Add dataset does not work for Exasol backend when using pydobc based sqlalchemy dialect

[Nicoretti]

Add dataset does not work for Exasol DB when using pydobc based sqlalchemy dialect.
(see also exasol/sqlalchemy-exasol#136)

How to reproduce the bug

0. Setup Exasol DB and add it as data source

1. Go to 'Datasets'

2. Click on '+ DATASET'

3. Select the Exasol DB as database

4. Select a schema containing views and tables

5. Try to select a Table/Schema

6. No Tables/Schemas are shown

Expected results

Table(s) and view(s) of the specified schema are shown.

Actual results

No table(s) nor view(s) of the specified schema are shown.

Screenshots

Expected result:

Actual result

Log

2022-05-18 09:49:43,443:INFO:werkzeug: * Running on http://127.0.0.1:8000/ (Press CTRL+C to quit)
2022-05-18 09:49:46,313:INFO:werkzeug:127.0.0.1 - - [18/May/2022 09:49:46] "GET /api/v1/me/ HTTP/1.1" 200 -
2022-05-18 09:49:48,206:INFO:werkzeug:127.0.0.1 - - [18/May/2022 09:49:48] "GET /api/v1/database/?q=(filters:!((col:database_name,opr:ct,value:%27%27)),order_columns:database_name,order_direction:asc,page:0,page_size:100) HTTP/1.1" 200 -
2022-05-18 09:49:49,715:INFO:werkzeug:127.0.0.1 - - [18/May/2022 09:49:49] "GET /api/v1/database/?q=(filters:!((col:database_name,opr:ct,value:%27%27)),order_columns:database_name,order_direction:asc,page:0,page_size:100) HTTP/1.1" 200 -
2022-05-18 09:49:49,805:INFO:werkzeug:127.0.0.1 - - [18/May/2022 09:49:49] "GET /api/v1/database/1/schemas/?q=(force:!f) HTTP/1.1" 200 -
Attempt to use a closed connection.
2022-05-18 09:49:52,059:WARNING:superset.models.core:Attempt to use a closed connection.
Attempt to use a closed connection.
2022-05-18 09:49:52,112:WARNING:superset.models.core:Attempt to use a closed connection.
2022-05-18 09:49:52,125:INFO:werkzeug:127.0.0.1 - - [18/May/2022 09:49:52] "GET /superset/tables/1/test_get_metadata_functions_schema/undefined/false/ HTTP/1.1" 200 -

Environment

• browser type and version: Firefox 100.0
• superset version: superset version = 1.5.0
• python version: python --version = 3.9.7
• node.js version: node -v == -
• any feature flags active: exasol

Checklist

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven't found one similar.

Additional context

This issue was discovered within the context of another issue (#16541). The reporter of that issue mentions that only the versionsqlalchemy-exasol 2.0.10 is working properly together with superset.

We already have investigated this issue and can confirm that the cause of this issue is a bug in the exasol sqlalchemy dialect. For further details on the bug in the exasol dialect see also sqlalchemy-exasol#issue-136.

A fix for the sqlalchemy-exasol issue is on the way, see this PR.

Once the PR is merged and a new version of sqlalchemy-exasol have been released, adjusting the version constrains of sqlalchemy-exasol within superset will fix this bug.