Hi Michael,
> so I'd wonder about just returning an error first
Agreed. The only case that fails is two or more of the named indexes
sharing a table with -j >= 2 (they batch into one multi-statement query).
And for that case --jobs cannot parallelize anyway: the indexes of one
table have to be reindexed one at a time to avoid deadlocks. So fixing the
parallel path unlocks no speed, it only removes the error. Erroring out
looks right to me; a clear message would beat today's "cannot run inside a
transaction block". Happy to write that.
Regards,
Manu