1 files changed, 10 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
index 571edffec7..f9e1e046ea 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
@@ -45,7 +45,17 @@ module ActiveRecord
           indexes
         end
 
+        def internal_string_options_for_primary_key
+          super.tap do |options|
+            if CHARSETS_OF_4BYTES_MAXLEN.include?(charset) && (mariadb? || version < "8.0.0")
+              options[:collation] = collation.sub(/\A[^_]+/, "utf8")
+            end
+          end
+        end
+
         private
+          CHARSETS_OF_4BYTES_MAXLEN = ["utf8mb4", "utf16", "utf16le", "utf32"]
+
           def schema_creation
             MySQL::SchemaCreation.new(self)
           end