First, we'll harness Tungsten Replicator's flexibility to implement heterogeneous replication from MySQL to PostgreSQL. Then, we'll introduce advanced logical replication for PostgreSQL, which opens up new horizons in replication abilities. Finally, we'll take a look at how logical replication enables data replication from PostgreSQL to MySQL.

1. Linas Virbalas
Continuent, Inc.
© Continuent 2010

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

4. Heterogeneous Replication

Replication between different types of DBMS
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5. 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
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6. / 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

7. © Continuent 2010

8. 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
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9. With Tungsten Replicator
Why?
Because It Can! :)
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10. / Interfaces to implement new:
• Extractors
• Filters
• Appliers
/ Multiple replication services per one process
/ JAVA
/ Open Source GPL v2
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11. Technology: Replication Pipelines
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13. / Statement Based Replication
/ Row Based Replication
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15. Tungsten Tungsten
Replicator Replicator
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16. Master Slave
Replicator Replicator
Transaction Transaction
History Log History Log
Filters Filters
MySQL PostgreSQL
Extractor Applier
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17. / 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
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18. Provisioning
/ Harder way: Dump data explicitly
/ Easier way: Replicate a mysqldump backup
Replicator
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19. / 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
…
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20. 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
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21. / 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”;
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22. / 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);
…
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23. / 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);
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26. 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
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27. 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
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28. Master Slave
Replicator Replicator
Transaction Transaction
History Log History Log
Filters Filters
PostgreSQL
SlonyExtractor

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31. Master Slave
Replicator Replicator
Transaction Transaction
History Log History Log
Filters Filters
PostgreSQL MySQLApplier
SlonyExtractor

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35. 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