hstore_pllua

Overview

Version

Install

You can install pllua directly. First, make sure the PGDG and PIGSTY repositories are added and enabled:

pig repo add pgsql -u          # Add repo and update cache

Install the extension using pig or apt/yum/dnf:

• Install
• pig
• dnf
• apt

pig install pllua;          # Install for current active PG version

pig ext install -y pllua -v 18  # PG 18
pig ext install -y pllua -v 17  # PG 17
pig ext install -y pllua -v 16  # PG 16
pig ext install -y pllua -v 15  # PG 15
pig ext install -y pllua -v 14  # PG 14

dnf install -y pllua_18       # PG 18
dnf install -y pllua_17       # PG 17
dnf install -y pllua_16       # PG 16
dnf install -y pllua_15       # PG 15
dnf install -y pllua_14       # PG 14

apt install -y postgresql-18-pllua   # PG 18
apt install -y postgresql-17-pllua   # PG 17
apt install -y postgresql-16-pllua   # PG 16
apt install -y postgresql-15-pllua   # PG 15
apt install -y postgresql-14-pllua   # PG 14

Create Extension:

CREATE EXTENSION hstore_pllua CASCADE;  -- requires: hstore, pllua

Usage

hstore_pllua: hstore transform for PL/Lua

The hstore_pllua extension provides a transform that allows hstore values to be passed directly to and from PL/Lua functions as native Lua tables, instead of opaque datum objects.

CREATE EXTENSION hstore;
CREATE EXTENSION pllua;
CREATE EXTENSION hstore_pllua;

Using hstore in PL/Lua

With the transform installed, hstore arguments are automatically converted to Lua tables, and Lua tables can be returned as hstore values:

CREATE FUNCTION process_hstore(h hstore) RETURNS hstore LANGUAGE pllua AS $$
  -- h is a Lua table with string keys and string values
  h["new_key"] = "new_value"
  h["modified"] = "true"
  return h
$$;

SELECT process_hstore('name => "Alice", age => "30"'::hstore);

Iterate Over hstore Keys

CREATE FUNCTION hstore_keys(h hstore) RETURNS SETOF text LANGUAGE pllua AS $$
  for k, v in pairs(h) do
    coroutine.yield(k)
  end
$$;

Without this transform, hstore values would need to be manually converted using the hstore type functions.