July 18, 2016 at 3:40 am
Hi Guys,
I have a question about using covering indexes within joins. If I use 1 column in a covering index and use it in a joins, I get a scan within my query plan.
Should I include all the columns in my joins that reference the covering index? The index has 3 columns but no 'includes' columns.
Regards
IC
July 18, 2016 at 3:45 am
What kind of scan - table scan, clustered index scan, or non clustered index scan? Please post the actual execution plan.
John
July 18, 2016 at 3:59 am
Further on John's reply, we need the table structures, the query and the actual execution plan, without the information it's only wild guesses.
😎
July 18, 2016 at 4:08 am
Don't worry....I already figured it out.
Its a clustered index scan and when I include both indexes in the joins it returns a Seek instead of a Scan.
July 18, 2016 at 6:21 am
Imke Cronje (7/18/2016)
Don't worry....I already figured it out.Its a clustered index scan and when I include both indexes in the joins it returns a Seek instead of a Scan.
Now all you have to worry about is how many times it does the seek. Seriously. See the properties window on the icon.
As a bit of a sidebar, a seek on the execution plan is not always better than a scan, especially if a seek is done once for each row.
--Jeff Moden
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