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