From 9700085a57c738ecf8b3e9d60102ca224794b095 Mon Sep 17 00:00:00 2001
From: Ant Zucaro <azucaro@gmail.com>
Date: Sat, 21 Apr 2012 16:00:27 -0400
Subject: [PATCH] Do a weighted average instead of picking the max.

---
 functions/merge_players.sql | 44 ++++++++++++++++++++++++++-----------
 1 file changed, 31 insertions(+), 13 deletions(-)

diff --git a/functions/merge_players.sql b/functions/merge_players.sql
index f242f3e..aabf164 100644
--- a/functions/merge_players.sql
+++ b/functions/merge_players.sql
@@ -1,7 +1,8 @@
 create or replace function merge_players(p_winner_player_id players.player_id%TYPE, p_loser_player_id players.player_id%TYPE) RETURNS void as
 $$
 declare
-   rowcount integer;   
+   rowcount integer;
+   weighted_elo record;
 begin
    -- start with weapon stats
    update player_weapon_stats
@@ -25,24 +26,41 @@ begin
    where player_id = p_loser_player_id
    and not exists (select 1 from xonstat.player_elos where player_id = p_winner_player_id and game_type_cd = pe.game_type_cd);
 
+   -- take the weighted average of the elos and sum the games to get the new total
+   FOR weighted_elo IN (select game_type_cd, elo_sum/game_count aggregate_elo, game_count
+      from (
+         select game_type_cd, sum(games*elo) elo_sum, sum(games) game_count 
+         from player_elos 
+         where player_id in (p_winner_player_id, p_loser_player_id) 
+         group by game_type_cd
+      ) es)
+   LOOP
+      update xonstat.player_elos
+      set elo = weighted_elo.aggregate_elo, games = weighted_elo.game_count
+      where player_id = p_winner_player_id
+      and game_type_cd = weighted_elo.game_type_cd;
+
+      raise notice 'New % Elo is %.', weighted_elo.game_type_cd, weighted_elo.aggregate_elo;
+   END LOOP;
+
    -- update the existing player_elos entries that have a higher elo on the loser
-   update xonstat.player_elos pe
-   set elo = newpe.elo
-   from
-      (select lpe.game_type_cd, lpe.elo
-      from xonstat.player_elos wpe, xonstat.player_elos lpe
-      where wpe.game_type_cd = lpe.game_type_cd
-      and wpe.player_id = 67
-      and lpe.player_id = 720
-      and lpe.elo > wpe.elo) newpe
-   where player_id = 67
-   and pe.game_type_cd = newpe.game_type_cd;
+   -- update xonstat.player_elos pe
+   -- set elo = newpe.elo
+   -- from
+      -- (select lpe.game_type_cd, lpe.elo
+      -- from xonstat.player_elos wpe, xonstat.player_elos lpe
+      -- where wpe.game_type_cd = lpe.game_type_cd
+      -- and wpe.player_id = 67
+      -- and lpe.player_id = 720
+      -- and lpe.elo > wpe.elo) newpe
+   -- where player_id = 67
+   -- and pe.game_type_cd = newpe.game_type_cd;
 
    -- then hashkeys (winner takes the loser's hashkey)
    update hashkeys
    set player_id = p_winner_player_id
    where player_id = p_loser_player_id;
-   
+
    get diagnostics rowcount = ROW_COUNT;
    raise notice '% hashkeys copied.', rowcount;
 
-- 
2.39.2