The postgresql-common package provides a structure under which
 multiple versions of PostgreSQL may be installed and/or multiple
 clusters maintained at one time.
 .
 The commands provided are pg_conftool, pg_createcluster, pg_ctlcluster,
 pg_dropcluster, pg_lsclusters, pg_renamecluster, pg_upgradecluster,
 pg_virtualenv.
 .
 PostgreSQL is a fully featured object-relational database management
 system. It supports a large part of the SQL standard and is designed
 to be extensible by users in many aspects. Its features include ACID
 transactions, foreign keys, views, sequences, subqueries, triggers,
 outer joins, multiversion concurrency control, and user-defined types
 and functions.