A simple puzzle: why does SQL Server show such a complicated execution plan for a single row, single table query on WideWorldImporters? Try to solve it.
Local Variable Estimates: Why the Density Vector Wins
Understand local variable estimates with skewed data, density calculations, parameter comparisons, and targeted OPTION RECOMPILE tests.
The Tipping Point: Why SQL Server Skips Your Nonclustered Index
Find the tipping point where key lookups cost more than a scan, then compare covering and filtered indexes with measured reads.
How to Force a Parallel Execution Plan for a Query? – Interview Question of the Week #170
A customer asked how to force a Parallel Execution Plan for a query. Here are two methods, including QUERYTRACEON 8649, with a simple example.
SQL SERVER – FIX: Arithmetic Overflow Error in Object Execution Statistics Report in Management Studio
The SSMS Object Execution Statistics report suddenly failed for a client with Msg 8115, arithmetic overflow converting to int. Here is why and what to do.
Automatic Plan Correction: Reading SQL Server’s Tuning Advice
Read automatic plan correction advice, compare regressed and recommended plans, and verify that forcing the last good plan held.
Partition Elimination: Proving a Query Reads Only What It Needs
Prove partition elimination with the actual plan, test date predicates, and use $PARTITION to check which slice SQL Server targets.