[welcome page][perf] Slow queries to generate welcome page

How to reproduce the bug

1. As user using Superset for years,
2. Go to https://superset.d.musta.ch/superset/welcome/
3. Welcome page show spinner very, very long time:
4. from MySQL Slow query log, I can see the query to get recent viewed items can take > 20 mins.

Environment

airbnb production

• superset version: superset version: latest master

Checklist

Make sure to follow these steps before submitting your issue - thank you!

• 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

Add any other context about the problem here.

[cesar-loadsmart]

We’ve fixed our problem by creating a specific index for this query:

SELECT anon_1.dashboard_id AS anon_1_dashboard_id, anon_1.slice_id AS anon_1_slice_id, anon_1.action AS anon_1_action, anon_1.dttm AS anon_1_dttm, dashboards.slug AS dashboard_slug, dashboards.dashboard_title AS dashboards_dashboard_title, slices.slice_name AS slices_slice_name 
FROM (SELECT logs.dashboard_id AS dashboard_id, logs.slice_id AS slice_id, logs.action AS action, max(logs.dttm) AS dttm 
FROM logs 
WHERE logs.action IN ('explore', 'dashboard') AND logs.user_id = <USERID> AND logs.dttm > '2021-08-24T17:20:50.496891'::timestamp AND (logs.dashboard_id IS NOT NULL OR logs.slice_id IS NOT NULL) GROUP BY logs.dashboard_id, logs.slice_id, logs.action) AS anon_1 LEFT OUTER JOIN dashboards ON dashboards.id = anon_1.dashboard_id LEFT OUTER JOIN slices ON slices.id = anon_1.slice_id 
WHERE dashboards.dashboard_title != '' OR slices.slice_name != '' ORDER BY anon_1.dttm DESC 
 LIMIT 6

Our Superset became faster than it was released, today we have around 400 users and more than 100 published dashboards.

[jplanckeel]

Hello, we have created a purge for the log but it is slow because the logs table is constantly called. This has been fixed by creating an index on the dttm column of the logs table.

Can we add an index on next release ?

our PR for add purge on event logger 😉 https://github.com/apache/superset/pull/20636

CREATE INDEX "dttm_index"
ON "logs" ("dttm");