cache a user's takes in a new column of the participants table

branch.sql

@@ -0,0 +1,50 @@
+BEGIN;
+
+    ALTER TABLE participants ADD COLUMN takes numeric(35,2) NOT NULL DEFAULT 0;
+
+    CREATE TEMPORARY TABLE temp_teams AS
+        SELECT username, receiving
+          FROM participants
+         WHERE "number" = 'plural';
+
+    CREATE TEMPORARY TABLE temp_takes
+    ( team text
+    , member text
+    , amount numeric(35,2)
+    );
+
+    CREATE FUNCTION process_take() RETURNS trigger AS $$
+        DECLARE
+            actual_amount numeric(35,2);
+            team_balance numeric(35,2);
+        BEGIN
+            team_balance := (
+                SELECT receiving
+                  FROM temp_teams
+                 WHERE username = NEW.team
+            );
+            actual_amount := NEW.amount;
+            IF (team_balance < NEW.amount) THEN
+                actual_amount := team_balance;
+            END IF;
+            UPDATE participants
+               SET takes = (takes + actual_amount)
+                 , receiving = (receiving + actual_amount)
+             WHERE username = NEW.member;
+            UPDATE temp_teams
+               SET receiving = (receiving - actual_amount)
+             WHERE username = NEW.team;
+            RETURN NULL;
+        END;
+    $$ LANGUAGE plpgsql;
+
+    CREATE TRIGGER process_take AFTER INSERT ON temp_takes
+        FOR EACH ROW EXECUTE PROCEDURE process_take();
+
+    INSERT INTO temp_takes
+        SELECT team, member, amount
+          FROM current_takes t
+         WHERE t.amount > 0
+      ORDER BY ctime DESC;
+
+END;