Re: RE: performance when inserting into child tables

From: biti_rainy <biti_rainy_at_itpub.net>
Date: Thu, 22 Apr 2004 9:12:37 +0800
Message-Id: <20040422041301.80CBE72C841@turing.freelists.org>

hi,Mercadante, Thomas F

 exec dbms_system.set_ev(sid,serial#,10046,8,'') ;  trace the insert .

plz notice that , how many users do the inserting , which=  version for the oracle ,which tablespace ? LMT/ASSM ? if LMT and more than one user , freelists ?

if the child table has no index , the parent table changing may=  lock the child table

Best regards

yahoo id: feng_chunpei
A new dba from china

• from the mail-----
  >No - haven't tested it. I guess I wouldn't want to go changing=
  my
  >production system just on an Oracle class say-so.
  >
  >How would you test it? If it takes a lock and "quickly"=
  releases it, can we
  >see how long the lock was held for?
  >
  >Tom Mercadante
  >Oracle Certified Professional
  >
  >
  >-----Original Message-----
  >From: Jared.Still_at_radisys.com [mailto:Jared.Still_at_radisys.com]
  >Sent: Wednesday, April 21, 2004 2:38 PM
  >To: oracle-l_at_freelists.org
  >Subject: RE: performance when inserting into child tables
  >
  >
  >"The lack of indexes for the FK's will cause a share lock to be=
  taken
  >out on the child table when ever the parent is deleted or=
  updated."
  >The most recent Oracle class I took said that in 9i, this lock=
  on the
  >child
  >table is taken and released immediately. Supposedly to speed=
  the process
  >up
  >a bit.
  >
  >-----
  >
  >I did consider that this might have changed in 9i.
  >
  >The posted didn't mention a version, so I didn't pursue it.
  >
  >Have you tested to see if this is what happens in 9i?
  >
  >Jared
  >
  >
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Received on Wed Apr 21 2004 - 23:21:05 CDT