Use `utf8mb4` charset for internal tables if the row format `DYNAMIC` by default

The indexing issue on `utf8mb4` columns is resolved since MySQL 5.7.9.

2 files changed, 10 insertions, 10 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index 2d7f34ef24..dbc6614b93 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -116,14 +116,6 @@ module ActiveRecord
         true
       end
 
-      def supports_longer_index_key_prefix?
-        if mariadb?
-          version >= "10.2.2"
-        else
-          version >= "5.7.9"
-        end
-      end
-
       def get_advisory_lock(lock_name, timeout = 0) # :nodoc:
         query_value("SELECT GET_LOCK(#{quote(lock_name.to_s)}, #{timeout})") == 1
       end
@@ -250,7 +242,7 @@ module ActiveRecord
           execute "CREATE DATABASE #{quote_table_name(name)} DEFAULT COLLATE #{quote_table_name(options[:collation])}"
         elsif options[:charset]
           execute "CREATE DATABASE #{quote_table_name(name)} DEFAULT CHARACTER SET #{quote_table_name(options[:charset])}"
-        elsif supports_longer_index_key_prefix?
+        elsif row_format_dynamic_by_default?
           execute "CREATE DATABASE #{quote_table_name(name)} DEFAULT CHARACTER SET `utf8mb4`"
         else
           raise "Configure a supported :charset and ensure innodb_large_prefix is enabled to support indexes on varchar(255) string columns."
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 4894fd1c08..66db4e4149 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb
@@ -79,7 +79,7 @@ module ActiveRecord
 
         def internal_string_options_for_primary_key
           super.tap do |options|
-            if CHARSETS_OF_4BYTES_MAXLEN.include?(charset) && (mariadb? || version < "8.0.0")
+            if !row_format_dynamic_by_default? && CHARSETS_OF_4BYTES_MAXLEN.include?(charset)
               options[:collation] = collation.sub(/\A[^_]+/, "utf8")
             end
           end
@@ -96,6 +96,14 @@ module ActiveRecord
         private
           CHARSETS_OF_4BYTES_MAXLEN = ["utf8mb4", "utf16", "utf16le", "utf32"]
 
+          def row_format_dynamic_by_default?
+            if mariadb?
+              version >= "10.2.2"
+            else
+              version >= "5.7.9"
+            end
+          end
+
           def schema_creation
             MySQL::SchemaCreation.new(self)
           end