Issue type:

[ ] question
[x] bug report
[ ] feature request
[ ] documentation issue

Database system/driver:

[ ] cordova
[ ] mongodb
[ ] mssql
[ ] mysql / mariadb
[x] oracle
[ ] postgres
[ ] cockroachdb
[ ] sqlite
[ ] sqljs
[ ] react-native
[ ] expo

TypeORM version:

[x] latest
[ ] @next
[ ] 0.x.x (or put your version here)

Steps to reproduce or a small repository showing the problem:

It's a copy of #693, cause the issue was closed, but the error still exists - at least with oracle.

When I'm using one of the getRepository(Entity).find({}) functions with realations array set in the FindOptions, I'm getting the too long identifier error. I think the main reason it doesn't work is because of Oracle, but I cannot be sure about it and I'm not able to change my db..

So it would be really cool, if anyone could make a PR, that allows the user to add an alias for RelationOptions or (the easier way) let the aliases only contain out of 1-2 letters.