PL/Proxy is a PostgreSQL procedural language (PL) handler that allows to do remote procedure calls between PostgreSQL databases, with optional sharding.

Language has four statements:

• Pick remote database:
  • CLUSTER <name> - use pre-configured cluster that has many databases
  • CONNECT <connstr> - use connstr directly
• Set execution type:
  • RUN ON ALL - query is run on all databases in parallel
  • RUN ON ANY - pick server randomly
  • RUN ON <hash> - map hash to database
• Replace default query:
  • SELECT ...

Example:

CREATE FUNCTION get_user_settings(i_username text) RETURNS SETOF user_settings AS $$
    RUN ON namehash(i_username):
$$ LANGUAGE plproxy;

It will run function with same name in remote database and fetch user_settings record.

For installation there must be PostgreSQL dev environment installed and pg_config in the PATH. Then just run:

$ make
$ make install

To run regression tests:

$ make installcheck

Location to pg_config can be set via PG_CONFIG variable:

$ make PG_CONFIG=/path/to/pg_config
$ make install PG_CONFIG=/path/to/pg_config
$ make installcheck PG_CONFIG=/path/to/pg_config

Note: Encoding regression test fails if the Postgres instance is not created with C locale. It can be considered expected failure then.