4 files changed, 41 insertions(+), 0 deletions(-)

A deploy/notify_low_balance.sql
A revert/notify_low_balance.sql
M sqitch.plan
A verify/notify_low_balance.sql

@@ 0,0 1,25 @@
+-- Deploy jmp:notify_low_balance to pg
+-- requires: transactions
+-- requires: balances
+
+BEGIN;
+
+CREATE OR REPLACE FUNCTION check_and_notify_low_balance() RETURNS TRIGGER AS $$
+	DECLARE
+		bal NUMERIC;
+	BEGIN
+		SELECT balance INTO bal FROM balances WHERE customer_id = NEW.customer_id;
+		IF bal < 5 THEN
+			SELECT pg_notify('low_balance', NEW.customer_id);
+		END IF;
+		RETURN NEW;
+	END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER notify_low_balance
+	AFTER INSERT ON transactions
+	FOR EACH ROW
+	WHEN (NEW.amount < 0)
+	EXECUTE PROCEDURE check_and_notify_low_balance();
+
+COMMIT;

@@ 0,0 1,8 @@
+-- Revert jmp:notify_low_balance from pg
+
+BEGIN;
+
+DROP TRIGGER notify_low_balance ON transactions;
+DROP FUNCTION check_and_notify_low_balance;
+
+COMMIT;

@@ 21,3 21,4 @@ plans 2021-11-17T18:06:30Z Stephen Paul Weber,,, <singpolyma@singpolyma-beefy> #
 customers 2021-11-30T16:36:48Z Stephen Paul Weber,,, <singpolyma@singpolyma-beefy> # Get customers from Redis\n\nRequires a redis_server to be configured on the postgres instance.
 cdr_charge [customer_plans plans cdr_with_charge] 2021-11-17T18:09:49Z Stephen Paul Weber,,, <singpolyma@singpolyma-beefy> # Get the amount to charge a customer for a given CDR
 insert_charge_for_cdr [cdr_charge cdr_with_charge transactions] 2021-11-23T14:41:15Z Stephen Paul Weber,,, <singpolyma@singpolyma-beefy> # Trigger to insert a transaction for the charge for this CDR
+notify_low_balance [transactions balances] 2021-12-22T00:36:03Z Stephen Paul Weber,,, <singpolyma@singpolyma-beefy> # NOTIFY when balance dips low

@@ 0,0 1,7 @@
+-- Verify jmp:notify_low_balance on pg
+
+BEGIN;
+
+-- Cannot LISTEN from inside DB
+
+ROLLBACK;