Investigate multi-column statistics with correlated city and state values, density vectors, and plans before expecting better estimates.
SQL SERVER – Find Statistics Update Date – Update Statistics
Stale statistics can hurt a query plan. Use STATS_DATE to find the statistics update date for each index, then update them if they look outdated.
SQL SERVER – Enable Automatic Statistic Update on Database
Automatic statistics updates respond to changing data and query needs. I inspect the setting and estimates before treating it as a tuning fix.
Filtered Indexes and Where They Help
Filtered indexes help SQL Server target active rows in a larger table; learn useful predicates, parameter limitations, and how to verify plan choices.
SQL SERVER – SQL Server Management Studio and Client Statistics
Query cost does not tell you how much data a query returns. Client statistics in SQL Server Management Studio do, and there are three ways to turn them on.
Columns With No Statistics: Read Each Warning
A columns-with-no-statistics warning needs a column-by-column investigation. Compare warning lists before and after targeted statistics creation, and check the actual query behavior before deciding that a missing statistic caused poor performance.
Reading the Warnings in an Execution Plan
Warnings in an execution plan can reveal conversions, missing statistics, and spills; read each warning in workload context.