[sqllab] Add configuration option to disable data preview query in SQL editor

[akedrou]

Is your feature request related to a problem? Please describe.
We are using Superset with Trino over very wide tables with complex nested data columns. When writing queries in SQL editor, getTableMetadata will automatically dispatch a data preview query that can lock up the UI for a few seconds when it renders the results.

Describe the solution you'd like
I would like a configuration option to disable the data preview query. This setting could be global, but I think it makes most sense as a database extra configuration option sql_editor_preview_data (default to current behavior/True) that is returned in the get_table_metadata API response as previewData. If False, the query would be skipped.

Describe alternatives you've considered

• Improving the performance of the response rendering (e.g. limiting the number of columns; ensuring the UI doesn't lock)
  • Limiting the number of columns defeats the purpose of a preview query.
  • Showing all the columns in such a wide table is not an effective preview anyway.
• Placing the setting at a table/schema level
  • Would be nice to enable previews as much as possible, and this could be managed by table with something like a dictionary of table->bool
  • The benefit doesn't seem worth the cost of a confusing database setting.

Additional context
I'm happy to submit a PR for the feature assuming the proposed solution (or something similarly straightforward) works.

[junlincc]

i agree, we currently send out a preview query each time when selecting a table... it can be cumbersome for data warehouse like clickhouse with maaaaany columns. please do open a PR. :) thanks for suggesting

cc @betodealmeida @eschutho

[eschutho]

@yousoph

[akedrou]

Hi @junlincc - I opened a PR for this change a few weeks back (#14768). Sorry it took a bit to follow up, but is there some other step I need to follow before tests are approved to run on it and it gets reviewed or is it just waiting on someone to have some time? I checked the guide for contributing but it's entirely possible I missed something. Thanks!