A brief introduction to Postgres Rules

1. Postgres Rules

2. Heresy

3. CREATE RULE

4. Esoteric

5. Y u no use trigger?

6. View

7. View
CREATE TABLE users (
id integer,
name varchar(40),
PRIMARY KEY(did)
);
CREATE VIEW myview AS SELECT * FROM users;

8. View
CREATE TABLE users (
id integer,
name varchar(40),
PRIMARY KEY(did)
);
CREATE VIEW myview AS SELECT * FROM users;
==
CREATE RULE "_RETURN" AS ON SELECT TO myview DO INSTEAD
SELECT * FROM mytab;

9. Speed

10. Warning

11. Warning

13. Qualification given and INSTEAD
the query tree from the rule action with the rule qualification and the original query tree's
qualification; and the original query tree with the negated rule qualification added

14. Qualification given and INSTEAD
the query tree from the rule action with the rule qualification and the original query tree's
qualification; and the original query tree with the negated rule qualification added

16. CREATE TABLE counts (
id INT4 PRIMARY KEY,
count INT4 NOT NULL
);

17. CREATE TABLE counts (
id INT4 PRIMARY KEY,
count INT4 NOT NULL
);
CREATE RULE upsert_counts AS ON INSERT TO counts
WHERE exists ( SELECT * FROM counts WHERE id = NEW.id )
DO INSTEAD UPDATE counts SET count = count + 1 WHERE id = NEW.id;

18. Qualification given and INSTEAD
the query tree from the rule action with the rule qualification and the original query tree's
qualification; and the original query tree with the negated rule qualification added
CREATE TABLE counts (
id INT4 PRIMARY KEY,
count INT4 NOT NULL
);
CREATE RULE upsert_counts AS ON INSERT TO counts
WHERE exists ( SELECT * FROM counts WHERE id = NEW.id )
DO INSTEAD UPDATE counts SET count = count + 1 WHERE id = NEW.id;

19. Qualification given and INSTEAD
the query tree from the rule action with the rule qualification and the original query tree's
qualification; and the original query tree with the negated rule qualification added
CREATE TABLE counts (
id INT4 PRIMARY KEY,
count INT4 NOT NULL
);
CREATE RULE upsert_counts AS ON INSERT TO counts
WHERE exists ( SELECT * FROM counts WHERE id = NEW.id )
DO INSTEAD UPDATE counts SET count = count + 1 WHERE id = NEW.id;

20. Qualification given and INSTEAD
the query tree from the rule action with the rule qualification and the original query tree's
qualification; and the original query tree with the negated rule qualification added
CREATE TABLE counts (
id INT4 PRIMARY KEY,
count INT4 NOT NULL
);
CREATE RULE upsert_counts AS ON INSERT TO counts
WHERE exists ( SELECT * FROM counts WHERE id = NEW.id )
DO INSTEAD UPDATE counts SET count = count + 1 WHERE id = NEW.id;
INSERT INTO counts (id, count) VALUES (1, 1);

21. Qualification given and INSTEAD
the query tree from the rule action with the rule qualification and the original query tree's
qualification; and the original query tree with the negated rule qualification added
CREATE TABLE counts (
id INT4 PRIMARY KEY,
count INT4 NOT NULL
);
CREATE RULE upsert_counts AS ON INSERT TO counts
WHERE exists ( SELECT * FROM counts WHERE id = NEW.id )
DO INSTEAD UPDATE counts SET count = count + 1 WHERE id = NEW.id;
INSERT INTO counts (id, count) VALUES (1, 1); # SELECT * FROM counts;
id | count
----+----------
1 | 2
(1 row)

22. Qualification given and INSTEAD
the query tree from the rule action with the rule qualification and the original query tree's
qualification; and the original query tree with the negated rule qualification added
CREATE TABLE counts (
id INT4 PRIMARY KEY,
count INT4 NOT NULL
);
CREATE RULE upsert_counts AS ON INSERT TO counts
WHERE exists ( SELECT * FROM counts WHERE id = NEW.id )
DO INSTEAD UPDATE counts SET count = count + 1 WHERE id = NEW.id;
INSERT INTO counts (id, count) VALUES (1, 1);
# SELECT * FROM counts;
id | count
----+----------
1 | 2
(1 row)

