Secret To Optimizing SQL Queries – Understand The SQL Execution Order
- Execution Plan
- Search Argument Able (SARGABLE)
- Index Scan (bigTransactionalHistory)
- Stream Aggregare (Aggregate)
- Parallelism (Repartition Streams)
- Stream Aggregare (Aggregate)
- Clustered Index Scan (bigProduct)
- Parallelsim (Repartition Streams)
- Merge Join (Inner Join)
- Parallelism (Gather Streams)
To write sargable queries
- Avoid using functions or calculations on indexed columns in the WHERE clause
- Use direct comparisons when possible, instead of wrapping the column in a function
- If we need to use a function on a column, consider creating a computed column or a function-based index, if the database system supports it
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