Investigate which other (if any) db.Migrator methods need to be implemented

[etiennedi]

Background

It is impossible to tell at the moment which methods in the interface that db.Migrator tries to implement actually need to contain an implementation. It seems some of them are also not implemented in esvector. Others are stubbed out in esvector (just returning nil, but no error).

Goals

• find out if any of the currently not-implemented methods are actually required
• if yes, create issues for the missing methods
• if no, delete the missing methods from the interface and cleanup in the associated usecase.

[etiennedi]

cc @laura-ham This is related to what we talked about yesterday: You mentioned schema-related API methods that possibly still exist and can't be used. This issue has the same underlying problem - only that its affect are the respective methods on the standalone and es packages.

Either way we should clean this up as part of either the v0.23.0 or the v1.0.0 release.