Higher impact of license costs
Agile Oracle to PostgreSQL migrations
PGConf.EU 2013, Dublin, Nov 1st
Gabriele Bartolini
2ndQuadrant Italia / PostgreSQL [email protected]
@_GBartolini_
Gabriele Bartolini•Co-Founder and Manager of 2ndQuadrant Italia
• Data Architect, Business critical environments
• Data warehousing
•Co-Founder Italian PostgreSQL Users Group
•Co-Founder PostgreSQL Europe
•PostgreSQL Contributor and Advocate
Outline• Introduction
•The migration project
•Open source tools
•Conclusions
Target•Chief Technical Officers
•Chief Information Officers
•Oracle users
• Evaluate moving to PostgreSQL 9.3
Goals•Describe the migration process
•Spot the major sources of costs
•Help you plan a migration in the mid/long term
Part IIntroduction
Oracle vs Postgres
(*) not sure it is in the TODO List, yet
Upgrade automaticallyWould you ever do an upgrade to a higher version of
Oracle in a completely automated way?
PostgreSQL•Hot Standby (~ Data Guard)
•Barman (~ RMAN)
•Londiste/PgQ (GoldenGate)
•PostGIS (Spatial)
•SE Linux integration (~ Database Vault)
•Memcache integration (~ In-Memory Database Cache)
•Partitioning (*)
•Future: Multi-master replication (~ RAC)
License•Very simple and clear
•Applies to every part (module, product, option) of Postgres
• server, client, libraries, additional modules
• 100% open source
•No need to hire a lawyer to understand it
•Highly Permissive
• Not subject to monopoly nor acquisitions
•Fosters market competition in professional services offer
Oracle DBA, do not be afraid!•Transferrable knowledge
•PostgreSQL focused professional training
•100% open source
Part IIThe Migration project
Migration = projectbudget, scope, quality, time
Budget•Crucial variable
• Usually triggers the migration process
•Cost analysis drives the migration project
• short term
• mid term
Quality•PostgreSQL reliability
•Tests
Components•Applications
•Database
•Processes
•Human resources
Migration cost components
25,00% 50,00%
Dev Testing Processes Training Licensing
fictit
ious
dat
a
Comparison with Oracle upgrade
25,00% 50,00%
Dev Testing Processes Training Licensing
fictit
ious
dat
a
External applications•Force your supplier to provide Postgres support for their
application
• You set the rules
•Typical case of the public sector
• e.g.: Land registry
• Financial crisis and competition are on your side
Agile approach• Requirements change
• Every context is different from the other
• No one-size-fits-all scenario
• Be dynamic:
• SCRUM (with the customer)
• Kanban (internally)
• DevOps
Focus•Applications
•Database
•Processes
•Human resources
Database migration•Schema
•Queries
•Data
•Stored procedures
•Tests
Schema conversion•Tables
• Data type mapping
• Indexes
•Views
•Constraints
Schema major differences•USER = schema/database
•UPPERCASE = lowercase
•Partitioning (*)
•Tablespaces
•SYNONYMs
• search_path / auto updatable views / foreign tables
Queries•ANSI/ISO SQL
•PostgreSQL has no hints (optimiser)
•Major differences:
• NULL = NULL
• Postgres: NULL
• Oracle: TRUE
• OUTER JOINs
• (+)
• use LEFT/RIGHT JOIN
• DUAL
• ROWNUM and ROWID
• ...
Data•Might require specialised
consulting activities
•Major solutions:
• ETL tools (e.g. Kettle)
• External scripts (e.g. ora2pg or custom)
• COPY t FROM stdin;
• Foreign tables with Oracle FDW
• INSERT INTO t SELECT * FROM ft;
• Cut-over time
• > 0
• ~ 0
Stored Procedures•Most critical and complex component of the whole migration
•Package = extension (schema)
•Two major ways:
• 1:1 conversion (not always possible)
• complete rewriting (optimised for PostgreSQL)
• It might required specialised consulting activities
PL/SQL vs PL/pgSQL•Syntactical differences
•PROCEDURE = FUNCTION that returns VOID
•TRIGGER = TRIGGER FUNCTION + TRIGGER
•Lack of autonomous transactions
•Lack of global variables
• ...
Test•Vital component for a successful migration process
• It measures the QUALITY of the project
• It can be reused in the future for PostgreSQL upgrades
• strategic investment in the long period
Part IIIOpen source tools
ora2pg•URL: http://ora2pg.darold.net/
•Written in Perl - GNU GPL 3
•Reads the information schema from Oracle
•Generates DDL instructions for PostgreSQL
•Highly configurable (mapping data type conversions)
•Basic support for PL/SQL (regexp)
orafce•URL: http://orafce.projects.pgfoundry.org/
•C and SQL - BSD licensed
•Set of functions, objects and modules that are part of Oracle:
• NVL function (COALESCE)
• DBMS_ALERT, DBMS_OUTPUT, UTL_FILE, ...
• DUAL
Oracle FDW•URL: http://oracle-fdw.projects.pgfoundry.org/
•SQL/MED
• uses the API for Foreign Data Wrapper
• CREATE FOREIGN TABLE
• Currently READ ONLY
•Useful for ETL
Example of Oracle FDW...CREATE FOREIGN TABLE oracle_table ( id integer NOT NULL, ...) SERVER oradb OPTIONS (schema 'ORAUSER', table 'ORATAB');...-- pushes down the WHERE clauseSELECT * FROM oracle_table WHERE id=10;
PgTap•Unit tests suite for PostgreSQL
•Extensions (functions)
•Produces TAP output
•Test Driven Development in databases
Vagrant•Open Source software
•Creation and configuration of virtual environments
•Provisioning: Puppet, Chef
•Useful for local testing
PostgreSQL•Every major release of Postgres reduces the technology gap
with Oracle
•5 years ago, Postgres did not have hot standby, streaming/synchronous/cascading replication, window functions, CTEs, column permissions, foreign tables, serialisable isolation level, XML, JSON, updatable and materialised views ...
• Is it called “OraGIS” or “PostGIS”?
•Postgres does have transactional DDL
Master Standby
App
Business Continuity stack
DR
server C
repmgr
Barmanserver A server B
If you really miss it ...CREATE USER scott WITH PASSWORD ‘tiger’;CREATE DATABASE scott WITH OWNER scott;\c scott scottCREATE SCHEMA scott;
Part IVConclusions
0
30.000
60.000
90.000
120.000
150.000
180.000
210.000
240.000
270.000
300.000
Costs in Euro
35.000
70.000
140.000
16.000
32.000
64.000
7.5001 CPU Socket 2 CPU Socket 4 CPU Socket PostgreSQL*
License Support
Cost analysis of a database solution on a period of 3 years for 1 server
* PostgreSQL with 24/7 support from us
015.00030.00045.00060.00075.00090.000
105.000120.000135.000150.000
Costs in euro70.000
16.000 16.000
50.000
2.500 2.500
Anno 1 Anno 2 Anno 3
Oracle PostgreSQL
Cost analysis of a migration to PostgreSQL in a 3 year period
* PostgreSQL with 24/7 support from us
Conclusions•Final solution: 100% open
source
• reduced TCO
• No vendor lock-in
•Migration must be focused on costs evaluation
•Supervised process (not automated)
• If a feature is missing, you can simply sponsor it
• If needed, professional companies can help you before, during and after the migration process (you won’t be alone)
Thank you!Licenza Creative Commons BY-NC-SA 3.0
http://creativecommons.org/licenses/by-nc-sa/3.0/it/deed.it
