Where I live the most popular way to anchor railings or fence into concrete is a method that I cannot find any reference about it on the web.
A 7mm hole is drilled into concrete and then a 8mm steel rebar without any coating is inserted into the hole with a hammer. Then the railing is welded on site with the rebar.This always works no failures.

The other less common way that is not preferred due to being hard to do and more expensive is with bolts with a flange.

Which way should I prefer for anchoring a long railing?