vapor
Sort randomly
This is a pretty common database method…
return SomeTable(on: req).sort(.random).all()
return SomeTable(on: req).sort(.random).range(..<50)
I am told that this currently does not exist as the MySQL and PostgreSQL syntaxes are not exactly the same. That said, I think the importance of this is pretty high.
PSQL: select * from your_table ORDER BY random()
MySQL: select * from your_table ORDER BY rand()
I agree, we should add this. First, we will need to add something like SQLRandom() to https://github.com/vapor/sql-kit that calls on the SQLDialect to get the correct function name.
Note that LIMIT/range() queries will still scan the entire table in this case, as a random number needs to be generated for every single row before sorting. That can have unexpected performance implications.
Efficiently fetching a random subset of rows from Postgres is not that easy: https://stackoverflow.com/questions/8674718/best-way-to-select-random-rows-postgresql
