Add unique index on summaries and dedup existing records

Author: romanrizzi

app/models/ai_summary.rb

@@ -51,5 +51,6 @@ def outdated
 #
 # Indexes
 #
-#  index_ai_summaries_on_target_type_and_target_id  (target_type,target_id)
+#  idx_on_target_id_target_type_summary_type_3355609fbb  (target_id,target_type,summary_type) UNIQUE
+#  index_ai_summaries_on_target_type_and_target_id       (target_type,target_id)
 #

db/migrate/20241125132452_unique_ai_summaries.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+class UniqueAiSummaries < ActiveRecord::Migration[7.1]
+  def up
+    execute <<~SQL
+      DELETE FROM ai_summaries ais1
+      USING ai_summaries ais2
+      WHERE ais1.id < ais2.id
+        AND ais1.target_id = ais2.target_id
+        AND ais1.target_type = ais2.target_type
+        AND ais1.summary_type = ais2.summary_type
+    SQL
+
+    add_index :ai_summaries, %i[target_id target_type summary_type], unique: true
+  end
+
+  def down
+    remove_index :ai_summaries, column: %i[target_id target_type summary_type]
+  end
+end