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Transaction as foreign key. Example usage.

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This commit is contained in:
Michael Hierweck 2019-05-04 10:24:29 +02:00
parent f40a574ec3
commit 1e0d34306c
1 changed files with 58 additions and 35 deletions
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93
sql/history-demo.sql
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@ -1,17 +1,33 @@
--
-- Historization
--
CREATE TABLE history (
history_id serial PRIMARY KEY,
history_transaction bigint NOT NULL UNIQUE,
history_timestamp timestamp NOT NULL
);
CREATE FUNCTION historicize() RETURNS trigger
AS $$
BEGIN
IF (TG_OP = 'INSERT') OR (TG_OP = 'UPDATE') THEN
EXECUTE format('INSERT INTO %I_history VALUES (DEFAULT, now(), txid_current(), False, $1.*)', TG_TABLE_NAME) USING NEW;
EXECUTE 'INSERT INTO history VALUES (DEFAULT, txid_current(), now()) ON CONFLICT DO NOTHING';
EXECUTE format('INSERT INTO %I_history VALUES (DEFAULT, txid_current(), False, $1.*)', TG_TABLE_NAME) USING NEW;
RETURN NEW;
ELSE
EXECUTE format('INSERT INTO %I_history VALUES (DEFAULT, now(), txid_current(), True, $1.*)', TG_TABLE_NAME) USING OLD;
EXECUTE 'INSERT INTO history VALUES (DEFAULT, txid_current(), now()) ON CONFLICT DO NOTHING';
EXECUTE format('INSERT INTO %I_history VALUES (DEFAULT, txid_current(), True, $1.*)', TG_TABLE_NAME) USING OLD;
RETURN OLD;
END IF;
END;
$$
LANGUAGE plpgsql;
--
-- Entity with History
--
CREATE TABLE person (
id serial PRIMARY KEY,
name character varying(50) NOT NULL UNIQUE,
@ -20,8 +36,7 @@ CREATE TABLE person (
CREATE TABLE person_history (
history_id serial PRIMARY KEY,
history_timestamp timestamp NOT NULL,
history_transaction bigint NOT NULL,
history_transaction bigint NOT NULL REFERENCES history(history_transaction),
history_tombstone boolean NOT NULL,
id integer NOT NULL,
name character varying(50) NOT NULL,
@ -30,37 +45,9 @@ CREATE TABLE person_history (
CREATE TRIGGER person_historicize AFTER INSERT OR DELETE OR UPDATE ON person FOR EACH ROW EXECUTE PROCEDURE historicize();
CREATE OR REPLACE FUNCTION person_history(transaction bigint, VARIADIC groupby text[]) RETURNS TABLE (
history_id integer,
history_timestamp timestamp,
history_transaction bigint,
history_tombstone boolean,
id integer,
name character varying(50),
email character varying(50)
)
AS $$
BEGIN
RETURN QUERY EXECUTE format('SELECT * FROM person_history WHERE history_id IN (SELECT max(history_id) AS history_id FROM person_history WHERE history_transaction <= $1 GROUP BY %s)', array_to_string(groupby, ', ')) USING transaction;
END;
$$
LANGUAGE plpgsql;
CREATE OR REPLACE FUNCTION person_history(VARIADIC groupby text[]) RETURNS TABLE (
history_id integer,
history_timestamp timestamp,
history_transaction bigint,
history_tombstone boolean,
id integer,
name character varying(50),
email character varying(50)
)
AS $$
BEGIN
RETURN QUERY EXECUTE format('SELECT * FROM person_history WHERE history_id IN (SELECT max(history_id) AS history_id FROM person_history GROUP BY %s)', array_to_string(groupby, ', '));
END;
$$
LANGUAGE plpgsql;
--
-- Sample data
--
INSERT INTO person (name, email) VALUES ('michael', 'michael@hierweck.de');
INSERT INTO person (name, email) VALUES ('annika', 'annika@hierweck.de');
@ -80,3 +67,39 @@ INSERT INTO person (name, email) VALUES ('ax', 'ax@hierweck.de');
UPDATE person SET email='mxx@hierweck.de' WHERE name='mx';
UPDATE person SET email='axx@hierweck.de' WHERE name='ax';
COMMIT;
--
-- Approach 1: Function
--
--
-- Usage:
--
-- SELECT * FROM person_history(12345, 'name');
--
CREATE OR REPLACE FUNCTION person_history(transaction bigint, VARIADIC groupby text[]) RETURNS TABLE (
history_id integer,
history_transaction bigint,
history_tombstone boolean,
id integer,
name character varying(50),
email character varying(50)
)
AS $$
BEGIN
RETURN QUERY EXECUTE format('SELECT * FROM person_history WHERE history_id IN (SELECT max(history_id) AS history_id FROM person_history WHERE history_transaction <= $1 GROUP BY %s)', array_to_string(groupby, ', ')) USING transaction;
END;
$$
LANGUAGE plpgsql;
--
-- Approach 2: View
--
-- Usage:
--
-- SET history_transaction = 12345;
-- SELECT * FROM person_history_view;
--
CREATE VIEW person_history_view
AS (SELECT * FROM person_history WHERE history_id IN (SELECT max(history_id) AS history_id FROM person_history WHERE history_transaction <= current_setting('history.transaction')::bigint GROUP BY name));