Free PGCES-02 Web TestEngine Demo

Q8 Single choice

Table "t1" is defined below.
Table "t1" has a column "id" of type INTEGER, and a column "name" of type TEXT. t1:
The following SQL is executed while client "A" is connected. BEGIN; SELECT * FROM t1 WHERE id = 2
FOR UPDATE; SELECT * FROM t1 WHERE id = 1 FOR UPDATE; -- (*)
While the second 'SELECT' statement, shown with (*), is being executed, a separate client "B" connects and executes the following SQL.
Select the correct statement about the execution results. UPDATE t1 SET name = 'turtle' WHERE id = 2;

Note: the default transaction isolation level is set to "read committed".

A
The update process for client "B" is blocked until the current connection for client "A" is finished.
B
The update process for client "B" is blocked until the current transaction for client "A" is finished.
C
The 'UPDATE' process for client "B" proceeds regardless of the condition of client "A".
D
The process of client "B" immediately generates an error.
E
The processes for both clients are blocked, and an error stating that a deadlock has been detected is generated.

PGCES-02 Web TestEngine demo