ActiveRecord SQL Server Adapter

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About The Adapter

The SQL Server adapter for ActiveRecord using SQL Server 2012 or higher.

We follow a rational versioning policy that tracks Rails. That means that our 7.x version of the adapter is only for the latest 7.x version of Rails. We also have stable branches for each major/minor release of ActiveRecord.

We support the versions of the adapter that are in the Rails Bug Fixes maintenance group.

See Rubygems for the latest version of the adapter for each Rails release.

Adapter Version	Rails Version	Support	Branch
Unreleased	8.1.x	In Development	main
8.0.x	8.0.x	Active	8-0-stable
7.2.x	7.2.x	Active	7-2-stable
7.1.x	7.1.x	Active	7-1-stable
7.0.x	7.0.x	Ended	7-0-stable
6.1.x	6.1.x	Ended	6-1-stable
6.0.x	6.0.x	Ended	6-0-stable
5.2.x	5.2.x	Ended	5-2-stable
5.1.x	5.1.x	Ended	5-1-stable
4.2.x	4.2.x	Ended	4-2-stable
4.1.x	4.1.x	Ended	4-1-stable

Native Data Type Support

We support every data type supported by FreeTDS. All simplified Rails types in migrations will correspond to a matching SQL Server national (unicode) data type. Always check the initialize_native_database_types (here) for an updated list.

The following types (date, datetime2, datetimeoffset, time) all require TDS version 7.3 with TinyTDS. We recommend using FreeTDS 1.0 or higher which default to using TDSVER to 7.3. The adapter also sets TinyTDS's tds_version to this as well if non is specified.

The adapter supports ActiveRecord's datetime_with_precision setting. This means that passing :precision to a datetime column is supported.

By default, precision 6 is used for :datetime types if precision is not specified. Any non-nil precision will tell the adapter to use the datetime2 column type. To create a datetime column using a migration a precision of nil should be specified, otherwise the precision will default to 6 and a datetime2 column will be created.

Identity Inserts with Triggers

The adapter uses OUTPUT INSERTED so that we can select any data type key, for example UUID tables. However, this poses a problem with tables that use triggers. The solution requires that we use a more complex insert statement which uses a temporary table to select the inserted identity. To use this format you must declare your table exempt from the simple output inserted style with the table name into a concurrent hash. Optionally, you can set the data type of the table's primary key to return.

adapter = ActiveRecord::ConnectionAdapters::SQLServerAdapter

# Will assume `bigint` as the id key temp table type.
adapter.exclude_output_inserted_table_names['my_table_name'] = true

# Explicitly set the data type for the temporary key table.
adapter.exclude_output_inserted_table_names['my_uuid_table_name'] = 'uniqueidentifier'


# Explicitly set data types when data type is different for composite primary keys.
adapter.exclude_output_inserted_table_names['my_composite_pk_table_name'] = { pk_col_one: "uniqueidentifier", pk_col_two: "int" }

Force Schema To Lowercase

Although it is not necessary, the Ruby convention is to use lowercase method names. If your database schema is in upper or mixed case, we can force all table and column names during the schema reflection process to be lowercase. Add this to your config/initializers file for the adapter.

ActiveRecord::ConnectionAdapters::SQLServerAdapter.lowercase_schema_reflection = true

Schemas & Users

Depending on your user and schema setup, it may be needed to use a table name prefix of dbo.. So something like this in your initializer file for ActiveRecord or the adapter.

ActiveRecord::Base.table_name_prefix = 'dbo.'

It's also possible to create/change/drop a schema in the migration file as in the example below:

class CreateFooSchema < ActiveRecord::Migration[7.0]
  def up
    create_schema('foo')

    # Or you could move a table to a different schema

    change_table_schema('foo', 'dbo.admin')
  end

  def down
    drop_schema('foo')
  end
end

Configure Connection

The adapter conforms to the AbstractAdapter interface to configure connections. If you require additional connection configuration then implement the configure_connection method in an initializer like so. In the following example we are setting the TEXTSIZE to 64 megabytes.

ActiveRecord::ConnectionAdapters::SQLServerAdapter.prepend(
  Module.new do
    def configure_connection
      super
      @raw_connection.execute("SET TEXTSIZE #{64.megabytes}").do
    end
  end
)

Configure Application Name

TinyTDS supports an application name when it logs into SQL Server. This can be used to identify the connection in SQL Server's activity monitor. By default it will use the appname from your database.yml file or your Rails::Application name.

Below shows how you might use the database.yml file to use the process ID in your application name.

development:
  adapter: sqlserver
  appname: <%= "myapp_#{Process.pid}" %>

Executing Stored Procedures

Every class that sub classes ActiveRecord::Base will now have an execute_procedure class method to use. This method takes the name of the stored procedure which can be a string or symbol and any number of variables to pass to the procedure. Arguments will automatically be quoted per the connection's standards as normal. For example:

Account.execute_procedure(:update_totals, 'admin', nil, true)
# Or with named parameters.
Account.execute_procedure(:update_totals, named: 'params')

Explain Support (SHOWPLAN)

The 3.2 version of the adapter support ActiveRecord's explain features. In SQL Server, this is called the showplan. By default we use the SHOWPLAN_ALL option and format it using a simple table printer. So the following ruby would log the plan table below it.

