PostgreSQL

PostgreSQL is a relational database system that belongs in the class of open-source software that stands out for its robustness, scalability, and accomplishment of SQL standards.

There are versions available for a wide range of operating systems, including Linux, Windows, Mac OS X, Solaris, BSD, Tru64, and others.

PostgreSQL supports ACID, in other words completing secure transactions, as well as supporting views, joins, foreign keys, stored procedures, triggers, etc.

It includes the majority of data types specified in standard SQL92 and SQL99, like INTEGER, NUMERIC, BOOLEAN, CHAR, VARCHAR, DATE, INTERVAL, and TIMESTAMP.

Other interesting features included in PostgreSQL include:

-High concurrency, which avoids having to block a table when you're working in it

-Online/hot backups

-Asynchronous replication

-Nested transactions

-Query optimization

If it's data that interests you, then you should know that there is no maximum size of a database in PostgreSQL; that the size of a table can be up to 32 TB, a row 1.6 TB, and a field 1 GB. The number of rows in a table is unlimited, but not columns, which have a max be between 250 and 1600 per table. The maximum indexes per table is also unlimited.