Oracle Execution Plan Techniques - Quz

Each question is worth one point. Select the best answer or answers for each question.

1.	Which are valid tuning techniques for modern Web-based Oracle applications? Please select all the correct answers.
	A.	Avoid holding `SELECT FOR UPDATE` row locks across stateless web requests.
	B.	Place the web/application tier, such as ORDS or another application server layer, separately from the database tier when scalability and security require it.
	C.	Precompute, cache, or materialize expensive summary information that is frequently requested by web users.
	D.	Return only the rows and columns that the end user immediately needs.

2.	In a modern Oracle web application architecture, which platform layer normally contains the web listener or application gateway, such as Oracle REST Data Services? Please select the best answer.
	A.	The client platform
	B.	The application server or middle-tier platform
	C.	The database server platform

3.	Why should Web-based Oracle applications avoid holding `SELECT FOR UPDATE` locks across user think time or unreliable web connections? Please select all the correct answers.
	A.	A disconnected or abandoned web interaction can leave a database transaction open until the session is cleaned up.
	B.	Disconnected clients waste data buffer cache memory for the locked rows.
	C.	Long-lived transactions can hold unnecessary row locks and block other sessions.
	D.	Every disconnected browser automatically creates a runaway Oracle background process.