2 files changed, 6 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index 7cc5e666af..99fa9b7d29 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -571,6 +571,9 @@ module ActiveRecord
       #   rename_index :people, 'index_people_on_last_name', 'index_users_on_last_name'
       #
       def rename_index(table_name, old_name, new_name)
+        if new_name.length > allowed_index_name_length
+          raise ArgumentError, "Index name '#{new_name}' on table '#{table_name}' is too long; the limit is #{allowed_index_name_length} characters"
+        end
         # this is a naive implementation; some DBs may support this more efficiently (Postgres, for instance)
         old_index_def = indexes(table_name).detect { |i| i.name == old_name }
         return unless old_index_def
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
index 51853c6812..b4b066c06e 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -478,6 +478,9 @@ module ActiveRecord
         end
 
         def rename_index(table_name, old_name, new_name)
+          if new_name.length > allowed_index_name_length
+            raise ArgumentError, "Index name '#{new_name}' on table '#{table_name}' is too long; the limit is #{allowed_index_name_length} characters"
+          end
           execute "ALTER INDEX #{quote_column_name(old_name)} RENAME TO #{quote_table_name(new_name)}"
         end