Flexible Replication

Linas Virbalas Continuent, Inc.© Continuent 2010

/  Definition & Motivation /  Three Stories /  How? /  Questions and Answers© Continuent 2010

Heterogeneous Replication  Replication between different types of DBMS© Continuent 2010

1.  Real-time integration of data between different DBMS types 2.  Seamless migration out of one DBMS type to another 3.  Data warehousing (real-time) from different DBMS types© Continuent 2010

/  Name: Linas Virbalas /  Country: Lithuania /  Implementing for Tungsten: •  MySQL -> PostgreSQL •  MySQL -> Greenplum •  MySQL -> Oracle •  PostgreSQL WAL •  PostgreSQL Streaming Replication •  PostgreSQL Logical Replication via Slony logs /  Blog: http://flyingclusters.blogspot.com© Continuent 2010

1.  Story of MySQL -> … •  How to replicate from MySQL to PostgreSQL/Greenplum? Oracle? 2.  Story of PostgreSQL -> PostgreSQL •  Advanced Logical Replication 3.  Story of PostgreSQL -> … •  For now: how to replicate from PostgreSQL to MySQL© Continuent 2010

With Tungsten Replicator Why? Because It Can! :)© Continuent 2010

/  Interfaces to implement new: •  Extractors •  Filters •  Appliers /  Multiple replication services per one process /  JAVA /  Open Source GPL v2© Continuent 2010

Technology: Replication Pipelines© Continuent 2010

/  Statement Based Replication /  Row Based Replication© Continuent 2010

Tungsten Tungsten Replicator Replicator© Continuent 2010

Master Slave Replicator Replicator Transaction Transaction History Log History Log Filters Filters MySQL PostgreSQL Extractor Applier© Continuent 2010

/  Provisioning /  Data Type Differences /  Database vs. Schema /  Default (Implicitly Defined) Schema Selection /  SQL Dialect Differences •  Statement Replication vs. Row Replication /  Character Sets and Binary Data /  Old Versions of MySQL© Continuent 2010

Provisioning /  Harder way: Dump data explicitly /  Easier way: Replicate a mysqldump backup Replicator© Continuent 2010

/  Note the type differences between MySQL and PG MySQL PostgreSQL ! TINYINT SMALLINT SMALLINT SMALLINT INTEGER INTEGER BIGINT BIGINT ! CHAR(1) CHAR(5) = {‘true’, ‘false’} CHAR(x) CHAR(x) VARCHAR(x) VARCHAR(x) DATE DATE TIMESTAMP TIMESTAMP ! TEXT (diff. sizes) TEXT ! BLOB BYTEA …© Continuent 2010

Database vs. Schema /  In MySQL these are the same: ! !CREATE DATABASE foo! ! !CREATE SCHEMA foo! /  In PostgreSQL these are very different: CREATE DATABASE foo! ! !CREATE SCHEMA foo! /  Tungsten uses filters to rectify MySQL databases to PostgreSQL schemas© Continuent 2010

/  MySQL: Trivial to use `USE` /  MySQL: Going without `USE` generates different events MySQL Implicit MySQL Explicit CREATE SCHEMA s; CREATE SCHEMA s; USE s; ! CREATE TABLE t (i int); CREATE TABLE s.t (i int); ! INSERT INTO t (1); INSERT INTO s.t (1); /  PG: Extract the default schema from the event /  PG: Set it before applying MySQL PostgreSQL USE s; > SET search_path TO s, "$user”;© Continuent 2010

/  Differences between DDL and DML statement SQL dialects /  Row Replication resolves issues rising from differences in DML, but still leaves DDL to handle /  Tungsten Replicator Filters come to the rescue! •  Simple to develop Java or JavaScript extensions •  Event structure IN -> Filter -> Event structure OUT MySQL PostgreSQL CREATE TABLE complex (id CREATE TABLE complex (id INTEGER AUTO_INCREMENT SERIAL PRIMARY KEY, i INT); PRIMARY KEY, i INT); CREATE TABLE dt (i TINYINT); CREATE TABLE dt (i SMALLINT); …© Continuent 2010

/  Statement replication: MySQL syntax is “permissive” /  Embedded binary / alternate charsets /  Different charsets for different clients /  Row replication: database/table/column charsets may differ /  Answer: Stick with one character set throughout; use row replication to move binary data MySQL PostgreSQL INSERT INTO embedded_blob ARGH!!! (SQL statement fails) (key, data) VALUES (1, ‘?0^Es 0^0’’) create table xlate(id int, d1 ARGH!!! (no way to translate to varchar(25) character set common charset) latin1, d2 varchar(25) character set utf8);© Continuent 2010

Logical Physical MySQL Statement Based x MySQL Row Based x MySQL Mixed x PostgreSQL WAL Shipping x PostgreSQL Streaming Replication x Filters (data transformation) possible + - Different data/structure on slave + - possible /  A transaction is not accessible to the replicator under physical replication /  Tungsten Replicator manages WAL/Streaming Replication© Continuent 2010

Logical Physical MySQL Statement Based x MySQL Row Based x MySQL Mixed x PostgreSQL WAL Shipping x PostgreSQL Streaming Replication x Tungsten Replicator w/ x PostgreSQLSlonyExtractor Filters (data transformation) possible + - Different data/structure on slave + - possible /  With PostgreSQLSlonyExtractor transaction goes through the Replicator pipeline© Continuent 2010

Master Slave Replicator Replicator Transaction Transaction History Log History Log Filters Filters PostgreSQLSlonyExtractor

Master Slave Replicator Replicator Transaction Transaction History Log History Log Filters Filters PostgreSQL MySQLApplierSlonyExtractor

Open Source Commercial http://tungsten-replicator.org sales@continuent.com #tungsten @ irc.freenode.net My Blog: http://flyingclusters.blogspot.com Continuent Web Site: http://www.continuent.com© Continuent 2010

Flexible Replication

by Linas Virbalas on May 23, 2011

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Flexible Replication — Presentation Transcript