Undesired sys statement on insert

From: Domenico Vasile <domenico_vasile_at_libero.it>
Date: Mon, 29 Jul 2002 18:24:45 +0200
Message-ID: <MPG.17af8ab6677a15698969a@130.133.1.4>

Hi all. Below is a sketch from a tkprof output file:

select c.name, u.name
from
con$ c, cdef$ cd, user$ u where c.con# = cd.con# and cd.enabled = :1 and
c.owner# = u.user#

call count cpu elapsed disk query current rows
------- ------ -------- ---------- ---------- ---------- ----------

Parse 5743 1.84 2.17 0 0 0 0
Execute 5743 6.03 5.64 0 0 0 0
Fetch 5743 10.89 11.44 10 51687 17229 5743
------- ------ -------- ---------- ---------- ---------- ----------

total 17229 18.76 19.25 10 51687 17229 5743

Misses in library cache during parse: 1
Optimizer goal: CHOOSE
Parsing user id: SYS (recursive depth: 2)

Rows Row Source Operation

-------  ---------------------------------------------------
      1  NESTED LOOPS 
      1   HASH JOIN 
      1    TABLE ACCESS BY INDEX ROWID CDEF$ 
      2     INDEX RANGE SCAN (object id 48)
   1381    TABLE ACCESS FULL CON$ 
      1   TABLE ACCESS CLUSTER USER$ 
      1    INDEX UNIQUE SCAN (object id 11)



************************************************************************

I get this during an insert of 5743 rows. It seems that for each rows inserted in the actual INSERT statement the previous select is automatically issued. Why does the statement require such an heavy parsing? Furthermore I have no constraint defined on my table. Why is the statement required at all? Is there a way to avoid (or to "smooth") the sys statement?
TIA
--Domenico Received on Mon Jul 29 2002 - 11:24:45 CDT