pgpool is a connection pool server for PostgreSQL. pgpool runs between PostgreSQL's clients (front ends) and servers (back ends). A PostgreSQL client can connect to pgpool as if it were a standard PostgreSQL server. pgpool caches the connection to a PostgreSQL server to reduce the overhead to establish the connection to it. Also, pgpool can use two PostgreSQL servers for fail over. If the first server goes down, pgpool will automatically switch to the secondary server. Moreover, pgpool supports scheduled switch over.
Release Notes: HBA authentication is supported. log_connections and log_hostname are supported. pgpool status is shown in the ps command. A bug with prepared queries was fixed. The secondary server is detached when "kind mismatch error" is detected. A socket is reopened if it was closed by a backend while reusing a connection.