Drop and recreate -- if you created the MV on a prebuilt table then you'll be able to keep the current data set. Otherwise, if you need the current data set then copy it to a new table, drop the MV, rename the new table back to the MV name and create the MV with the new query ON PREBUILT TABLE.
How to modify the query of a materialized view?
Do we need to drop and recreate the mview ?
Or is there any ALTER statement to do this without dropping and recreating?
Thanks in advance, Anurag