How to save a PDB open state in Oracle Multitenant

Preserve a PDB open state so it returns to that mode after a CDB restart, instead of staying mounted.

This changes startup behaviour for the PDB. Run it from the root while the PDB is in the mode you want remembered.

-- Remember the current open mode
ALTER PLUGGABLE DATABASE &&pdb_name SAVE STATE;

-- Stop remembering:
-- ALTER PLUGGABLE DATABASE &pdb_name DISCARD STATE;

-- Verify (read-only)
SELECT con_name, state
FROM   dba_pdb_saved_states
WHERE  con_name = UPPER('&pdb_name');