fix: batch standings updates to eliminate N+1 queries in recalculate (#75)

Replace per-game update_standings() calls with pre-fetched dicts and
in-memory accumulation, then a single bulk_update at the end.
Reduces ~1,100+ queries for a full season to ~5 queries.

Closes #75

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/db_engine.py

@@ -1317,13 +1317,137 @@ class Standings(BaseModel):
             with db.atomic():
                 Standings.bulk_create(create_teams)
 
-            # Iterate through each individual result
+            # Pre-fetch all data needed for in-memory processing (avoids N+1 queries)
+            standings_by_team_id = {
+                s.team_id: s
+                for s in Standings.select().where(Standings.team << s_teams)
+            }
+            teams_by_id = {t.id: t for t in Team.select().where(Team.season == season)}
+            divisions_by_id = {
+                d.id: d
+                for d in Division.select().where(Division.season == season)
+            }
+
+            # Iterate through each individual result, tallying wins/losses in memory
             # for game in Result.select_season(season).where(Result.week <= 22):
             for game in StratGame.select().where(
                     (StratGame.season == season) & (StratGame.week <= 18) & (StratGame.game_num.is_null(False))
             ).order_by(StratGame.week, StratGame.game_num):
-                # tally win and loss for each standings object
+                away_stan = standings_by_team_id.get(game.away_team_id)
-                game.update_standings()
+                home_stan = standings_by_team_id.get(game.home_team_id)
+                away_team_obj = teams_by_id.get(game.away_team_id)
+                home_team_obj = teams_by_id.get(game.home_team_id)
+                if None in (away_stan, home_stan, away_team_obj, home_team_obj):
+                    continue
+                away_div = divisions_by_id.get(away_team_obj.division_id)
+                home_div = divisions_by_id.get(home_team_obj.division_id)
+                if away_div is None or home_div is None:
+                    continue
+
+                # Home Team Won
+                if game.home_score > game.away_score:
+                    home_stan.wins += 1
+                    home_stan.home_wins += 1
+                    away_stan.losses += 1
+                    away_stan.away_losses += 1
+
+                    if home_stan.streak_wl == 'w':
+                        home_stan.streak_num += 1
+                    else:
+                        home_stan.streak_wl = 'w'
+                        home_stan.streak_num = 1
+
+                    if away_stan.streak_wl == 'l':
+                        away_stan.streak_num += 1
+                    else:
+                        away_stan.streak_wl = 'l'
+                        away_stan.streak_num = 1
+
+                    if game.home_score == game.away_score + 1:
+                        home_stan.one_run_wins += 1
+                        away_stan.one_run_losses += 1
+
+                    if away_div.division_abbrev == 'TC':
+                        home_stan.div1_wins += 1
+                    elif away_div.division_abbrev == 'ETSOS':
+                        home_stan.div2_wins += 1
+                    elif away_div.division_abbrev == 'APL':
+                        home_stan.div3_wins += 1
+                    elif away_div.division_abbrev == 'BBC':
+                        home_stan.div4_wins += 1
+
+                    if home_div.division_abbrev == 'TC':
+                        away_stan.div1_losses += 1
+                    elif home_div.division_abbrev == 'ETSOS':
+                        away_stan.div2_losses += 1
+                    elif home_div.division_abbrev == 'APL':
+                        away_stan.div3_losses += 1
+                    elif home_div.division_abbrev == 'BBC':
+                        away_stan.div4_losses += 1
+
+                    home_stan.run_diff += game.home_score - game.away_score
+                    away_stan.run_diff -= game.home_score - game.away_score
+                # Away Team Won
+                else:
+                    home_stan.losses += 1
+                    home_stan.home_losses += 1
+                    away_stan.wins += 1
+                    away_stan.away_wins += 1
+
+                    if home_stan.streak_wl == 'l':
+                        home_stan.streak_num += 1
+                    else:
+                        home_stan.streak_wl = 'l'
+                        home_stan.streak_num = 1
+
+                    if away_stan.streak_wl == 'w':
+                        away_stan.streak_num += 1
+                    else:
+                        away_stan.streak_wl = 'w'
+                        away_stan.streak_num = 1
+
+                    if game.away_score == game.home_score + 1:
+                        home_stan.one_run_losses += 1
+                        away_stan.one_run_wins += 1
+
+                    if away_div.division_abbrev == 'TC':
+                        home_stan.div1_losses += 1
+                    elif away_div.division_abbrev == 'ETSOS':
+                        home_stan.div2_losses += 1
+                    elif away_div.division_abbrev == 'APL':
+                        home_stan.div3_losses += 1
+                    elif away_div.division_abbrev == 'BBC':
+                        home_stan.div4_losses += 1
+
+                    if home_div.division_abbrev == 'TC':
+                        away_stan.div1_wins += 1
+                    elif home_div.division_abbrev == 'ETSOS':
+                        away_stan.div2_wins += 1
+                    elif home_div.division_abbrev == 'APL':
+                        away_stan.div3_wins += 1
+                    elif home_div.division_abbrev == 'BBC':
+                        away_stan.div4_wins += 1
+
+                    home_stan.run_diff -= game.away_score - game.home_score
+                    away_stan.run_diff += game.away_score - game.home_score
+
+            # Bulk save all modified standings
+            with db.atomic():
+                Standings.bulk_update(
+                    list(standings_by_team_id.values()),
+                    fields=[
+                        Standings.wins, Standings.losses,
+                        Standings.home_wins, Standings.home_losses,
+                        Standings.away_wins, Standings.away_losses,
+                        Standings.one_run_wins, Standings.one_run_losses,
+                        Standings.streak_wl, Standings.streak_num,
+                        Standings.run_diff,
+                        Standings.div1_wins, Standings.div1_losses,
+                        Standings.div2_wins, Standings.div2_losses,
+                        Standings.div3_wins, Standings.div3_losses,
+                        Standings.div4_wins, Standings.div4_losses,
+                    ]
+                )
 
         # Set pythag record and iterate through last 8 games for last8 record
         for team in all_teams: