RE: Update of Clobs *Performance*
- From: "Anthony Molinaro" <amolinaro@xxxxxxxx>
- To: <mschmitt@xxxxxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 3 Nov 2004 14:55:32 -0500
Mike,
when it comes to writes, the lob storage params are important.
Run your tests with the nologging as the storage params for the lobs.=20
The writes will be faster, potentially, much faster.
The reads will be slower as nologging =3D=3D nocache.
=20
- ant
-----Original Message-----
From: Mike Schmitt [mailto:mschmitt@xxxxxxxxxxxx]=20
Sent: Wednesday, November 03, 2004 2:29 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: Update of Clobs *Performance*
Hi all,
I have a developer who is trying to use PL/SQL to update all of the
CLOBS=20
of a specific table (nightly basis). I am looking for advice on how to=20
speed up the performance for this process. SQL tracing the process shows
the following before I cancel out.
call count cpu elapsed disk query current=20
rows
------- ------ -------- ---------- ---------- ----------=20
---------- ----------
Parse 1 0.00 0.00 0 0 0=20
0
Execute 19913 5116.93 5266.76 99893046 101038562 3=20
1
Fetch 0 0.00 0.00 0 0 0=20
0
------- ------ -------- ---------- ---------- ----------=20
---------- ----------
total 19914 5116.93 5266.76 99893046 101038562 3=20
1
Thanks
Table_A (141,000 rows, no indexes)
tabA_char VARCHAR2(10)
tabA_clob CLOB
Table_B (145,000 rows, no indexes)
tabB_num number
tabB_clob CLOB
Procedure
declare
v_clob varchar2(32500);
v_id varchar(10);
cursor cont_rep_clob is
select tabA_char, tabA_clob
from Table_A;
begin
open cont_rep_clob;
loop
fetch cont_rep_clob into v_id, v_clob;
exit when cont_rep_clob%NOTFOUND;
update Table_B
set tabB_clob =3D v_clob
where to_char(tabB_num) =3D v_id;
commit;
end loop;
close cont_rep_clob;
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