For each member being rendered on
Projects::ProjectMembersController#index, there was a query to the users
table to retrieve the corresponding user:
```
SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1
```
Realized window functions are not available in older MySQL versions
either.
Falling back to DISTINCT ON for postgresql and a convoluted translation
for MySQL.
Andreas Brandl