This document discusses migrating from legacy databases to MariaDB. It begins with an agenda that covers why migrate to open source, what to migrate and what not to migrate, MariaDB server compatibility features from versions 10.1 to 10.3, and MariaDB migration services and case studies. It then discusses reasons to migrate to open source like lower costs and more modern infrastructure. It provides examples of what types of applications and code are easier or harder to migrate. It also covers MariaDB compatibility features and an example schema and procedure migration. Finally, it discusses MariaDB migration services and provides summaries of two case studies migrating from Oracle to MariaDB.

1. From Legacy to Open
Source
Migrating from legacy
databases to MariaDB

2. Agenda
• Why migrate to Open Source
• What to migrate and what not to migrate
• MariaDB Server compatibility features
– MariaDB Server up to version 10.1
– MariaDB Server 10.2
– MariaDB Server 10.3
• MariaDB Migration services
• Case Studies
• Questions and Answers

3. Why migrate to Open Source
Total Cost of Ownership
High Performance
High Availability

4. Why Open Source?
• Modern, inexpensive and powerful hardware
– Commodity hardware
• Agile software development
– More software
– High quality software
– At lower cost
• Modern infrastructure is more and more based on Open Source
– Cloud technologies
– Containers
– Microservices
– DevOps development

5. Why Open Source?
• You just cannot avoid Open Source software
• Higher security
– More eyeballs looking at software
– Ability to0 verify claims of security
• Easier software licensing
– Legacy software licenses are complex
– A big part of Vendor lock-in is due to licensing
• Significantly lower Total Cost of Ownership (TCO)

6. What and what not to
Migrate
Finding the low hanging
fruit

7. Types of migration targets
• Impossible to migrate
– Means that a complete rewrite takes less effort than a migration
– May also be the case that it is not worthwhile, for example the code base is too old
• Complex migration
– Lots of proprietary code
– Use of proprietary features in key areas
– Complex application
– Lack of or bad documentation
• Medium complexity
– Limited amounts of proprietary code
– Well documented code
– Using Standard features

8. Types of migration targets
• Easy migration
– Using only standard features
– Separate database layer
• Standard or custom
– Standard database data types
– Small amounts of highly complex SQL
– Well documented application and code
– Standard development languages

9. What to look out for
• Database procedural code, i.e. PL/SQL
– Not necessarily a big issue but needs to be investigated
– Migration is possible
• Complex SQL statements
– Tuning issues
– Proprietary features
• Dynamic SQL
– Difficult to migrate
– Difficult to tune
– Difficult to test

10. What to look out for
• Non standard data types
– BLOB/CLOB types are sometimes difficult, implementations are different
– Temporal datatypes are also notoriously difficult due to semantic differences
– Numeric datatypes are sometimes an issue
– User Defined Datatypes
• Characters sets and collations
– UTF-8 support
• Non-standard table types
– Special indexes
– Materialized Views
– Nested tables

11. MariaDB Server Compitability
Easing migrations

12. Compatibility in MariaDB Server pre 10.2
• SQL_MODE = Oracle
– Pipes as CONCAT - || treated as MariaDB CONCAT function
– Quoting for names according to ANSI – " treated as MariaDB `
• CHECK Constraints
– Accepted syntax only
• SQL_MODE retained for Stored Procedures and Functions
• Mainly ANSI SQL datatypes
• User Defined Functions and Stored Routines to augment migration
• Convert PL/SQL to external code and/or SQL/PSM
• Partitioning
• ANSI SQL Outer Join syntax
– Oracle, Sybase and SQL Server outer join syntax replacement

13. Compatibility in MariaDB Server 10.2
• CHECK Constraints
– Implemented and operational in accordance with ANSI SQL
• CTE – Common Table Expressions
– Eases use of temporary objects
– Replacement for Oracle CONNECT BY … PRIOR syntax
• Windowing functions
– In line with Oracle support
• Column DEFAULT expressions enhanced
– In line with ANSI SQL and Oracle
• User based resource limitations
• Enhanced PREPARE statement
• Multiple TRIGGERs per event

14. Compatibility in MariaDB Server 10.3
• PL/SQL support
– Most of the PL/SQL syntax supported
– PACKAGES support
– Minimal set of built-in packages support
• SEQUENCES support
• Support for parameterized CURSORs
• Several Oracle compatibility functions
• INTERSECT and EXCEPT support
• ROW data types in Stored Procedures
• System Versioned Tables / AS OF – To replace Oracle Flashback

