Query Tuning With The APPLY Operator

Daniel Janik walks through using the APPLY operator to tune a couple of queries:

Recently we were doing a project that heavily focused on query tuning and many tables had various outer joins. My co-worker pointed out that many of these could be converted to an apply rather than a join.

Apply gives you both CROSS and OUTER. Think of CROSS APPLY like an INNER JOIN and OUTER APPLY like an OUTER JOIN.

Let’s compare some code to see how APPLY stacks up.

I like the APPLY operator so much that I created an entire presentation on it.  It’s not a cure-all by any means, but if you understand the intent, you can find places where it improves your code significantly.

Related Posts

Reading SQL Server Error Logs

Thomas Rushton has a script for us: Why Script This? What’s Wrong With SSMS’s GUI?Well, although SSMS does allow you to look at the error logs, it’s not very helpful for filtering – you can only filter for items that match, rather than exclude items. There are a few other filters as well – I […]

Read More

Rounding to Intervals in Various Languages

Dave Mason doesn’t like rounding to intervals very much in T-SQL: If I had to choose any of these options for production, I’d probably go with Query 1, just because I think it would make the most sense to any other developer that might encounter it (including future me, who probably wouldn’t remember writing the […]

Read More

Categories

April 2018
MTWTFSS
« Mar May »
 1
2345678
9101112131415
16171819202122
23242526272829
30