This code is almost entirely from Peter Eisentraut peter@eisentraut.org and his project https://github.com/petere/plsh.git PL/sh.. I've just changed the name from 'plsh' to 'plsix', and I want to change it to properly do execve(2) in order to run '/usr/bin/env perl6'. I've been playing with this for most of the development cycle.
PL/six is a procedural language handler for PostgreSQL that allows you to write stored procedures in Perl 6 - this is heavily derived from pl/sh.
A sample stored function looks like:
CREATE FUNCTION query (x int) RETURNS text
LANGUAGE plsix
AS $$
#!/path/to/your/perl6
my $x = @ARGS[0];
say "argument is $x";
$$;
You'll need to open your own DB connection if you want to do anything, please see DBIish for that side.
The body of the function will get copied into a /tmp/plsix-XXXXX file and evaluated by perl6. This should be "#!/usr/bin/env perl6" but I haven't quite cracked that yet. Arguments are passed in the @ARGS array, so you may want to play with sub MAIN at some point. Output goes from STDOUT directly back to Postgres. To return NULL, don't print anything. To throw an error, warn() or die() as appropriate, or exit with a non-zero status.
Triggers should run, but won't alter rows because the interface doesn't parse the output back into SQL.
The distribution also contains a test suite in the directory test/
,
which contains a simplistic demonstration of the functionality.
Peter Eisentraut peter@eisentraut.org
You can't access the database directly from PL/sh through something
like SPI, but PL/sh sets up libpq environment variables so that you
can easily call psql
back into the same database, for example
CREATE FUNCTION query (x int) RETURNS text
LANGUAGE plsh
AS $$
#!/bin/sh
psql -At -c "select b from pbar where a = $1"
$$;
Note: The "bin" directory is prepended to the path, but only if the PATH
environment variable is already set.
In a trigger procedure, trigger data is available to the script through environment variables (analogous to PL/pgSQL):
PLSH_TG_NAME
: trigger namePLSH_TG_WHEN
:BEFORE
,INSTEAD OF
, orAFTER
PLSH_TG_LEVEL
:ROW
orSTATEMENT
PLSH_TG_OP
:DELETE
,INSERT
,UPDATE
, orTRUNCATE
PLSH_TG_TABLE_NAME
: name of the table the trigger is acting onPLSH_TG_TABLE_SCHEMA
: schema name of the table the trigger is acting on
In an event trigger procedure, the event trigger data is available to the script through the following environment variables:
PLSH_TG_EVENT
: event namePLSH_TG_TAG
: command tag
PL/sh supports the DO
command. For example:
DO E'#!/bin/sh\nrm -f /tmp/file' LANGUAGE plsh;
You need to have PostgreSQL 8.4 or later, and you need to have the server include files installed.
To build and install PL/sh, use this procedure:
make
make install
The include files are found using the pg_config
program that is
included in the PostgreSQL installation. To use a different
PostgreSQL installation, point configure to a different pg_config
like
so:
make PG_CONFIG=/else/where/pg_config
make install PG_CONFIG=/else/where/pg_config
Note that generally server-side modules such as this one have to be recompiled for every major PostgreSQL version (that is, 8.4, 9.0, ...).
To declare the language in a database, use the extension system with PostgreSQL version 9.1 or later. Run
CREATE EXTENSION plsh;
inside the database of choice. To upgrade from a previous installation that doesn't use the extension system, use
CREATE EXTENSION plsh FROM unpackaged;
Use DROP EXTENSION
to remove it.
With versions prior to PostgreSQL 9.1, use
psql -d DBNAME -f .../share/contrib/plsh.sql
with a server running. To drop it, use droplang plsh
, or DROP FUNCTION plsh_handler(); DROP LANGUAGE plsh;
if you want to do it
manually.
To run the test suite, execute
make installcheck
after installation.