Added initial Teradata JDBC driver implementation

[ofir-insait]

This patch introduces initial Teradata JDBC driver implementation.

Introducing the following env vars:
CUBEJS_DB_TERADATA_NAME - optional, name of the database to connect to CUBEJS_DB_TERADATA_URL - mandatory, e.g.
jdbc:teradata://<teradata_db_ip>/USER=<teradata_user>,PASSWORD=<teradata_user_pwd>
CUBEJS_DB_TERADATA_ACCEPT_POLICY - optional, true/false to accept terms and conditions

As part of the Docker build we fetch an external dependency, namely the Teradata JDBC jar file into:
/cubejs/packages/cubejs-teradata-jdbc-driver/download/terajdbc4.jar

More information on setting up a server and using this driver is documented here:
packages/cubejs-teradata-jdbc-driver/README.md
We tested it with an on-prem Teradata server as well as Teradata Express.
Known limitations include:

1. Max 15 transactions per cursor
   https://docs.teradata.com/r/GVKfXcemJFkTJh_89R34UQ/YB_t1rB9boiHUNbSQlvLRA (Error 3130).

2. Cursor limitations
   After 15 transactions we get the 3130 error from the cursor.
   Temporary workaround: doing a Cube pre-processing step where we manually
   generate the schemas outside of Cube using Teradata SQL CLI client (bteq).

3. Only handling table views
   Handling tables (in addition to table views)
   Currently we only support table views (tableKind=‘V’) and not tables.
   Need to implement and test it.

Check List

• Tests has been run in packages where changes made if available
• Linter has been run for changed code
• Tests for the changes have been added if not covered yet
• Docs have been added / updated if required

Issue Reference this PR resolves

[For example #12]

Description of Changes Made (if issue reference is not provided)

[Description goes here]

[ofir-insait]

In order to test this patch with Cube you can setup a Teradata Express (Vantage) server on Azure VM (for example) using this guide:
https://quickstarts.teradata.com/run-vantage-express-on-microsoft-azure.html

You can also setup a local Teradata instance using VirtualBox on x86:
https://quickstarts.teradata.com/getting.started.vbox.html

[paco-valdez]

@ofir-insait I'm not familiar with DB Drivers, so I can't do a full review, but my 2 cents are that drivers usually don't have their own env variable to define DB name:
Exhibit A
Exhibit B
Exhibit C

[paco-valdez]

@ofir-insait Also, can you provide some insight as to why only Views are supported?

[ofir-insait]

The main reason is time, this is what our clients used and what we needed to support.
We have actually started with schema discovery for tables as well and the delta is not huge to add this support.
Teradata obviously has metadata for tables as well.

Note that this is also stated in the commit message:

Only handling table views
Handling tables (in addition to table views)
Currently we only support table views (tableKind=‘V’) and not tables.
Need to implement and test it.

[ofir-insait]

@ofir-insait I'm not familiar with DB Drivers, so I can't do a full review, but my 2 cents are that drivers usually don't have their own env variable to define DB name: Exhibit A Exhibit B Exhibit C

Hey @pacofvf this is partially true, if you look at DataBricks for example, you would find several db specific env vars.
As was advised on Slack, we used DataBricks as a baseline for contributing this patch.

What we could do, though, is:

1. Use CUBEJS_DB_NAME instead of CUBEJS_DB_TERADATA_NAME
2. Remove CUBEJS_DB_TERADATA_ACCEPT_POLICY and set it to hard coded true

But we would still need CUBEJS_DB_TERADATA_URL IMHO.

[paveltiunov]

@ofir-insait Thanks a lot for contributing! An E2E test for Teradata would be very much appreciated. You can use this one as an example: https://github.com/cube-js/cube.js/blob/master/packages/cubejs-testing/test/smoke-materialize.test.ts.

[paveltiunov]

@ofir-insait While you're working on a test, you might want to consider publishing your driver version as is and adding a backlink in our docs. Please see https://github.com/cube-js/cube.js/blob/master/CONTRIBUTING.md#contributing-database-drivers.