Re: what is the fastest way to update a big table with more than 50000 rows and 20 columns

Try this:

update cs c1 set c1.source = (

    select j.source
    from join j, cs c
    where trim(j.totid)=trim(c.totid)

       and j.source is not null)
    where trim(c1.totid)=trim(c.totid);

Should be faster, at least because you don't have to switch between PL/SQL and SQL.
Also, do you really have to use trim()?
I guess, 'TITID' is char type. Why not make it varchar2? In this case, you will not have to use trim(). Using function prevents from using indexes on both tables, so most probably you are doing table scans.

Igor Neyman, OCP DBA
ineyman_at_perceptron.com

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Wednesday, October 31, 2001 7:15 AM rows and 20 columns

> hi guys,
> i have a big problem in updating an oracle 8i 1.7 database table
with
> more than 50000 rows and 20 columns. The problem is: i have another table
> with approximately 17000 rows and 12 columns. The latter one holds newer
> data, and most of them have the same primary key as the previous one
> (16000). Now, i want to update the older table with newer data from the
new
> table. I wrote a pl/sql procedure to achieve this task, but it takes too
> long ( nearly 12 hours) ,
> can you have a look at the below procedure and tell me what is wrong
> with it and where i am making mistake? CAn you suggest me a faster and
more
> efficient way to do that?
> thanks alot for your help in advance.
> cheers :)
> my Pl/sql procedure :
> ********************
> declare
> cursor c1 is
> select c.totid,j.source from join j,cs c where j.source is not null
> and trim(j.totid)=trim(c.totid);
> --join is the new table (17700 rows)
> --cs id the older one (50300rows)
> tot cs.TOTID%type;--totid is the primary key for both tables
> src cs.source%type;--source is the column to be updated
> begin
> open c1;
> loop
> fetch c1 into tot,src;
> tot:=trim(tot);
> exit when c1%notfound;
> update cs set source=src where trim(totid)=tot;
> end loop;
> commit;
> close c1;
> end;
>
>
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> Author: yilmaz
> INET: yilmaz_at_hwajet.com.tw
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Igor Neyman
  INET: ineyman_at_perceptron.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
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