https://www.sqlserver70.com/tags/sp_updatestats/Recent content in Sp_updatestats on SQL Server ScriptsHugo -- gohugo.ioenSQLServer70.comWed, 17 Jun 2026 00:00:00 +0000https://www.sqlserver70.com/post/sql-server-update-statistics-guide/Wed, 17 Jun 2026 00:00:00 +0000https://www.sqlserver70.com/post/sql-server-update-statistics-guide/ <p>A query that ran in milliseconds last month now scans a million rows and spills to tempdb. Nothing changed in the code — but the data grew, and the statistics the optimizer relies on went stale, so its row estimates drifted far from reality and it chose a bad plan. Refreshing statistics is the fix, and knowing how and when to do it is core DBA work.</p> <script async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-1012089347386563" crossorigin="anonymous"></script> <ins class="adsbygoogle" style="display:inline-block;width:728px;height:90px" data-ad-client="ca-pub-1012089347386563" data-ad-slot="8593449130"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> <h2 id="purpose-and-overview">Purpose and Overview</h2> <p>SQL Server's query optimizer is cost-based: it estimates how many rows each operator will process and picks a plan accordingly. Those estimates come from statistics objects — histograms and density vectors that describe the distribution of values in a column or index. When data changes but statistics do not, estimates degrade, and the optimizer can choose nested loops where a hash join belongs, or under-size a memory grant.</p>