Re: Q: Performance
From: Alexandr I. Alesinsky <al_at_investor.kharkov.ua>
Date: 1995/06/07
Message-ID: <ABJsLrlGDB_at_investor.kharkov.ua>#1/1
Date: 1995/06/07
Message-ID: <ABJsLrlGDB_at_investor.kharkov.ua>#1/1
>Hello,
>
>Because of daily usage of large tables, I have some performance questions I'd
>like answers to:
>
>1. What's faster:
>-----------------
>A. select rownum from A where A.field1 NOT IN
> (select fieldA from B)
>B. select rownum from A where NOT EXISTS
> (select 'x' from B where A.field1 = B.fieldA)
>C. Anything else
"B" is significantly faster if table B in indexed on fieldA (details see in Chapter 5 of Application Developer's Guide).
>
>3. What's faster:
>-----------------
>A. Insert into ... values (....) as select ...
>B. Insert with a cursor
>
A is faster.
Alexandr Alesinsky,
JSV Investor
Received on Wed Jun 07 1995 - 00:00:00 CEST