String concatenation - which is the fastest way ?

[SigmundV]

When I saw the headline I thought "oh no, not string concatenation
again... we have had scores of these thread before...", but this is a
rather interesting problem. The OP says he's not a database
developer,  but why is he then fiddling with internal database
operations? Wouldn't it be better to go back to the database
developers and have them look into parallel processing. I'm sure that
Oracle databases can do parallel processing by now...

Sigmund