Behavior of read-only databases Complete the statement: Read-only databases are ________ updated (consider the operational meaning of read-only).

Introduction / Context:
Some environments require data to be immutable for safety, auditing, or performance reasons. A read-only database enforces this by preventing changes to its contents at the database level.

Given Data / Assumptions:

• “Read-only” is an explicit operational mode or configuration.
• Users and applications can connect and run SELECT statements.
• Any attempt to modify data should fail by design.

Concept / Approach:

By definition, a read-only database disallows DML changes such as INSERT, UPDATE, DELETE, and MERGE, as well as most DDL that would alter stored data. It may be used for reporting, replication targets, or archival snapshots where integrity and repeatability are paramount.

Step-by-Step Solution:

Verification / Alternative check:

Vendor documentation (e.g., setting a database or tablespace to read-only) states that write operations fail until the database is returned to read-write mode.

Why Other Options Are Wrong:

• Always/commonly/seldom: contradict the strict definition of read-only.
• “Periodically by triggers only”: triggers execute on writes; if writes are disallowed, triggers cannot change stored data.

Common Pitfalls:

• Assuming read-only allows temporary table writes; configurations vary, but the core database contents remain unmodifiable.
• Confusing read-only replicas (which receive changes via replication) with local user-initiated updates; replicas apply changes internally but still reject client writes.

Final Answer:

never