The latest articles on DEV Community by DanielNnadi (@danielnnadi). https://dev.to/danielnnadi https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F3981516%2Fea105714-425a-457a-b9ad-30de671cd5a8.png https://dev.to/danielnnadi en DanielNnadi Fri, 12 Jun 2026 15:35:45 +0000 https://dev.to/danielnnadi/how-i-cut-sql-query-time-from-45-seconds-to-8-seconds-on-23-million-rows-o3e https://dev.to/danielnnadi/how-i-cut-sql-query-time-from-45-seconds-to-8-seconds-on-23-million-rows-o3e <p>I inherited a SQL Server database with 2.3 million rows. Queries took 45 seconds. Users were frustrated. Dashboards timed out.</p> <p>Here is exactly what I did.</p> <p>Step 1: Find the slowest queries</p> <p>I used SQL Server's query store to identify the top 10 worst performing queries.</p> <p>Step 2: Check the execution plan</p> <p>Missing index warnings everywhere. Also saw table scans on a 2 million row table.</p> <p>Step 3: Add targeted indexes</p> <p>Created two non-clustered indexes on the most filtered columns. No over-indexing. Just what the queries actually needed.</p> <p>Step 4: Rewrite the worst join</p> <p>One query was joining 6 tables with a cross apply that made no sense. Restructured to inner joins with proper filter ordering.</p> <p>The result</p> <p>45 seconds down to 8 seconds. An 82% improvement. Real-time dashboards started working again.</p> <p>Key lesson</p> <p>Check what is actually slow before changing anything. Most people skip this and waste time optimizing the wrong thing.</p> <p>What is your fastest query optimization win?</p> sql database performance dataengineering DanielNnadi Fri, 12 Jun 2026 15:35:45 +0000 https://dev.to/danielnnadi/how-i-cut-sql-query-time-from-45-seconds-to-8-seconds-on-23-million-rows-45o4 https://dev.to/danielnnadi/how-i-cut-sql-query-time-from-45-seconds-to-8-seconds-on-23-million-rows-45o4 <p>I inherited a SQL Server database with 2.3 million rows. Queries took 45 seconds. Users were frustrated. Dashboards timed out.</p> <p>Here is exactly what I did.</p> <p>Step 1: Find the slowest queries</p> <p>I used SQL Server's query store to identify the top 10 worst performing queries.</p> <p>Step 2: Check the execution plan</p> <p>Missing index warnings everywhere. Also saw table scans on a 2 million row table.</p> <p>Step 3: Add targeted indexes</p> <p>Created two non-clustered indexes on the most filtered columns. No over-indexing. Just what the queries actually needed.</p> <p>Step 4: Rewrite the worst join</p> <p>One query was joining 6 tables with a cross apply that made no sense. Restructured to inner joins with proper filter ordering.</p> <p>The result</p> <p>45 seconds down to 8 seconds. An 82% improvement. Real-time dashboards started working again.</p> <p>Key lesson</p> <p>Check what is actually slow before changing anything. Most people skip this and waste time optimizing the wrong thing.</p> <p>What is your fastest query optimization win?</p> sql database performance dataengineering