Postgrex without Array types?

[Nick Pavlica]

All,

  I'm trying to use Elixir with CockroachDB (https://github.com/cockroachdb/cockroach).  They are implementing the Postgresql protocol for their SQL interface, but haven't implemented the Array type.  There is a ticket open for adding arrays, but they haven't had a chance to implement it yet.  I've been trying to connect with Postgrex, but get the following error:

11:28:55.749 [error] Postgrex.Protocol (#PID<0.157.0>) failed to connect: ** (Postgrex.Error) ERROR (internal_error): syntax error at or near "("

SELECT t.oid, t.typname, t.typsend, t.typreceive, t.typoutput, t.typinput,

       t.typelem, coalesce(r.rngsubtype, 0), ARRAY (

                                                   ^

Is it possible to connect without calling for an ARRAY type?  They have several Postgresql drivers working, so I know that it can be done :)  I've been looking at the Postgrex source, but haven't found a solution yet.  Your guidance is appreciated!

Thanks!

--Nick  

[José Valim]

Hi Nick!

Postgrex does a query to get all of the database types once it connects. Maybe you can try rewriting the query yourself in a way it doesn't use ARRAY? You may need to slightly change the code after too but you should definitely give it a try. :)

José Valim

www.plataformatec.com.br

Skype: jv.ptec

Founder and Director of R&D

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[Nick Pavlica]

Jose,

   

Postgrex does a query to get all of the database types once it connects. Maybe you can try rewriting the query yourself in a way it doesn't use ARRAY? You may need to slightly change the code after too but you should definitely give it a try. :)

This gave me a great place to start investigating.  While trying to rewrite the query in lib/postgrex/types.ex, I discovered that there are features other than ARRAY that haven't yet been implemented in CockroachDB.  I posted my questions to the CockroachDB group, and got this response: (https://groups.google.com/forum/#!topic/cockroach-db/WVm4P8PX1cM).  Essentially stating that they don't have any meta data tables, but do plan to support information_schema in the near term.  At the moment, they are using a static map (https://github.com/cockroachdb/cockroach/blob/master/sql/pgwire/types.go#L362) of all the available types.  If I understand  the Postgrex code properly, it builds the type map dynamically in types.ex.  I'm guessing that I would need to modify types.ex so that it would use the static type map that CockroachDB uses.  That being said, is there a way to add this functionality/behavior to Postgrex, without having to create a whole new thing, like PostgrexCDB?  

Thanks!

-- Nick

[José Valim]

You should open up an issue in Postgrex. Maybe we can allow a types configuration that you would set in the format that Postgrex expects and, when this configuration is available, Postgrex would no longer perform the query.

José Valim

www.plataformatec.com.br

Skype: jv.ptec

Founder and Director of R&D