engineer


The following is intended to outline our general product direction. It is intended for information purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described for Oracle’s products remains at the sole discretion of Oracle.


Agenda

  Replication Basics   Hands on Exercises to Set Up MySQL Replication   More Resources


Replication Basics

 MySQL Master Server -  Changes data

-  Logs changes (Events) into a file (Binary Log)

 MySQL Slave Server

-  Retrieves events from the master

-  Replays the events on the slave's databases

MySQL Replication Components


Replication Basics

 The Binary Log -  File based log that records the changes on the master.

-  Statement or Row based format (may be intermixed).

-  Split into transactional groups.

BEGIN ... Ev1 Ev2 COMMIT

MySQL Replication Components: Binary Log

BEGIN ... Ev1 Ev2 COMMIT

Event Layout on a Binary Log File


Replication Basics MySQL Replication Components: Binary Log

Binary Log

Binary log files

Index

Under the Hood Binary log files: mysql-bin.000001, mysql-bin.000002, …

- The actual data.

Index: mysql-bin.index

- An index over the binary log files.

Log coordinate:

- binlog file name + event offset in the file (3.23.15+)

- Global Transaction Identifiers (5.6+)


Session Dump

Binary log

I/O SQL

Relay log

Slave Master

Session Session

Replication Basics MySQL Replication Architecture

Master

info

Relay log info

  I/O and SQL Thread Replication Metadata is stored in files.  Starting in MySQL 5.6 the Metadata can be stored in tables.


Replication Basics

 Asynchronous Replication (MySQL 3.23.15+) -  Transactions are committed and externalized without interaction with

the replication layer.

-  Events are sent to slave after the commit operation is acknowledged.

-  Faster but vulnerable to lost updates on server crashes and inconsistency.

-  Built into the server.

  Semi-synchronous Replication (MySQL 5.5+)

-  Master commits transaction but waits until one slave acknowledges having received and stored the event before replying to the client.

Changes Propagation


Replication Basics

Hands-On


Replication Basics Getting MySQL

 Head to -  http://dev.mysql.com

  ... and get the latest MySQL 5.6 generic tar.gz package from there

 … or alternatively, you can find MySQL 5.6.6 linux generic package at your local directory /opt/ .


Replication Basics Getting MySQL

$ tar xfvz /opt/mysql-....tar.gz --directory=$HOME/rephol

$ mkdir $HOME/rephol/ $ cd $HOME/rephol/

Create a directory for storing the binaries (e.g., under your home).

Unpack the package (e.g., using tar).

$ mv $HOME/rephol/mysql-... $HOME/rephol/mysql-5.6

Rename the directory for simplicity


Replication Basics Setting Up MySQL

$ mysql_install_db --basedir=/usr/ --datadir=$HOME/rephol/master --user=`whoami`

Create Two Data Directories

$ mysql_install_db --basedir=/usr/ --datadir=$HOME/rephol/slave --user=`whoami`

Create two Data

Directories


Replication Basics Setting Up MySQL Master Server

[mysqld] server-id=1 log-bin=master-bin log-error=master.err port=12000 socket=/tmp/master.sock

Create a defaults file called $HOME/rephol/master.cnf

Set the unique server id.

Turn ON the binary log.


Replication Basics

$ mysqld --defaults-file=$HOME/rephol/master.cnf --lc-messages-dir=/usr/share/mysql --datadir=$HOME/rephol/master/

Start the master server.

$ mysql -u root --port 12000 --protocol=tcp --prompt='master> '

Log in to the master server.

Setting Up MySQL Master Server


Replication Basics Inspecting the Master Status

master> SHOW BINARY LOGS; ... master> SHOW BINLOG EVENTS; ... master> SHOW MASTER STATUS;

What binlog files are in use?

What's in the first binary log?

