Show Presto views as views, not tables

[betodealmeida]

CATEGORY

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• Bug Fix
• Enhancement (new features, refinement)
• Refactor
• Add tests
• Build / Development Environment
• Documentation

SUMMARY

Currently, Presto displays views as tables, since the statement SHOW TABLES shows both views and tables, and there's no SHOW VIEWS.

One workaround to get the list of views is to query the information_schema schema:

SELECT table_name FROM information_schema_views WHERE table_schema='default';

This returns the actual list of views, but it's slow. On our Presto cluster it takes approximately 90 seconds to get all the views across all schemas. Fortunately, the API that exposes the views is cached, so this shouldn't be too bad.

I added a new feature flag, PRESTO_SPLIT_VIEWS_FROM_TABLES (open for better name suggestions), that when enabled will show views differently than tables in SQL Lab.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

Now views are properly marked as such in Presto:

ADDITIONAL INFORMATION

• Has associated issue:
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

REVIEWERS

@khtruong @etr2460

[codecov-io]

Codecov Report

Merging #8243 into master will decrease coverage by 0.04%.
The diff coverage is 42.1%.

@@            Coverage Diff             @@
##           master    #8243      +/-   ##
==========================================
- Coverage   65.72%   65.68%   -0.05%     
==========================================
  Files         481      481              
  Lines       23317    23348      +31     
  Branches     2572     2572              
==========================================
+ Hits        15326    15335       +9     
- Misses       7853     7875      +22     
  Partials      138      138

Impacted Files	Coverage Δ
superset/assets/src/components/TableSelector.jsx	77.69% <ø> (ø)	⬆️
superset/models/core.py	81.93% <ø> (ø)	⬆️
superset/views/core.py	70.36% <0%> (-0.05%)	⬇️
superset/db_engine_specs/presto.py	70.26% <28%> (-2.12%)	⬇️
superset/db_engine_specs/postgres.py	93.54% <66.66%> (-3.01%)	⬇️
superset/db_engine_specs/sqlite.py	70.96% <75%> (-1.45%)	⬇️
superset/db_engine_specs/base.py	85.38% <80%> (-0.24%)	⬇️
superset/connectors/druid/models.py	81.71% <0%> (+0.04%)	⬆️

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