Build an HStore-based query index for EAV attributes

delete_eav_from_hstore.sql

CREATE OR REPLACE FUNCTION delete_thing_att_map_hstore()
  RETURNS trigger AS
$BODY$BEGIN
        update 
		thing
	set
		att_map =  ( att_map - OLD.def_id::text )
	WHERE
		id = NEW.thing_id;

RETURN NEW;
END;$BODY$
  LANGUAGE plpgsql VOLATILE

update_eav_to_hstore.sql

CREATE OR REPLACE FUNCTION update_thing_att_map_hstore()
  RETURNS trigger AS
$BODY$BEGIN
        update 
		thing
	set
		att_map =  coalesce(att_map, hstore(array[]::varchar[])) 
				||
			   hstore(NEW.def_id::text, NEW.value::text)
	WHERE
		id = NEW.thing_id;

RETURN NEW;
END;$BODY$
  LANGUAGE plpgsql VOLATILE