I was need similar feature for RDBMS and used class diagrams. IMO with simple conventions (like usage of protected and public fields of class diagram for PKs and indexes) it good enough for visualizing.
@startuml
class dummy {
Sample table.
==
#id int(10) -- A comment
field1 int(10)
.. Comment line, ignored ..
field2 varchar(128)
}
@enduml
Additionally for generating SQL DDL from PlantUML diagram sources I created simple Python script (for MySQL in my case) https://github.com/grafov/plantuml2mysql. It helpes me maintain real database with single source in format of class diagram. I think it may be easily adapted for other RDBMS as well.