Saw error SP2-0547 when we tried to set the buffer size of server output in SQL*Plus.
SQL> set serveroutput on size 1000;
SP2-0547: size option 1000 out of range (2000 through 1000000)
As error message of SP2-0547 tells us, the buffer ranges from 2000 to 1000000, we should choose another value between 2000 and 1000000. For example, 20000 bytes.
SQL> set serveroutput on size 20000;
SIZE clause is optional, which accepts the default value if you ignore it. For 11g and earilier releases of SQL*Plus, the default value is 2000 bytes. On the other side, for newer releases of SQL*Plus, the default value is UNLIMITED.
Since PL/SQL statements use buffer to store the output, we can only see the final result after a successful or failed execution. That is to say, you see nothing during its execution, that is little disappointing.