Sylvain Lebresne

I know this was approved before, but needed to make a few changes for the sake of the cndb, so re-requested review to have a look on the last changes...

I don't have tons of context on riptano/cndb#7146 to go with, but I'm not sure this is doing what we want. Afaict, as is, the patch just parallelize the creation...

> I don't think we can predict it in advance "predict" might have been the wrong word here. What I was refering to is the fact that an sstable iterator...

> This worked in Fed1 because the query planner had no problem sending requests to this nodes subgraph that included types it didn't define. This seemed sensible because the queries...