Support for SQL Server on Rails 5.x, 6.0, 6.1, and 7.0

[JesseChavez]

Hi All,

I have done some work to support the SQL Server / Azure SQL, it is mostly based on the sqlserver arel
visitor from the CRuby activerecord-sqlserver-adapter gem.

At the moment passes most of its tests and activerecord tests with few exceptions, the failing test are due
SQL server specific ways to do things such as:

• Average respects the data type columns so the avg of a integer column the result is integer
• A column has been specified more than once in the order by list throws an error, this kind of scenario
  gets ignored by Postgres.
• transaction isolation level repeatable_read and read_committed protect the read with a lock.
• SQL Server can't update identity keys
• etc.

NOTES:
To avoid the locking in read_committed we need to do:

"ALTER DATABASE [db_name] SET READ_COMMITTED_SNAPSHOT ON WITH ROLLBACK IMMEDIATE"

The activerecord tests run against my rails fork which contains specific fixes to run the test such as decimal max precision 38, quoting for SQL Server, etc. Please look at my commit in the rails fork.

https://github.com/JesseChavez/rails/tree/5-0-stable-dev

[rdubya]

@JesseChavez We've forked the activerecord-sqlserver-adapter codebase to create an activerecord-jdbcsqlserver-adapter. Can you take a look at it and see if it would work for your needs? It should make maintenance easier than with this approach and hopefully make it easier to also support 5.1, 5.2 and 6.0. You can see the changes to the forked code here: jruby/activerecord-jdbcsqlserver-adapter@5-0-stable...jruby:5-0-stable-jdbc and running that branch with the branch for my PR in this project currently passes most of the test suite for the sqlserver gem (which is their own tests plus the ActiveRecord tests). My current result is: 4913 runs, 14185 assertions, 11 failures, 5 errors, 6 skips and it looks like some of what you have been fixing may fix some of the remaining failures. Would you be willing to contribute towards that effort? The bulk of the failures are around timestamp accuracy and most of the skips are things that we can't/don't support.

[JesseChavez]

Just for reference if there is anyone still interested on an Active Record SQL Server adapter the works with JRuby

There is a fork of the activerecord-jdbc-adapter with Rails 5.0, 5.1, 5.2, 6.0. and 6.1 support:

https://rubygems.org/gems/activerecord-jdbc-alt-adapter

It is strongly advised to read the README file of the forked repository for more information and differences compared to activerecord-sqlserver-adapter or activerecord-jdbc-adapter adapters.

platforms :jruby do
  gem 'activerecord-jdbc-alt-adapter', '~> 61.0.0'
  gem 'jdbc-mssql', '~> 0.9.0'
end

Some of our apps are already running in production and one of them is a huge ancient finance Rails app originally created with Rails 2.0 and JRuby.