23. Qualification given and INSTEAD
the query tree from the rule action with the rule qualification and the original query tree's
qualification; and the original query tree with the negated rule qualification added
CREATE TABLE counts (
id INT4 PRIMARY KEY,
count INT4 NOT NULL
);
CREATE RULE upsert_counts AS ON INSERT TO counts
WHERE exists ( SELECT * FROM counts WHERE id = NEW.id )
DO INSTEAD UPDATE counts SET count = count + 1 WHERE id = NEW.id;
INSERT INTO counts (id, count) VALUES (1, 1);
# SELECT * FROM counts;
id | count
BECOMES:
----+----------
INSERT INTO test (id, some_val) 1 | 2
SELECT 1, 1 WHERE NOT ( (1 row)
EXISTS ( SELECT * FROM test WHERE id = 1)
);
UPDATE test
SET some_val = some_val + 1
WHERE id = 1 AND ( EXISTS ( SELECT * FROM test WHERE id = 1 ) );

25. CREATE TABLE test (
id!
! INT4 PRIMARY KEY,
val! INT4 NOT NULL
);

26. CREATE TABLE test (
id!
! INT4 PRIMARY KEY,
val! INT4 NOT NULL
);
CREATE TABLE test_log (
id !! ! INT4 PRIMARY KEY,
creation_date! TIMESTAMP NOT NULL,
val ! ! ! ! INT4 NOT NULL,
! CONSTRAINT test_log_pk PRIMARY KEY(id, creation_date)
);

27. CREATE TABLE test (
id!
! INT4 PRIMARY KEY,
val! INT4 NOT NULL
);
CREATE TABLE test_log (
id !! ! INT4 PRIMARY KEY,
creation_date! TIMESTAMP NOT NULL,
val ! ! ! ! INT4 NOT NULL,
! CONSTRAINT test_log_pk PRIMARY KEY(id, creation_date)
);
CREATE RULE test_logging AS ON INSERT TO test
! DO ALSO INSERT INTO test_log(id, creation_date, val) VALUES(NEW.id, NOW(), NEW.val);

28. CREATE TABLE test (
id!
! INT4 PRIMARY KEY,
val! INT4 NOT NULL
);
CREATE TABLE test_log (
id !! ! INT4 PRIMARY KEY,
creation_date! TIMESTAMP NOT NULL,
val ! ! ! ! INT4 NOT NULL,
! CONSTRAINT test_log_pk PRIMARY KEY(id, creation_date)
);
CREATE RULE test_logging AS ON INSERT TO test
! DO ALSO INSERT INTO test_log(id, creation_date, val) VALUES(NEW.id, NOW(), NEW.val);
INSERT INTO test(id, count) VALUES (1, RANDOM());

29. CREATE TABLE test (
id!
! INT4 PRIMARY KEY,
val! INT4 NOT NULL
);
CREATE TABLE test_log (
id !! ! INT4 PRIMARY KEY,
creation_date! TIMESTAMP NOT NULL,
val ! ! ! ! INT4 NOT NULL,
! CONSTRAINT test_log_pk PRIMARY KEY(id, creation_date)
);
CREATE RULE test_logging AS ON INSERT TO test
! DO ALSO INSERT INTO test_log(id, creation_date, val) VALUES(NEW.id, NOW(), NEW.val);
INSERT INTO test(id, count) VALUES (1, RANDOM());
# SELECT * FROM test;
id | val
----+------
1 | 46228
(1 row)

30. CREATE TABLE test (
id!
! INT4 PRIMARY KEY,
val! INT4 NOT NULL
);
CREATE TABLE test_log (
id !! ! INT4 PRIMARY KEY,
creation_date! TIMESTAMP NOT NULL,
val ! ! ! ! INT4 NOT NULL,
! CONSTRAINT test_log_pk PRIMARY KEY(id, creation_date)
);
CREATE RULE test_logging AS ON INSERT TO test
! DO ALSO INSERT INTO test_log(id, creation_date, val) VALUES(NEW.id, NOW(), NEW.val);
INSERT INTO test(id, count) VALUES (1, RANDOM());
# SELECT * FROM test; # SELECT * FROM test_log;
id | val id | creation_date! ! | val
----+------ ----+--------------------------+-----
1 | 46228 1 | 2012-05-03 07:02:16.43841 15375
(1 row) (1 row)

