Redesign initial table design to be more idiomatic

- Use generated identity columns rather than the serial data type.
- Add a sequence order column for each set to keep track of relative
  order and combine that with the foreign key id to represent the
  primary key.
- Add a missing date column for each log entry.
- Mark the combination of user id and exercise name as unique.

Migrations/Scripts/postgres_migration.sql

@@ -1,46 +1,55 @@
 CREATE TABLE bot_user
 (
-    id         SERIAL PRIMARY KEY,
+    id         INTEGER PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
     discord_id VARCHAR(64) UNIQUE NOT NULL
 );
 
 CREATE TYPE exercise_type as ENUM ('set', 'speed', 'time');
 
+-- Users have exercises, but not multiple of the same
 CREATE TABLE exercise
 (
-    id          SERIAL PRIMARY KEY,
+    id          INTEGER PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
     name        VARCHAR(100)  NOT NULL,
     type        exercise_type NOT NULL,
-    bot_user_id INT           NOT NULL REFERENCES bot_user (id)
+    bot_user_id INT           NOT NULL REFERENCES bot_user (id),
+
+    UNIQUE (bot_user_id, name)
 );
 
+-- Exercises are logged on a particular day, referencing a particular exercise
 CREATE TABLE
     exercise_log
 (
-    id          SERIAL PRIMARY KEY,
-    exercise_id INT NOT NULL REFERENCES exercise (id)
+    id          INTEGER PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
+    exercise_id INT  NOT NULL REFERENCES exercise (id),
+    log_date    DATE NOT NULL DEFAULT CURRENT_DATE
 );
 
+-- Represents all sets for a particular log, e.g 1 warmup set + 3x8 regular sets
 CREATE TABLE
     all_set_detail
 (
-    id INT PRIMARY KEY REFERENCES exercise_log (id)
+    id INTEGER PRIMARY KEY REFERENCES exercise_log (id)
 );
 
+-- Represents a single exercise set
 CREATE TABLE
     set_exercise_detail
 (
-    id                SERIAL PRIMARY KEY,
+    id                INTEGER NOT NULL REFERENCES all_set_detail (id),
     reps              INT     NOT NULL,
     weight            INT     NOT NULL,
     is_warmup         BOOLEAN NOT NULL,
-    all_set_detail_id INT     NOT NULL REFERENCES all_set_detail (id)
+    sequence_order    INT     NOT NULL,
+
+    PRIMARY KEY (id, sequence_order)
 );
 
 CREATE TABLE
     speed_exercise_detail
 (
-    id              INT PRIMARY KEY REFERENCES exercise_log (id),
+    id              INTEGER PRIMARY KEY REFERENCES exercise_log (id),
     duration_sec    INT  NOT NULL,
     distance_miles  REAL NOT NULL,
     exercise_log_id INT  NOT NULL
@@ -49,7 +58,7 @@ CREATE TABLE
 CREATE TABLE
     time_exercise_details
 (
-    id              INT PRIMARY KEY REFERENCES exercise_log (id),
+    id              INTEGER PRIMARY KEY REFERENCES exercise_log (id),
     duration_sec    INT NOT NULL,
     exercise_log_id INT NOT NULL
 );