15. Example schema migration
#: let's create some tables, using ORACLE DATA TYPES
MariaDB [mydb]> CREATE TABLE TBL_CAR_BRAND (
-> CAR_BRAND_NUMBER INTEGER(10) NOT NULL,
-> CAR_BRAND_DESC VARCHAR2(4000) NOT NULL, #: mapped out to MariaDB VARCHAR
-> CAR_BRAND_LOGO BLOB, #: mapped out to MariaDB LONGBLOB
-> PRIMARY KEY(CAR_BRAND_NUMBER)
-> ) ENGINE=InnoDB;
Query OK, 0 rows affected (0.007 sec)
MariaDB [mydb]> CREATE TABLE TBL_CAR (
-> CAR_NUMBER INTEGER(10) NOT NULL,
-> CAR_BRAND_NUMBER INTEGER(10) NOT NULL,
-> CAR_MODEL VARCHAR2(60) NOT NULL,
-> CAR_MODEL_PRICE NUMBER(10,2) NOT NULL, #: mapped out to MariaDB DECIMAL
-> CONSTRAINT FOREIGN KEY (CAR_BRAND_NUMBER) REFERENCES TBL_CAR_BRAND(CAR_BRAND_NUMBER),
-> PRIMARY KEY(CAR_NUMBER)
-> ) ENGINE=InnoDB;
Query OK, 0 rows affected (0.007 sec)

16. Example procedure migration
MariaDB [mydb]> DELIMITER /
MariaDB [mydb]> CREATE OR REPLACE PROCEDURE mydb.PROC_ADD_CAR_BRAND (
p_car_brand_descmydb.TBL_CAR_BRAND.CAR_BRAND_DESC%TYPE,
p_car_brand_logomydb.TBL_CAR_BRAND.CAR_BRAND_LOGO%TYPE
) AS
BEGIN
IF ((p_car_brand_desc <> '') &&(p_car_brand_logo <> '')) THEN
-- creating a start savepoint
SAVEPOINT startpoint; #: creating an undo point into the local stream
-- inserting the new row
INSERT INTO TBL_CAR_BRAND(CAR_BRAND_NUMBER,CAR_BRAND_DESC,CAR_BRAND_LOGO)
VALUES(SEQ_CAR_BRAND.NEXTVAL,p_car_brand_desc,p_car_brand_logo);
ELSE
SELECT 'You must provide the cars brand...' AS WARNING;
END IF;
EXCEPTION
WHEN OTHERS THEN
-- executing the exception
SELECT 'Exception ' || TO_CHAR(SQLCODE)|| ' ' || SQLERRM AS EXCEPTION;
-- rolling backup to the savepoint startpoint
ROLLBACK TO startpoint;
END;
/
Query OK, 0 rows affected (0.003 sec)

17. MariaDB Migration Services

18. MariaDB Migration Practice services
• Competence in MariaDB, MySQL, Oracle, SQL Server and several other database systems
• Migration assessment
– Assess if a migration is feasible
– Determine application complexity
– Determine an approximate effort for migration
• Migration Proof-of-concept
– Migrate distinct part of an application
– Use to ensure that a migration is feasible, possible and useful
– Uncover hidden complexities
– Covers database and well as select application and infrastructure components

19. MariaDB Migration Practice tasks
• Schema migration
• Data migration
• Data validation
• Database Procedural code migration
– Including Procedural code validation
• Application migration
– MariaDB Migration Practice focus on the database specific aspects of the application
• Application testing and tuning
• Switchover

20. MariaDB Migration process

21. Case studies
Background and
examples

22. Greetz – Oracle RAC to MariaDB Galera Cluster
• Application – E-commerce for Personalized Greeting Cards
• Business Challenges
– High Availability
– Cost
– Predictable performance
• Solution
– Migrate from Oracle RAC to MariaDB Galera Cluster
• Why MariaDB
– Lower Total Cost of Ownership
– Lower hardware cost
– Lower DBA requirements
“MariaDB’s controlled and structured
approach gave us certainty in relation
to data and enabled us to go live on
time. I would not hesitate in working
again with SkySQL and highly
recommend them.“
— Giulio Gaioni, COO, Greetz

23. Greetz Migration – Some details
• Java application
– Using Hibernate for database access
• Application code required minimal effort
– Certain hardcoded Hibernate objects required changing
• Small amounts of PL/SQL code
– Mostly used for reporting and DBA work
– Replaced with Linux shell scripts and limited amount of MariaDB SQL/PSM code
• Oracle RAC replaced by MariaDB Galera Cluster
• Hardware was leased
– Shared disk system could be returned immediately after migration
– Significant part of migration cost saving
• MariaDB Remote DBA to aid in database work

24. DBS Bank – Migration from Oracle to MariaDB
• DBS Bank Singapore
– The biggest banks in Southeast Asia.
– 27 applications have already been successfully migrated to MariaDB by 2017
• Including some of the most complex ones
– Several more application in pipeline for 2018
• Heavy-duty transactional data mart for OLTP applications
– Data is then provided to customer-facing applications
– 16 countries, 250 tables, 130 procedures, 4 TB hot data, 15 TB cold data
• Main drivers
– Cost
– Drive towards Open Source

25. DBS Bank migration – Some challenges
• Proof of Concepts
– Many potential issues found during PoC
• Density of internal application knowledge
– Live application which has been growing over years → hundreds of procedures etc.
• Dependency on Oracle features
– CONNECT BY, PIPE ROW, non-1NF custom types
– Feature development for frequently used constructs
– Solution/workaround development for less frequently used constructs, e.g. collections
• Complexity due to long-term growing architecture
– Tight couplings and dependencies with neighboring systems
– Direct access to tables from/to other applications, i.e. bypassing application calls

26. Thank you