31. Use Case

32. reconciliations_data
financial_operations
id
id
bank_num
amount
start_count
card_number
end_count
cashier_id
deposit_slip_number
reconciliation_id
cashier_id

33. reconciliations_data
financial_operations
id
id
bank_num
amount
start_count
card_number
end_count
cashier_id
deposit_slip_number
reconciliation_id
cashier_id

35. CREATE OR REPLACE VIEW reconciliations AS
SELECT
! rec.*,
! fin1.id AS start_id,
! fin1.upload_date AS start_date,
! fin2.id AS end_id,
! fin2.upload_date AS end_date
FROM
! reconciliations_data rec
LEFT OUTER JOIN
! (SELECT
DISTINCT
first_value(id) OVER (partition BY reconciliation_id ORDER BY upload_date ASC) AS id,
first_value(upload_date) OVER (partition BY reconciliation_id ORDER BY upload_date ASC) AS upload_date,
reconciliation_id
FROM
financial_operations) AS fin1 ON (fin1.reconciliation_id = rec.id)
LEFT OUTER JOIN
! (SELECT
DISTINCT
first_value(id) OVER (partition BY reconciliation_id ORDER BY upload_date DESC) AS id,
first_value(upload_date) OVER (partition BY reconciliation_id ORDER BY upload_date DESC) AS upload_date,
reconciliation_id
FROM
financial_operations) AS fin2 ON (fin2.reconciliation_id = rec.id)

36. reconciliations_data
financial_operations
id
id
bank_num
amount
start_count
card_number
end_count
cashier_id
deposit_slip_number
reconciliation_id
cashier_id

37. reconciliations_data
financial_operations
id
id
bank_num
amount
start_count
card_number
end_count
cashier_id
deposit_slip_number
reconciliation_id
cashier_id
CREATE OR REPLACE RULE fin_ops_from_recons AS
ON INSERT TO reconciliations DO INSTEAD
( INSERT INTO reconciliations_data (cashier_id, lot_id, lane_id, start_count, end_count, cash_deposited, bank_amount,
bank_returned, deposit_slip_number, created_at, updated_at)
VALUES (new.cashier_id, new.lot_id, new.lane_id, new.start_count, new.end_count, new.cash_deposited, new.bank_amount,
new.bank_returned, new.deposit_slip_number, new.created_at, new.updated_at)
RETURNING
! ! ! currval('reconciliations_id_seq')::integer,
! ! ! cashier_id,
! ! ! lot_id,
! ! ! lane_id,
! ! ! start_count,
! ! ! end_count,
! ! ! cash_deposited,
! ! ! bank_amount,
! ! ! bank_returned,
! ! ! deposit_slip_number,
! ! ! created_at,
! ! ! updated_at,
! ! ! null::varchar,
! ! ! null::varchar,
! ! ! null::timestamp,
! ! ! null::varchar,
! ! ! null::timestamp;
;

38. reconciliations_data
financial_operations
id
id
bank_num
amount
start_count
card_number
end_count
cashier_id
deposit_slip_number
reconciliation_id
cashier_id

39. reconciliations_data
financial_operations
id
id
bank_num
amount
start_count
card_number
end_count
cashier_id
deposit_slip_number
reconciliation_id
cashier_id
UPDATE financial_operations SET reconciliation_id = lastval()
WHERE financial_operations.remote_creation_date >= (( SELECT financial_operations.remote_creation_date
FROM financial_operations
WHERE financial_operations.id::text = new.start_id::text)) AND financial_operations.remote_creation_date <=
(( SELECT financial_operations.remote_creation_date
FROM financial_operations
WHERE financial_operations.id::text = new.end_id::text)) AND financial_operations.order_transaction_id IS NOT NULL
AND
CASE
WHEN new.lot_id IS NULL THEN new.cashier_id::text = (SELECT order_transactions.user_id
FROM order_transactions
WHERE order_transactions.id::text = financial_operations.order_transaction_id::text)::text
ELSE ((new.cashier_id::text, new.lot_id) = ( SELECT order_transactions.user_id, order_transactions.lot_id
FROM order_transactions
WHERE order_transactions.id::text = financial_operations.order_transaction_id::text))
END;
);

40. FIN
guyren@relevantlogic.com