The query engine is optimized for joins.

Many times, EXISTS or a IN will be re-written as a join.

An exception join, as shown, will not bring try to bring in any data from
the child table.


On Fri, Dec 20, 2019 at 8:47 AM Darren Strong <darren@xxxxxxxxx> wrote:

I've seen NOT EXISTS and JOINS suggested. My opinion is that a NOT EXSISTS
will perform the best for you. If you don't actually need a value from the
child table, a join brings the possibility of a higher performance hit vs.
the NOT EXISTS, which is accurately telling the optimizer that you don't
want anything from the secondary table except to know if a record exists

This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing list
To post a message email: MIDRANGE-L@xxxxxxxxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
or email: MIDRANGE-L-request@xxxxxxxxxxxxxxxxxx
Before posting, please take a moment to review the archives

Please contact support@xxxxxxxxxxxx for any subscription related

Help support by shopping at with our affiliate

As an Amazon Associate we earn from qualifying purchases.

This thread ...


Follow On AppleNews
Return to Archive home page | Return to MIDRANGE.COM home page

This mailing list archive is Copyright 1997-2022 by and David Gibbs as a compilation work. Use of the archive is restricted to research of a business or technical nature. Any other uses are prohibited. Full details are available on our policy page. If you have questions about this, please contact [javascript protected email address].

Operating expenses for this site are earned using the Amazon Associate program and Google Adsense.