Car.where(id: 1).explain

EXPLAIN for: SELECT [cars].* FROM [cars] WHERE [cars].[id] = 1
+----------------------------------------------------+--------+--------+--------+----------------------+----------------------+----------------------------------------------------+----------------------------------------------------+--------------+---------------------+----------------------+------------+---------------------+----------------------------------------------------+----------+----------+----------+--------------------+
| StmtText                                           | StmtId | NodeId | Parent | PhysicalOp           | LogicalOp            | Argument                                           | DefinedValues                                      | EstimateRows | EstimateIO          | EstimateCPU          | AvgRowSize | TotalSubtreeCost    | OutputList                                         | Warnings | Type     | Parallel | EstimateExecutions |
+----------------------------------------------------+--------+--------+--------+----------------------+----------------------+----------------------------------------------------+----------------------------------------------------+--------------+---------------------+----------------------+------------+---------------------+----------------------------------------------------+----------+----------+----------+--------------------+
| SELECT [cars].* FROM [cars] WHERE [cars].[id] = 1  |      1 |      1 |      0 | NULL                 | NULL                 | 2                                                  | NULL                                               |          1.0 | NULL                | NULL                 | NULL       | 0.00328309996984899 | NULL                                               | NULL     | SELECT   | false    | NULL               |
|   |--Clustered Index Seek(OBJECT:([activerecord... |      1 |      2 |      1 | Clustered Index Seek | Clustered Index Seek | OBJECT:([activerecord_unittest].[dbo].[cars].[P... | [activerecord_unittest].[dbo].[cars].[id], [act... |          1.0 | 0.00312500004656613 | 0.000158099996042438 |        278 | 0.00328309996984899 | [activerecord_unittest].[dbo].[cars].[id], [act... | NULL     | PLAN_ROW | false    |                1.0 |
+----------------------------------------------------+--------+--------+--------+----------------------+----------------------+----------------------------------------------------+----------------------------------------------------+--------------+---------------------+----------------------+------------+---------------------+----------------------------------------------------+----------+----------+----------+--------------------+

You can configure a few options to your needs. First is the max column width for the logged table. The default value is 50 characters. You can change it like so.

ActiveRecord::ConnectionAdapters::SQLServer::Showplan::PrinterTable.max_column_width = 500

Another configuration is the showplan option. Some might find the XML format more useful. If you have Nokogiri installed, we will format the XML string. I will gladly accept pathches that make the XML printer more useful!

ActiveRecord::ConnectionAdapters::SQLServerAdapter.showplan_option = 'SHOWPLAN_XML'

NOTE: The method we utilize to make SHOWPLANs work is very brittle to complex SQL. There is no getting around this as we have to deconstruct an already prepared statement for the sp_executesql method. If you find that explain breaks your app, simple disable it. Do not open a github issue unless you have a patch. Please consult the Rails guides for more info.

New Rails Applications

When creating a new Rails application you need to perform the following steps to connect a Rails application to a SQL Server instance.

1. Create new Rails application, the database defaults to sqlite.

rails new my_app

2. Update the Gemfile to install the adapter instead of the SQLite adapter. Remove the sqlite3 gem from the Gemfile.

gem 'activerecord-sqlserver-adapter'

3. Connect the application to your SQL Server instance by editing the config/database.yml file with the username, password and host of your SQL Server instance.

Example:

development:
  adapter: sqlserver
  host: 'localhost'
  port: 1433
  database: my_app_development
  username: 'frank_castle'
  password: 'secret'

Installation

The adapter has no strict gem dependencies outside of ActiveRecord and TinyTDS.

gem 'activerecord-sqlserver-adapter'

Contributing

Please contribute to the project by submitting bug fixes and features. To make sure your fix/feature has a high chance of being added, please include tests in your pull request. To run the tests you will need to setup your development environment.

Setting Up Your Development Environment

To run the test suite you can use any of the following methods below. See RUNNING_UNIT_TESTS for more detailed information on running unit tests.

Dev Container CLI

With Docker and npm installed, you can run Dev Container CLI to utilize the .devcontainer configuration from the command line.

$ npm install -g @devcontainers/cli
$ cd activerecord-sqlserver-adapter
$ devcontainer up --workspace-folder .
$ devcontainer exec --workspace-folder . bash

From within the container, you can run the tests using the following command:

$ bundle install
$ bundle exec rake test

Note: The setup we use is based on the Rails Dev Container setup.

VirtualBox & Vagrant

The activerecord-sqlserver-adapter-dev-box is a Vagrant/VirtualBox virtual machine that has MS SQL Server installed. However, the activerecord-sqlserver-adapter-dev-box uses Vagrant and Virtual Box which will not work on Macs with Apple silicon.

Local Development

See the RUNNING_UNIT_TESTS file for the details of how to run the unit tests locally.

Community

There is a Gitter channel for the project where you are free to ask questions about the project.

Credits & Contributions

Many many people have contributed. If you do not see your name here and it should be let us know. Also, many thanks go out to those that have pledged financial contributions.

You can see an up-to-date list of contributors here: http://github.com/rails-sqlserver/activerecord-sqlserver-adapter/contributors

License

ActiveRecord SQL Server Adapter is released under the MIT License.