PostgreSQL Essential Reference

Implemented FOREIGN KEYS (except PARTIAL MATCH FKs ).

Major overhaul to query optimizer.

Psql client application added many new features.

Date-time data types now SQL-92 “compliant.

Removed fixed-length limit of query strings.

Maximum number of keys in an index increased to 16 from 8.

Sorts and hashes fixed to work on greater than 2GB of data.