Re: Which is more efficient For vs FORALL

Rick,

I'd suggest:

SELECT <table1_field1_name>, <table1_field2_name> BULK COLLECT INTO v_array, c_array

    FROM <table1_name>
    WHERE ... then do 'for all':

FORALL nJ IN 1..v_array.COUNT

    UPDATE <table2_name>
    SET <table2_field1_name> = v_array(nJ)     WHERE <table2_field2_name> = c_array(nJ);

Igor Neyman, OCP DBA
ineyman_at_perceptron.com

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Monday, February 04, 2002 1:15 PM

> 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);
>
>
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author:
> INET: Rick_Cale_at_teamhealth.com
>
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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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