query plan hint support

[bradzacher]

It'd be good if you could add the ability to do things like mysql's FORCE INDEX / mariadb's USE INDEX hints.

There are some situations when the DB's optimiser sucks and needs a little help for a particular join.

For example, I've got a join whose conditions are well indexed, but mysql decides to ignore the index. If I wasn't using join-monster, I could rectify this issue (and reduce the query time by a factor of 5) by adding FORCE INDEX (xxx) after the table name in the join.

I know postgres doesn't have it, but something like a prefix/postfix option for joins would be good so that there is general support for doing things like this.

IIRC oracle can do this via comments in the select. This might be possible via the alwaysFetch option.