A Rocket Scientist Perspective on Index Column Selection
summary
Walks through hands-on demos against AdventureWorks2017 big using provided scripts and execution plans to prove index column order matters: a 26 MB nonclustered covering index drops a query from ~29,295 logical reads to ~264 (sometimes to 4–5 reads) by ordering status before territory, and reversing order raises reads and cost. Shows covered indexes let UPDATEs use index seeks instead of clustered scans, and that an unused secondary index can force worse plans.
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chapters (5)
- 0:00Start
- 3:57Overview
- 35:33Covered Indexes for Update Statements
- 41:30Create a Covered Index
- 44:58Conclusions
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