PostgreSQL for Oracle Developers and DBA's

Command Prompt, Inc.http://www.commandprompt.com/

@cmdpromptinc

Postgres for Oracle people

http://www.commandprompt.com/


@cmdpromptinc

Professional Services

For professional services or support contracts for all of your Oracle to PostgreSQL or Open Source needs, please contact CMD at:

● +1.503.667.4564● [email protected]● https://www.commandprompt.com/


mailto:[email protected]


@cmdpromptinc

Who Am I

● @jdatcmd/@linuxhiker

● [email protected]

● Lead Architect – Command Prompt, Inc.

● Director & Founder – PgUS (501c3)


mailto:[email protected]


@cmdpromptinc

Why PostgreSQL

● Licensing● Community● Business● Tech!



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Licensing

● BSD licensed● Can I?



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Can I?

● Fork it?: Yes● Close it?: Yes● Modify it?: Yes● Not share it?: Yes● Throw it away?: Yes● Sue you?: Nein!



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Community

● Large International Community:– Postgresql.org

● Postgresql.us● Postgresql.eu

– Germany, Nordic, France, Italy...● Postgresql.jp● Postgres.cn



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Business

● Costs● Support



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Costs

● PostgreSQL is 100% free.– Zero cost to download

– Zero cost to install

– Zero cost to support (assuming expertise)



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Established companies(Support)

● Command Prompt, Inc (oldest, yes that’s us)● Crunchy● Credativ● OmniTI● OpenSCG● 2ndQuadrant

(list goes on and on)



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EnterpriseDB?

● They specialize in a closed source fork not Open Source PostgreSQL



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Tech

● The basics● Features● Quirks



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The basics

● ACID Compliant

● Rich datatypes

– Standards such as varchar(), integer, numeric etc..

– XML, JSON/B, Money, Hstore...

● Rich builtin functions

– to_char(),to_date(),overlaps(),enum_first(),xpath(),greatest(),in(),any(),some(),trim,overlay()...

● Constraints

– CHECK, PRIMARY KEY, NOT NULL…

● Referential Integrity

– Foreign Keys (Deferrable, Initially Deferred)

● Partitioning

● SCHEMA (namespaces)



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Features

● Solid SQL implementation● Mature code base● “Enterprise”● Cool stuff’● Of note



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Solid SQL Implementation

No current version of any database management system claims full conformance to Core SQL:2011.

PostgreSQL supports most of the major features of SQL:2011. Out of 179 mandatory features required for full Core conformance, PostgreSQL conforms to at least 160. In addition, there is a long list of supported optional features.



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ISO/IEC SQL Implementation

● ISO/IEC 9075-1 (SQL/Framework)

● ISO/IEC 9075-2 (SQL/Foundation)

● ISO/IEC 9075-9 (SQL/MED)

– FDW, DBI-LINK

● ISO/IEC 9075-11 (SQL/Schemata)

● ISO/IEC 9075-14 (SQL/XML)

– Native XML handling and functions● ISO/IEC 9075-13 (SQL/JRT(Java))

– PL/JAVA



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Mature code base

PostgreSQL started as Ingres at the University of California, Berkeley in the 1970s.

Current iterations have been in continual development since 1997.



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Enterprise features

● It’s Free! No licensing audits.● FDW● Backup and recovery● Replication● Table spaces● Transactional DDL● UDF

– We don’t have packages



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It’s free. No licensing audits

● Oracle has spawned an entire industry to defend against the possibility of an audit.

● PostgreSQL has spawned an entire industry letting businesses and developers use a database.



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FDW

Foreign Data Wrappers

Connect to external data sources including Oracle! (CREATE DATABASE LINK)



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Backups and Recovery

● Online logical backups (pg_dump/pg_dumpall)● Online binary backups (pg_basebackup,

pgBackrest, (tar,cpio,cp,rsync))● Point In Time Recovery (PITR)



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Replication

● Logical Replication (pgLogical, Slony, Londiste)● Binary Replication (Warm,Cold and Hot

Standby). SYNC AND ASYNC● Load balancing

– Pgpool-II->Master->(n)Slaves



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Table Spaces

Postmaster

Warehouse TBLSpace

Transactional TBLSpace

Indexes



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Transactional DDL

BEGIN;

CREATE TABLE foo (

id BIGSERIAL PRIMARY KEY,

fname TEXT NOT NULL

CHECK(fname ~ ‘[^[:alnum:]_]’)

);

COMMIT/ROLLBACK;

BEGIN;

ALTER TABLE foo ADD COLUMN lname TEXT NOT NULL;

SELECT test_foo_column_laname();

COMMIT/ROLLBACK;



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UDF

● Can be written in a number of languages– C

– SQL

– PL/PgSQL (similar to PL/SQL)

– Python

– Ruby

– Perl

– V8 (JavaScript)

– Java

– Lots more



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Cool stuff

● Savepoints● Two Phase Commit

– XA

● SELinux integration● Column, Row permissions (versus just relation)● Extensions● GIS/Postgis



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Savepoints

● Similar to Oracle:

BEGIN;

INSERT INTO table1 VALUES (1);

SAVEPOINT my_savepoint;


ROLLBACK TO SAVEPOINT my_savepoint;


COMMIT;



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Two Phase Commit

● Intended use by external transaction managers– XA implementation via JDBC driver

● Can be used via SQL● Review: max_prepared_transactions

configuration parameter● Always clean up, will interfere with maintenance



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selinux

● For more information visit:https://wiki.postgresql.org/wiki/SEPostgreSQL_SELinux_Overview



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Column/Row Permissions

● Column level privs are set using standard GRANT/REVOKE

● ROW level privs are set via a policy method:https://www.postgresql.org/docs/9.5/static/ddl-rowsecurity.html



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Extensions

● Column Database (Citus)● Auditing (PgAudit)● Case insensitive index search (Citext)● And more (pgxn.org)



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Of note● Use TEXT for CLOB, BYTEA (or lo) for BLOB● NULL is different:

postgres=# create table bar(a text);CREATE TABLEpostgres=# insert into bar values('');postgres=# select * from bar where a IS NULL; a ---(0 rows)postgres=# insert into bar values(NULL);postgres=# select * from bar where a IS NULL; a --- (1 row)

● PostgreSQL has a boolean data type.



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GIS/PostGIS

● Full Geometric support including– Datatypes

– Functions

● Extended support through PostGIS (external project).



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Of note (2)

● No connect by– Use “WITH RECURSIVE”

● PostgreSQL is much more reliant on the host operating system than Oracle. Make sure you are running an LTS, UNIX (Solaris) or FreeBSD.



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Tools for easing migration

● Ora2pg– Complete migration toolkit

● Orafce– Implements compatibility layers that are 10g

compatible including but not limited to:● Oracle date functions● Oracle.date data type● Oracle data operators etc...



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What we don’t have

● No RAC● No Packages● No Flashback (on main system, can be

achieved via PITR/Cold standby)



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Questions?

● Business● Community● Technical


PostgreSQL for Oracle Developers and DBA's

Technology

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