--
-- table_log () -- log changes to another table
--
--
-- see README.table_log for details
--
--
-- written by Andreas ' ads' Scherbaum (ads@pgug.de)
--
--

-- drop old trigger
DROP TRIGGER test_log_chg ON test; -- ignore any error

-- create demo table
DROP TABLE test; -- ignore any error
CREATE TABLE test (
  id                    INT                 NOT NULL
                                            PRIMARY KEY,
  name                  VARCHAR(20)         NOT NULL
);

-- create the table without data from demo table
DROP TABLE test_log; -- ignore any error
SELECT * INTO test_log FROM test LIMIT 0;
ALTER TABLE test_log ADD COLUMN trigger_mode VARCHAR(10);
ALTER TABLE test_log ADD COLUMN trigger_tuple VARCHAR(5);
ALTER TABLE test_log ADD COLUMN trigger_changed TIMESTAMPTZ;
ALTER TABLE test_log ADD COLUMN trigger_id BIGINT;
CREATE SEQUENCE test_log_id;
SELECT SETVAL('test_log_id', 1, FALSE);
ALTER TABLE test_log ALTER COLUMN trigger_id SET DEFAULT NEXTVAL('test_log_id');

-- drop old function
DROP FUNCTION table_log (); -- ignore any error
DROP FUNCTION "table_log_restore_table" (VARCHAR, VARCHAR, CHAR, CHAR, CHAR, TIMESTAMPTZ, CHAR, INT, INT);
DROP FUNCTION "table_log_restore_table" (VARCHAR, VARCHAR, CHAR, CHAR, CHAR, TIMESTAMPTZ, CHAR, INT);
DROP FUNCTION "table_log_restore_table" (VARCHAR, VARCHAR, CHAR, CHAR, CHAR, TIMESTAMPTZ, CHAR);
DROP FUNCTION "table_log_restore_table" (VARCHAR, VARCHAR, CHAR, CHAR, CHAR, TIMESTAMPTZ);

-- create function
CREATE FUNCTION table_log ()
    RETURNS TRIGGER
    AS 'MODULE_PATHNAME' LANGUAGE 'C';
CREATE FUNCTION "table_log_restore_table" (VARCHAR, VARCHAR, CHAR, CHAR, CHAR, TIMESTAMPTZ, CHAR, INT, INT)
    RETURNS VARCHAR
    AS 'MODULE_PATHNAME', 'table_log_restore_table' LANGUAGE 'C';
CREATE FUNCTION "table_log_restore_table" (VARCHAR, VARCHAR, CHAR, CHAR, CHAR, TIMESTAMPTZ, CHAR, INT)
    RETURNS VARCHAR
    AS 'MODULE_PATHNAME', 'table_log_restore_table' LANGUAGE 'C';
CREATE FUNCTION "table_log_restore_table" (VARCHAR, VARCHAR, CHAR, CHAR, CHAR, TIMESTAMPTZ, CHAR)
    RETURNS VARCHAR
    AS 'MODULE_PATHNAME', 'table_log_restore_table' LANGUAGE 'C';
CREATE FUNCTION "table_log_restore_table" (VARCHAR, VARCHAR, CHAR, CHAR, CHAR, TIMESTAMPTZ)
    RETURNS VARCHAR
    AS 'MODULE_PATHNAME', 'table_log_restore_table' LANGUAGE 'C';

-- create trigger
CREATE TRIGGER test_log_chg AFTER UPDATE OR INSERT OR DELETE ON test FOR EACH ROW
               EXECUTE PROCEDURE table_log();

-- test trigger
INSERT INTO test VALUES (1, 'name');
SELECT * FROM test;
SELECT * FROM test_log;
UPDATE test SET name='other name' WHERE id=1;
SELECT * FROM test;
SELECT * FROM test_log;

-- create restore table
SELECT table_log_restore_table('test', 'id', 'test_log', 'trigger_id', 'test_recover', NOW());
SELECT * FROM test_recover;