B). CREATE INDEX price_idx on products (price); E. ALTER TABLE products DROP UNUSED COLUMNS; F. DROP TABLE products.
Comprehensive and Detailed Explanation WITH all References:
When a table is in read-only mode, most types of modifications are prohibited. However, certain operations can still be performed.
A). Incorrect. You cannot drop a column from a table that is in read-only mode, as it is a modifying operation.
B). Correct. You can create an index on a read-only table. Creating an index does not modify the actual rows within the table; it builds a separate structure used for faster access. C. Incorrect. The SET UNUSED statement marks one or more columns as unused so they can be dropped when the database is not busy. This operation is considered a modifying operation and therefore is not allowed on a read-only table. D. Incorrect.
Truncate is a DDL operation that would delete all rows from a table. This operation is not allowed on a read-only table. E. Correct. The ALTER TABLE ... DROP UNUSED COLUMNS statement is used to drop columns that have been previously marked as unused using the SET UNUSED statement. This operation is allowed because it only affects previously marked unused columns, not actively used data. F. Correct.
Dropping a table is allowed even if it's in read-only mode because it is a DDL operation that does not operate on the rows of the table but rather on the object itself.
The behavior of read-only tables and the operations that can be performed on them are detailed in the Oracle Database SQL Language Reference and Oracle Database Administrator's Guide.