fix: solve atomic conflict

Author: Bulletdev

app/modules/ai_intelligence/jobs/rebuild_champion_matrix_job.rb

@@ -8,17 +8,21 @@ class RebuildChampionMatrixJob < ApplicationJob
     queue_as :low_priority
 
     def perform(scope: :all, league: nil)
-      lock_key = "sidekiq:rebuild_champion_matrix:lock"
-      acquired = Sidekiq.redis { |r| r.call("SET", lock_key, "1", "NX", "EX", 3600) }
+      lock_key = 'sidekiq:rebuild_champion_matrix:lock'
+      acquired = Sidekiq.redis { |r| r.call('SET', lock_key, '1', 'NX', 'EX', 3600) }
 
       unless acquired
-        Rails.logger.info("[AI] RebuildChampionMatrixJob skipped — already running")
+        Rails.logger.info('[AI] RebuildChampionMatrixJob skipped — already running')
         return
       end
 
+      # 31k+ records with per-row upserts exceed the default 10s statement_timeout.
+      # Scope this to the current session only — the connection returns to the pool
+      # with its normal timeout restored after the job finishes.
+      ActiveRecord::Base.connection.execute('SET LOCAL statement_timeout = 0')
       rebuild_matrices(scope:, league:)
     ensure
-      Sidekiq.redis { |r| r.call("DEL", lock_key) } if acquired
+      Sidekiq.redis { |r| r.call('DEL', lock_key) } if acquired
     end
 
     private

app/modules/ai_intelligence/models/ai_champion_matrix.rb

@@ -9,11 +9,24 @@ class AiChampionMatrix < ApplicationRecord
   scope :with_sufficient_sample, -> { where('total_games >= ?', 10) }
 
   def self.upsert_win(winner, loser, patch: nil, league: nil)
-    matrix = find_or_initialize_by(champion_a: winner, champion_b: loser, patch: patch, league: league)
-    matrix.wins_a      = matrix.wins_a.to_i + 1
-    matrix.total_games = matrix.total_games.to_i + 1
-    matrix.updated_at  = Time.current
-    matrix.save!
+    # Two separate partial indexes cover the two cases:
+    # - both null  → index_ai_champion_matrices_null_pair
+    # - both present → index_ai_champion_matrices_unique
+    index = if patch.nil? && league.nil?
+              :index_ai_champion_matrices_null_pair
+            else
+              :index_ai_champion_matrices_unique
+            end
+    upsert(
+      { champion_a: winner, champion_b: loser, patch: patch, league: league,
+        wins_a: 1, total_games: 1, updated_at: Time.current },
+      unique_by: index,
+      on_duplicate: Arel.sql(
+        'wins_a = ai_champion_matrices.wins_a + 1, ' \
+        'total_games = ai_champion_matrices.total_games + 1, ' \
+        'updated_at = excluded.updated_at'
+      )
+    )
   end
 
   def win_rate

app/modules/ai_intelligence/services/champion_matrix_builder.rb

@@ -43,12 +43,14 @@ def register_matchups(winner_picks, loser_picks)
   end
 
   def record_appearance(champion_a, champion_b)
-    AiChampionMatrix
-      .find_or_initialize_by(champion_a:, champion_b:)
-      .tap do |m|
-      m.total_games = m.total_games.to_i + 1
-      m.updated_at = Time.current
-      m.save!
-    end
+    AiChampionMatrix.upsert(
+      { champion_a: champion_a, champion_b: champion_b, patch: nil, league: nil,
+        wins_a: 0, total_games: 1, updated_at: Time.current },
+      unique_by: :index_ai_champion_matrices_null_pair,
+      on_duplicate: Arel.sql(
+        'total_games = ai_champion_matrices.total_games + 1, ' \
+        'updated_at = excluded.updated_at'
+      )
+    )
   end
 end

db/migrate/20260424000001_add_null_pair_index_to_ai_champion_matrices.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class AddNullPairIndexToAiChampionMatrices < ActiveRecord::Migration[7.1]
+  def change
+    # Partial index covering rows where both patch and league are NULL.
+    # The existing index_ai_champion_matrices_unique only covers non-null patch+league.
+    # Without this, upsert with ON CONFLICT cannot target the null-patch/league rows.
+    add_index :ai_champion_matrices, %i[champion_a champion_b],
+              name: 'index_ai_champion_matrices_null_pair',
+              unique: true,
+              where: 'patch IS NULL AND league IS NULL'
+  end
+end