Before you can do anything, you must initialize a database storage area on disk. We call this a database cluster. (SQL uses the term catalog cluster.) A database cluster is a collection of databases that is managed by a single instance of a running database server. After initialization, a database cluster will contain a database named postgres, which is meant as a default database for use by utilities, users and third party applications. The database server itself does not require the postgres database to exist, but many external utility programs assume it exists.
open-source Object-Relational DBMS
Creating the Backup
The idea behind the SQL-dump method is to generate a text file with SQL commands that, when fed back to the server, will recreate the database in the same state as it was at the time of the dump. PostgreSQL provides the utility program pg_dump for this purpose. The basic usage of this command is:
- Ora2pg -a Perl module to export an Oracle database schema to a PostgreSQL compatible schema
- Orafce -implemente some functions from Oracle database next_day, last_day, trunc, round, DBMS_ALERT, DBMS_OUTPUT, UTL_FILE, DBMS_PIPE, ...
- PL/pgSQL -PL/pgSQL is a loadable, procedural language, similar to the Oracle procedural language, PL/SQL.
- PL/Java - brings JavaTM Stored Procedures, Triggers, and Functions to the PostgreSQL