What binary log is in use what is its position?


master> SHOW BINARY LOGS;

master> SHOW BINLOG EVENTS;

master> SHOW MASTER STATUS;

Replication Basics Inspecting the Master Status

+-------------------+----------+--------------+------------------+-------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set | +-------------------+----------+--------------+------------------+-------------------+ | master-bin.000001 | 120 | | | | +-------------------+----------+--------------+------------------+-------------------+ 1 row in set (0.00 sec)

+-------------------+-----+-------------+-----------+-------------+-----------------------------------------+ | Log_name | Pos | Event_type | Server_id | End_log_pos | Info | +-------------------+-----+-------------+-----------+-------------+-----------------------------------------+ | master-bin.000001 | 4 | Format_desc | 1 | 120 | Server ver: 5.6.6-m9-log, Binlog ver: 4 | +-------------------+-----+-------------+-----------+-------------+-----------------------------------------+ 1 row in set (0.00 sec)

+-------------------+-----------+ | Log_name | File_size | +-------------------+-----------+ | master-bin.000001 | 120 | +-------------------+-----------+ 1 row in set (0.00 sec)


Replication Basics Binary Log Layout

Log Events

Format description

Rotate

Log Events

Format description

Rotate

Log Events

Format description   Multiple Files.

  Files begin with Format Description event.

  Each log file ends with a Rotate event.


Replication Basics Setting Up Replication User (that the slave will connect to the master with)

master> CREATE USER `rpl_user`@`localhost`; master> GRANT REPLICATION SLAVE ON *.* TO `rpl_user`@`localhost` IDENTIFIED BY 'secret'; master> FLUSH PRIVILEGES;

We could use any user.

Needs replication grants to read any change

on the master

Better use a dedicated

user for connecting the slave.


Replication Basics Setting Up MySQL Slave Server

[mysqld] server-id=2 relay-log=slave-relay-bin log-error=slave.err port=12001 socket=/tmp/slave.sock

Set the unique server id.

Set the name for the relay log.

Create a defaults file called $HOME/rephol/slave.cnf


Replication Basics Starting Up The MySQL Slave Server

$ mysqld --defaults-file=$HOME/rephol/slave.cnf --lc-messages-dir=/usr/share/mysql --datadir=$HOME/rephol/slave/

Start the slave server.

$ mysql -u root --port 12001 --protocol=tcp --prompt='slave> '

Log in to the slave server.


Replication Basics Starting the Slave Threads.

slave> CHANGE MASTER TO MASTER_HOST = 'localhost', MASTER_PORT = 12000, MASTER_USER = 'rpl_user', MASTER_PASSWORD = 'secret';

Point the slave server to the master

server.

Use the credentials we had granted

before.

slave> START SLAVE; Start the slave

threads.


Replication Basics Inspecting the Slave Status

slave> SHOW SLAVE STATUS\G

Inspect the slave status.

(...) Slave_IO_State: Waiting for master to send event Master_Host: localhost Master_User: rpl_user Master_Port: 12000 Connect_Retry: 60 Master_Log_File: master-bin.000002 Read_Master_Log_Pos: 120 Relay_Log_File: slave-relay-bin.000003 Relay_Log_Pos: 284 Relay_Master_Log_File: master-bin.000002 Slave_IO_Running: Yes Slave_SQL_Running: Yes (...)

Both slave threads are up and running!


Replication Basics Replicating From Master to Slave.

master> USE test; master> CREATE TABLE t1 (a INT); slave> USE test; slave> SHOW TABLES; master> INSERT INTO t1 VALUES(1); slave> SELECT * FROM t1;

Use the test db.

Create a table.

Slave has replicated the table.

Slave has replicated the data.


Replication Basics What's in the Binary Log?

master> SHOW BINLOG EVENTS [IN 'master-bin.0000002'];

+-------------------+-----+-------------+-----------+-------------+-----------------------------------------+ | Log_name | Pos | Event_type | Server_id | End_log_pos | Info | +-------------------+-----+-------------+-----------+-------------+-----------------------------------------+ | master-bin.000002 | 4 | Format_desc | 1 | 120 | Server ver: 5.6.6-m9-log, Binlog ver: 4 | | master-bin.000002 | 120 | Query | 1 | 217 | use `test`; CREATE TABLE t1 (a INT) | | master-bin.000002 | 217 | Query | 1 | 296 | BEGIN | | master-bin.000002 | 296 | Query | 1 | 395 | use `test`; INSERT INTO t1 VALUES (1) | | master-bin.000002 | 395 | Xid | 1 | 426 | COMMIT /* xid=21 */ | +-------------------+-----+-------------+-----------+-------------+-----------------------------------------+ 5 rows in set (0.00 sec)

The “CREATE TABLE” statement.

