Execution plan help

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Execution plan help

marcelo salgado

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Points: 287
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August 24, 2022 at 11:43 pm

#4080306

Explain what are the differences between the following execution plans and which of them would you select as the best?

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Jeff Moden SSC Guru Points: 1003853 More actions · Answer 1

The Seek is probably a Seek followed by a range scan of the full table, which probably has little if any advantage over the scan. I only use the Execution plan to help me see what is going on. I never make a final choice based on the execution plan. The key would be to run the against your choice of tools... SET STATISTICS TIME,IO ON or SQL Profiler or Extended Events and see which one is the actual winner.

And I never go by % of batch. I can intentionally write a query where the 0% of two batches is actually a whole lot worse than the 100% batch, which can run almost instantaneously while the 0% toting batch takes a minute to run.

And the only way to truly understand the differences between those execution plans would be to dive into the properties of each block but we can't do that because you posted a graphic rather that attaching and actual viable execution plan. Sure, someone could explain a bit like I did above, but you never know for sure until you view the properties of the nodes.

--Jeff Moden

RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
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Johan Bijnens SSC Guru Points: 135255 More actions · Answer 2

Performance has a cost.

That cost starts with declaring the correct data type for columns !

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Ant-Green SSC Guru Points: 113445 More actions · Answer 3

LEFT is also non-sargable so you will get a scan with that second query.

To make it sargable you would need to use LIKE instead. Thanks

Johan Bijnens SSC Guru Points: 135255 More actions · Answer 4

Ant-Green wrote:

LEFT is also non-sargable so you will get a scan with that second query.
To make it sargable you would need to use LIKE instead. Thanks

"Like" does not work with numeric data typed columns.