Check blocking sessions Let's create a scenario /* Create a blocking lock To begin, create a situation where one user is actively blocking another. Open two sessions. Issue the following commands in Session 1 to build the test table: */ SQL> create table tstlock (foo varchar2(1), bar varchar2(1)); --Table created. SQL> insert into tstlock values (1,'a'); --1 row created. SQL> insert into tstlock values (2, 'b'); --1 row created. SQL> select * from tstlock ; FOO BAR --- --- 1 a 2 b --2 rows selected. SQL> commit ; --Commit complete. --Now grab a lock on the whole table, still in Session 1: SQL> select * from tstlock for update ; --And in Session 2, try to update a row: SQL> update tstlock set bar= 2 'a' where bar='a' ; --This statement will hang, blocked by the lock that Session 1 is holding on the entire table. /*Identify the blocking session Orac...