SQL Server For Beginners: Why Functions And Table Variables Make Queries Slow Lecture

Why Functions Make Queries Slow


Going Further


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2 thoughts on “SQL Server For Beginners: Why Functions And Table Variables Make Queries Slow Lecture

  1. WOW. My takeaway from this is that table variables are slow and temp tables are the way to go if you need to. I switched out a query that was running insanely slow and had table variables to temp tables. I am embarrassed to say that the previous run time was exceeding 5 hours, and it wasn’t a whole lot of data. It was previously 2 hours, but my boss had me expand the scope and it just took forever. I wasn’t aware my stupid table variables were the cause; it is doing quite a lot of case statements and mathematical equations, but nothing that’s 5 hours of craziness.

    I switched my table definitions to temp tables instead and holy bananas, 18 seconds! It’s so insane. I can’t believe I was doing that so bad for so long. I thought the table variables were making things cleaner. Most scripts were a tolerable few minutes. Off to get rid of table variables in all of my scripts.

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