should CREATE INDEX ON partitioned_table call PreventInTransactionBlock() ?

This blocks writes to all partitions until commit:

postgres=# begin; CREATE INDEX ON pt(i);
BEGIN
CREATE INDEX

Compare with CLUSTER rel1, rel2, ..., and REINDEX {SCHEMA|DATABASE|SYSTEM},
which release their locks as soon as each rel is processed.

I noticed while implementing REINDEX for partitioned tables, which, it seems
clear, should also avoid slowly accumulating more and more write locks across
an entire partition heirarchy.

--
Justin