2 files changed, 17 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index 65faa80065..5242151736 100755
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -440,6 +440,16 @@ module ActiveRecord
         variables.first['Value'] unless variables.empty?
       end
 
+      # Returns a table's primary key and belonging sequence.
+      def pk_and_sequence_for(table) #:nodoc:
+        table_desc_result = execute("describe #{table}")
+        keys = []
+        execute("describe #{table}").each_hash do |h|
+          keys << h["Field"]if h["Key"] == "PRI"
+        end
+        keys.length == 1 ? [keys.first, nil] : nil
+      end
+
       private
         def connect
           encoding = @config[:encoding]
diff --git a/activerecord/test/schema_dumper_test.rb b/activerecord/test/schema_dumper_test.rb
index fa2b8bdf24..c6041e4f5c 100644
--- a/activerecord/test/schema_dumper_test.rb
+++ b/activerecord/test/schema_dumper_test.rb
@@ -110,6 +110,13 @@ if ActiveRecord::Base.connection.respond_to?(:tables)
         output = standard_dump
         assert_match %r{t.text\s+"body",\s+:default => "",\s+:null => false$}, output
       end
+
+      def test_mysql_schema_dump_should_honor_nonstandard_primary_keys
+        output = standard_dump
+        match = output.match(%r{create_table "movies"(.*)do})
+        assert_not_nil(match, "nonstandardpk table not found")
+        assert_match %r(:primary_key => "movieid"), match[1], "non-standard primary key not preserved"
+      end
     end
 
     def test_schema_dump_includes_decimal_options