Step 1
How did I reduce my Sentry database's size?
Use sentry cleanup --days 0 on the Step 3.

Step 2
The Step 1 does not clean sentry_eventuser for an unknown reason:

So I clean it explicitly:
DELETE FROM sentry_eventuser;
VACUUM FULL;
How did I reduce my Sentry database's size?
Use sentry cleanup --days 0 on the Step 3.

The Step 1 does not clean sentry_eventuser for an unknown reason:

So I clean it explicitly:
DELETE FROM sentry_eventuser;
VACUUM FULL;