for PostgreSQL is now in RC1:
pgpool is a single master/query based/synchronous replication
server. It acts as a proxy server between PostgreSQL client and
PostgreSQL server. No application change is needed to use pgpool.
pgpool's features include:
o connection pooling. This will reduce the connection establishing
o pre-forking child processes. Like Apache, pgpool pre-forks child
processes to provide faster service startup.
o degeneration. In the replication mode, if one of PostgreSQL goes
down, it detaches the broken server and continues operation with the
o fail over. In the connection pool server mode, if master PostgreSQL
goes down, it detaches the broken server and continues operation
with the stand-by server.
In addtion to above, 2.0 supports native V3 protocol which should make
pgpool faster if used with PostgreSQL 7.4 or later.
Also, now pgpool supports the load balancing between master/secondary
PostgreSQL backends to gain better performace for SELECT statement.