manager for multiple PostgreSQL client versions The postgresql-client-common package provides a structure under which multiple versions of PostgreSQL client programs may be installed at the same time. It provides a wrapper which selects the right version for the particular cluster you want to access (with a command line option, an environment variable, /etc/postgresql-common/user_clusters, or ~/.postgresqlrc). 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.