pltcl

PL/Tcl procedural language

pltcl : PL/Tcl procedural language

Overview

ID	Extension	Package	Version	Category	License	Language
3240	pltcl	pltcl	`1.0`	LANG	PostgreSQL	C

Attribute	Has Binary	Has Library	Need Load	Has DDL	Relocatable	Trusted
--s-dt-	No	Yes	No	Yes	no	yes

Relationships
Schemas	`pg_catalog`
See Also	plperl plperlu plpython3u pljava plsh plr plxslt plpgsql
Siblings	pltclu

Packages

PG18	PG17	PG16	PG15	PG14
1.0	1.0	1.0	1.0	1.0

This is a built-in contrib extension ship with the PostgreSQL kernel

Install

Create this extension with:

CREATE EXTENSION pltcl;

Usage

pltcl: PL/Tcl trusted procedural language

PL/Tcl allows writing PostgreSQL functions in the Tcl programming language. As a trusted language, it restricts access to the filesystem and other system resources.

CREATE EXTENSION pltcl;

-- Simple function returning a greeting
CREATE FUNCTION tcl_hello(name text) RETURNS text
LANGUAGE pltcl AS $$
  return "Hello, $1!"
$$;

SELECT tcl_hello('world');

-- Function with conditional logic
CREATE FUNCTION tcl_max(a integer, b integer) RETURNS integer
LANGUAGE pltcl AS $$
  if {$1 > $2} {return $1}
  return $2
$$;

-- Set-returning function
CREATE FUNCTION tcl_sequence(count integer) RETURNS SETOF integer
LANGUAGE pltcl AS $$
  for {set i 1} {$i <= $1} {incr i} {
    return_next $i
  }
$$;

-- Trigger function
CREATE FUNCTION tcl_audit() RETURNS trigger
LANGUAGE pltcl AS $$
  set NEW(modified_at) [clock format [clock seconds] -format "%Y-%m-%d %H:%M:%S"]
  return [array get NEW]
$$;

Database access from PL/Tcl uses the spi_exec command:

CREATE FUNCTION tcl_count_rows(tbl text) RETURNS integer
LANGUAGE pltcl AS $$
  spi_exec "SELECT count(*) AS cnt FROM $1"
  return $cnt
$$;