[PL/Lua] (https://github.com/pllua/pllua) fork for implementing new PL/Lua features, not properly tested.

Requirements: Postgres 9.4, lua 5.1.

####hstore type support

example:

do $$
  register_type('hstore')
  local hs = fromstring('hstore','"aa"=>"bb"') 
  hs = hstore.delete(fromstring('hstore','a=>1 , b=>2, c=>3'), 'd')
  print(hs)
  hs.a = "foo"
  hs.f = "bar"
  print(hs)
$$ LANGUAGE pllua;

hstore.delete - only one function added to lua to test binding to hstore lib ####pgfunc function

pgfunc might be used to bind postgres functions(sql/internal functions with IN arguments)

example:

do $$
local quote_ident = pgfunc("quote_ident(text)")
print(quote_ident("int"))
$$ LANGUAGE pllua;

wrap sql function:

CREATE OR REPLACE FUNCTION add_em(integer, integer)
  RETURNS integer AS
$BODY$
    SELECT $1 + $2;
$BODY$  LANGUAGE sql;

do $$
local add_em = pgfunc("add_em(integer, integer)")
print  (add_em(5,10));
$$ LANGUAGE pllua;

pgfunc might be used as chunk loader for pllua functions with signature function(internal) internal :

at first we need to register module as postgres function:

CREATE OR REPLACE FUNCTION i_void(internal)
  RETURNS internal AS
$BODY$
-- mymodule.lua
local M = {} -- public interface

-- private
local x = 1
local function baz() print 'test' end

function M.foo() print("foo", x) end

function M.bar()
  M.foo()
  baz()
  print "bar"
end

return M

$BODY$
  LANGUAGE pllua

load and use this code:

do $$
local m_void = pgfunc("i_void(internal)")
m_void.bar()
$$ LANGUAGE pllua;

hstore is not full implemented in pllua, but pgfunc might be used to add additional functionality. hstore.delete - function might be created in pllua dynamically:

do $$
  register_type('hstore')
  local hs_delete = pgfunc("delete(hstore,text)")
  local hs = hs_delete(fromstring('hstore','a=>1 , b=>2, c=>3'), 'b')
  print(hs)
$$ language pllua 

C functions, that use SPI and used through pgfunc may fail in this case.

####subtransactions

example:

do $$
local f = function() 
  local p = server.prepare("UPDATE accounts SET balance = balance + $2 WHERE account_name = $1", {"text","int4"})
  p:execute{'joe', 50}
  p:execute{'mary',-50}
  return true
end  
local status, err = subtransaction(f)
print(status, err)
$$ LANGUAGE pllua;

note: all plans used in subtransaction better be created inside subtransaction function, otherwise it might crash(or not, needs test)

Copyright (c) 2008 Luis Carvalho

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.