× The internal search function is temporarily non-functional. The current search engine is no longer viable and we are researching alternatives.
As a stop gap measure, we are using Google's custom search engine service.
If you know of an easy to use, open source, search engine ... please contact support@midrange.com.


  1.  Home
  2. MIDRANGE-L
  3. January 2020

Re: Why Table Scan?

Hi Justin

<> will often trigger a table scan, even if there are indexes on the tables. There's a section in the VE output with reasons for the choices the optimizer made, as I recall. And suggestions for indexes.

Can you replace the <> with an exception join? It might have better luck.

There is also considerable help in that application for the performance options in a query.

HTH
Vern

On 1/8/2020 10:25 AM, Justin Taylor wrote:
I'm troubleshooting performance of a query. VE is showing a Table Scan, and I don't know why it's doing a Table Scan. It's on joining two views. The JOIN ON is just <> or = conditions. The Optimized Messages tab shows "Debug messages are not available".

Any suggestions on this?

Thanks




As an Amazon Associate we earn from qualifying purchases.

This thread ...
Follow-Ups:
Replies:
Follow On AppleNews
Return to Archive home page | Return to MIDRANGE.COM home page

This mailing list archive is Copyright 1997-2024 by midrange.com 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.