The “INSERT” statement.


Replication Basics Replicating From Master to Slave – binary log formats.

•  Three formats: -  Statement – every change logged as a statement.

  Reexecuted on the slave. -  Row – every change logged as data.

  Data changes are applied on the slave. -  MIXED – every change logged either as data or statements.

  Automatically switches from statement to row on non-deterministic statements.


Replication Basics Replicating From Master to Slave – binary log formats.

master> set binlog_format=ROW; master> INSERT INTO t1 VALUES(2); master> SHOW BINLOG EVENTS; +-------------------+-----+-------------+-----------+-------------+-----------------------------------------+ | Log_name | Pos | Event_type | Server_id | End_log_pos | Info | +-------------------+-----+-------------+-----------+-------------+-----------------------------------------+ | master-bin.000002 | 4 | Format_desc | 1 | 120 | Server ver: 5.6.6-m9-log, Binlog ver: 4 | | master-bin.000002 | 120 | Query | 1 | 217 | use `test`; CREATE TABLE t1 (a INT) | | master-bin.000002 | 217 | Query | 1 | 296 | BEGIN | | master-bin.000002 | 296 | Query | 1 | 395 | use `test`; INSERT INTO t1 VALUES (1) | | master-bin.000002 | 395 | Xid | 1 | 426 | COMMIT /* xid=21 */ | | master-bin.000002 | 426 | Query | 1 | 498 | BEGIN | | master-bin.000002 | 498 | Table_map | 1 | 543 | table_id: 70 (test.t1) | | master-bin.000002 | 543 | Write_rows | 1 | 583 | table_id: 70 flags: STMT_END_F | | master-bin.000002 | 583 | Xid | 1 | 614 | COMMIT /* xid=27 */ | +-------------------+-----+-------------+-----------+-------------+-----------------------------------------+ 9 rows in set (0.00 sec)

Let's change the format.

The second “INSERT” statement.


Replication Basics Master replication files.

$ ls -la master/

(...) -rw-rw---- 1 XXXXXX XXXXXX 143 Sep 26 11:10 master-bin.000001 -rw-rw---- 1 XXXXXX XXXXXX 614 Sep 26 11:40 master-bin.000002 -rw-rw---- 1 XXXXXX XXXXXX 40 Sep 26 11:10 master-bin.index (...)

The binary log files.

Index file over the existing binary log files.


Replication Basics Slave replication files.

$ ls -la slave/

(...) -rw-rw---- 1 XXXXXXX XXXXXXX 128 Sep 26 11:40 master.info (...) -rw-rw---- 1 XXXXXXX XXXXXXX 57 Sep 26 11:40 relay-log.info (...) -rw-rw---- 1 XXXXXXX XXXXXXX 337 Sep 26 11:10 slave-relay-bin.000002 -rw-rw---- 1 XXXXXXX XXXXXXX 778 Sep 26 11:40 slave-relay-bin.000003 -rw-rw---- 1 XXXXXXX XXXXXXX 50 Sep 26 11:10 slave-relay-bin.index (...)

The relay log files.

Index file over the existing binary log files.

Persists IO thread replication metadata (master host, username, … and positioning on the master's binlog).

Persists SQL thread replication metadata. Basically, the positioning in the relay log.


More Resources   White Paper: MySQL Replication: An Introduction http://www.mysql.com/why-mysql/white-papers/mysql-replication-introduction/   White Paper: MySQL Replication Tutorial: Configuration, Provisioning and

Management http://www.mysql.com/why-mysql/white-papers/mysql-replication-tutorial/   Documentation: Replication http://dev.mysql.com/doc/refman/5.6/en/replication.html   MySQL Forums: Replication http://forums.mysql.com/list.php?26

Documents

MySQL Replication HOL v2Title MySQL Replication HOL v2.ppt Author Wei-Chen Chiu Created Date 3/6/2013 6:38:10 AM