I've an Index TBS with 5 x 100Mb datafiles.

Over the past year i've regularly rebuilt indexes as and when they've extended and I'm now in the position where each datafile is c. 80% full. (I presume this is because of the regular rebuilds)

Could I

(a) REBUILD the indexes to a separate temporary tablespace with 1 500 Mb datafile.
(b) Coalesce my existing,now empty, original index tablespace.
(c) Drop 1 of my 5 index datafiles.
(d) REBUILD the undexes back into the newley coalesced TBS with 4 x 100 Mb datafiles.

?