#442

backend/app/models/history_access.rb

@@ -59,20 +59,21 @@ class HistoryAccess < ActiveSupport::CurrentAttributes
   end
 
   def self.json_reference(table, key, document)
-    "NOT EXISTS (SELECT 1 FROM JSON_TABLE(COALESCE(#{ document }, JSON_ARRAY()), " +
+    # A scalar lookup avoids MySQL's semijoin rewrite losing the JSON row correlation.
+    "(SELECT 1 FROM JSON_TABLE(COALESCE(#{ document }, JSON_ARRAY()), " +
         "'$[*]' COLUMNS (reference_id BIGINT PATH '$' NULL ON EMPTY)) reference_entry " +
         "JOIN (#{ discarded_keys(table, key) }) blocked " +
-        "ON reference_entry.reference_id = blocked.#{ key })"
+        "ON reference_entry.reference_id = blocked.#{ key } LIMIT 1) IS NULL"
   end
 
   def self.list_reference(table, key, document)
     # Preserve FIND_IN_SET's exact token semantics, including empty tokens.
     array = "CONCAT('[', REPLACE(JSON_QUOTE(REPLACE(COALESCE(#{ document }, ''), " +
         "' ', ',')), ',', '\",\"'), ']')"
-    "NOT EXISTS (SELECT 1 FROM JSON_TABLE(#{ array }, '$[*]' " +
+    "(SELECT 1 FROM JSON_TABLE(#{ array }, '$[*]' " +
         "COLUMNS (reference_id VARCHAR(255) PATH '$')) reference_entry " +
         "JOIN (#{ discarded_keys(table, key) }) blocked " +
-        "ON reference_entry.reference_id = CAST(blocked.#{ key } AS CHAR))"
+        "ON reference_entry.reference_id = CAST(blocked.#{ key } AS CHAR) LIMIT 1) IS NULL"
   end
 
   def self.snapshot_reference(model, row, external: false)
@@ -91,8 +92,8 @@ class HistoryAccess < ActiveSupport::CurrentAttributes
       match += ' AND reference_version.version_no = tag_reference.version_no'
       latest = ''
     end
-    "NOT EXISTS (SELECT 1 FROM #{ source } JOIN #{ table } reference_version ON #{ match } " +
-        "WHERE NOT (#{ sql(model, 'reference_version') }) #{ latest })"
+    "(SELECT 1 FROM #{ source } JOIN #{ table } reference_version ON #{ match } " +
+        "WHERE NOT (#{ sql(model, 'reference_version') }) #{ latest } LIMIT 1) IS NULL"
   end
 
   def self.reference_sql(table, row)