Detect row lock during insert

Question

Hello, is there a way to detect whether another process is inserting same row into same table, at the point of insert?
For eg
create table p1 ( col varchar2(10) );
alter table p1 add constraint p1_pk primary key (col);
Session 1:
Insert into p1 values ('1');
Session 2: (how to detect session 1 is inserting same row, before session 1 commits?)
Insert into p1 values('1');Message was edited by:
MWJ

Answer 1

You could test for a share lock:
SQL> lock table p1 in share mode nowait;
lock table p1 in share mode nowait
ERROR at line 1:
ORA-00054: resource busy and acquire with NOWAIT specified
SQL> You could catch this exception and do whatever you wanted to do.
But IMHO this is the wrong approach. For me the question is, why session 1 is allowed to wait (how long? forever?) until it commits. The application (i.e. the client, browser applet, <you name it>) should immediately commit. Why to do an insert and then a rollback? Then better do nothing.