Schema Refresh Fails for Certain Datasource Types

[snickerjp]

Problem Description

Schema refresh execution for certain datasource types (results, python, etc.) causes NotSupported exceptions, generating error logs and metrics.

Steps to Reproduce

1. Create a datasource of type Query Results or Python
2. Wait for the scheduler to execute schema refresh (default 30-minute interval)
3. Check worker logs

How to check logs:

# For Docker Compose
docker compose logs -f worker

# Or manually execute schema refresh
docker compose exec worker python -c "
from redash import create_app
from redash.tasks.queries.maintenance import refresh_schemas
app = create_app()
with app.app_context():
    refresh_schemas()
"

Actual Behavior (Error Logs)

[WARNING] Failed refreshing schema for the data source: Query Results
Traceback (most recent call last):
  File "/app/redash/tasks/queries/maintenance.py", line 166, in refresh_schema
    ds.get_schema(refresh=True)
  File "/app/redash/models/__init__.py", line 217, in get_schema
    schema = query_runner.get_schema(get_stats=refresh)
  File "/app/redash/query_runner/__init__.py", line 232, in get_schema
    raise NotSupported()
redash.query_runner.NotSupported
[INFO] task=refresh_schema state=failed ds_id=1 runtime=0.00

[WARNING] Failed refreshing schema for the data source: python
Traceback (most recent call last):
  ...
redash.query_runner.NotSupported
[INFO] task=refresh_schema state=failed ds_id=2 runtime=0.00

Expected Behavior

These datasource types don't have the concept of schema, so they should be excluded from the schema refresh process. Error logs and metrics should not be recorded.

Impact

• Unnecessary error logs are recorded in large quantities
• refresh_schema.error metrics become inaccurate
• Log readability decreases
• Potential wasteful endpoint access

Environment

• Redash Version: 25.11.0-dev (master branch)
• Affected datasource types:
  • results (Query Results)
  • python (Python)
  • Other types that don't implement get_schema method

Proposed Solution

Allow specifying datasource types to exclude from schema refresh via environment variable:

REDASH_SCHEMAS_REFRESH_EXCLUDED_TYPES=results,python

By excluding results and python by default, the issue will be automatically resolved in existing environments.