Changed 
One of the things I keep in mind when naming threads is asking myself what somebody might search for in a search engine for that topic, and usually people will search for things like “Elixir Postgres driver” or “Elixir Oracle adapter” 
but Ecto Oracle adapter is cool too if you’d prefer that 
I’m sure you’ll get there 
I got DBConnection.prepare_execute working (yay ) which is fetch everything untill end of table.
Next step is to do the cursor, i.e. fetch in batches. I implemneted handle_declare/4 and handle_fetch/4 functions. Now I am stuck trying to invoke them! As per my undertsanding above I should call prepare_stream/4, but unlike prepare_execute/4 the first argument of prepare_stream/4 is t() (%DBConnection{}) and not GenServer.server(). DBConnection.start_link only gives back a {:ok, pid()} (which seems to be same as GenServer.server()).
How do I get a t() from DBConnection.start_link?
TIA
Streaming must happen inside a transaction, see: DBConnection.transaction/3. The fun passed to transaction/3 gets the t().
Here is the first working version (very much alpha) of the driver GitHub - KonnexionsGmbH/OraLixir: Oracle driver for Elixir · GitHub
This is still work-in-progress. Not all DBConnection callbacls are (correctly)implemented.
But connect and query is possible.
iex> {:ok, pid} = OraLixir.start_link([])
{:ok, #PID<0.69.0>}
iex> OraLixir.prepare_execute(pid, "name", "SELECT 'string', 1, sysdate FROM DUAL", [], [])
{:ok, %OraLixir.Query{}, %OraLixir.Result{}}
I will very much appreciate any comment / verification / feedback / code review and general guidence etc for me to improve on this.
TIA
Hi all,
An update on development progress and current status of OraLixir : An Ecto Adapter for Oracle
OraLixir.Connection use DBConnection tests are now passing in Travis
==> oralixir
Compiling 5 files (.ex)
warning: function message/1 required by behaviour Exception is not implemented (in module OraLixir.Error)
lib/oralixir/error.ex:1: OraLixir.Error (module)
Generated oralixir app
.Table OraLixir_test dropped if existed
Table OraLixir_test created : CREATE TABLE OraLixir_test (COL1 NUMBER, COL2 VARCHAR2(1000))
First row inserted to OraLixir_test : INSERT INTO OraLixir_test (COL1, COL2) VALUES(1, 'one')
Second row inserted to OraLixir_test : INSERT INTO OraLixir_test (COL1, COL2) VALUES(2, 'two')
All rows selected from OraLixir_test : SELECT * FROM OraLixir_test
Updated one row in OraLixir_test : UPDATE OraLixir_test SET COL1=3, COL2='three' WHERE COL1=2
All rows selected from OraLixir_test (including updated) : SELECT * FROM OraLixir_test
truncated all rows from OraLixir_test : UPDATE OraLixir_test SET COL1=3, COL2='three' WHERE COL1=2
No rows selected from OraLixir_test (after truncate) : SELECT * FROM OraLixir_test
The mix tests will also serve as interface documentation if anyone already would like to try it out at Connection interface level.
Thanks a lot @Cruz for all your help in testing and improvement advices.
I will very much appreciate if I get some code/design review on what I have so far.
Currently working / learning on how get into Ecto.Adapters.SQL implementation for OraLixir.
In jamdb_oracle prepare_stream/4 is not declared at all, only stream/4 and handle_fetch/3 are implemented.