Re: Which is more efficient For vs FORALL

Rick_Cale_at_teamhealth.com wrote:
>
> Hi DBAs
>
> Here are 2 scenario's. Which one is more efficient?
> Assume 10,000 records to update
>
> Thanks
> Rick
>
> 1. For each record update field1 with subsquery
> Assume cursor is declared
> FOR cursor_rec IN new_patients_cur LOOP
> UPDATE <table>
> SET field1 =
> (SELECT value
> FROM table
> WHERE ...)
> WHERE ....
> END LOOP;
>
> 2. For each record load nested table with data then update all records with
> a single FORALL
>
> t_type1 IS TABLE OF table1.field1%TYPE;
> v_type1 t_type1(10000);
>
> /* Load the PLSQL nested table */
> FOR cursor_rec IN new_patients_cur LOOP
> v_loop_ctr := v_loop_ctr + 1;
> v_type1 := cursor_rec.field1;
> END LOOP;
>
> /* INSERT all 10,000 records with on context switch */
> FORALL v_count IN 1...10000)
> UPDATE field1 = v_type1(v_count);
>

Give it a try, with SET TIMING ON. No such thing as seeing to believe.

-- 
Regards,

Stephane Faroult
Oriole Ltd
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Stephane Faroult
  INET: sfaroult_at_oriole.com

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