Support for MSSQL

[faustinoaq]

Hi, currently, MSSQL is available on Linux and is pretty easy to use via docker.

I found nothing related to how connect Crystal to Microsoft SQL Server.

Is possible to create an adapter for MSSQL?

[bcardiff]

There is no current option for mssql.
A driver would need to either:

1. implement binding to http://www.freetds.org/ (https://github.com/rails-sqlserver/tiny_tds might serve for inspiration), or

2. implement the https://msdn.microsoft.com/en-us/library/dd304523.aspx protocol directly to the socket as crystal-pg and crystal-mysql

[Virtual-Machine]

This is literally the only thing holding me back from using Crystal in production at work. I have several legacy databases I need to support that are in MSSQL. Lacking the MSSQL driver is forcing me to use Golang which is ok but I would definitely prefer to be using Crystal. Especially when it comes to the database api, I think Crystal offers much nicer syntax compared to Go.

I looked into pulling fresh nightly copies of data from MSSQL to MYSQL but inevitably someone complains about stale data and its too costly to be pulling the full set more frequently during the day. I am no expert but could I possibly link the MSSQL and MYSQL databases and then query out the MSSQL data through MYSQL or do linked servers not function the way I am expecting?

[faustinoaq]

Crystal on Windows is in progress, so, I think a MSSQL binding would be useful, I will try to do something. 😄 (I hope keep my smile)

@fridgerator Did you try to create a MSSQL binding before? how was that?

[fridgerator]

@faustinoaq No I never tried to do it in crystal. I recently had to connect a rails app to a legacy MSSQL server, and used tiny_tds (mentioned above). It was an unpleasant experience.

[wonderix]

Implementing a binding to freetds will not work, because a call to the library will block all fibers in crystal. The ruby binding is using rb_thread_call_without_gvl to release the global interpreter lock. This will not be possible in crystal.
The only possibility would be to implement the protocol directly. Perhaps jtds could be a starting point.

[bcardiff]

Even though I would encourage a protocol implementation directly, I'm not convinced that freetds can't be wrapped.

It is possible to have a dedicated thread to handle the calls to the library if that is needed by freetds. I did something like that in https://github.com/bcardiff/crystal-fswatch. I am not familiar with freetds though.

[wonderix]

I started with an implementation of tds in plain crystal