Transportable Tablespaces and READ ONLY in Oracle Database 12c

We recently worked with a customer who noticed that they were not able to use transportable tablespaces to connect the same tablespace data files to two databases at the same time, even after setting the tablespaces READ ONLY in SQL*Plus. This is new behavior in 12c, and many customers are not yet aware of this change. Here are the details of what changed, why, and how you might want to deal with it if the changes affect your environment. What Changed? Starting in 12.1, data pump sets tablespaces read write during the import phase of a transportable tablespace migration. This…