SQL Server Performance & Troubleshooting – Where Milliseconds Matter 🚀

Before we dive into today's topic, if you missed my previous post you can take a look at Check Parameter Sniffing in 45 Seconds. Execution Engine | Part 15 . 👉 If you found this deep-dive helpful, feel free to check out the ads—your support helps me keep creating high-quality SQL Server content for the community. SQL Server: Why Your Queries Return Wrong Results (And You Don’t Know It) Silent Killers | Part 16 Performance is nothing without accuracy. Stop trusting your reports blindly. Performance is irrelevant if the data is wrong. In this post, I’ll expose the silent killers that cause SQL Server to return incorrect results without throwing a single error—a nightmare for any Senior DBA. 🧠 TL;DR BOX ✔️ NOT IN + NULL: If your subquery contains a single NULL, your entire result set becomes empty 💣 ✔️ NOLOCK (Dirty Reads): Can cau...

Before we dive into today's topic, if you missed my previous post you can take a look at Check Index Fragmentation in 45 Seconds. Execution Engine | Part 14 . 👉 If you found this deep-dive helpful, feel free to check out the ads—your support helps me keep creating high-quality SQL Server content for the community. Check SQL Server Parameter Sniffing in 45 Seconds Execution Engine | Part 15 Stop chasing ghosts and start identifying plan cache poisoning instantly. In this post, I’ll show you how to detect Parameter Sniffing in under 45 seconds using DMVs. This is the #1 reason why a query is fast in SSMS but crawls in your application! 🧠 TL;DR BOX ✔️ What: SQL Server creates a plan based on the *first* parameter provided (the "sniffed" value). ✔️ The Trap: A plan optimized for 1 row is disastrous when the next execution needs 1,000,0...

Before we dive into today's topic, if you missed my previous post you can take a look at Check Missing Indexes (and Why They Lie) in 45 Seconds. Execution Engine | Part 13 . 👉 If you found this deep-dive helpful, feel free to check out the ads—your support helps me keep creating high-quality SQL Server content for the community. Check SQL Server Index Fragmentation in 45 Seconds Execution Engine | Part 14 Stop wasting maintenance windows on fragmentation that doesn't affect performance. Most DBAs obsess over fragmentation percentages without realizing that modern storage and small table sizes make most defragmentation efforts useless. In this post, I will show you how to identify the only indexes that actually need your attention. 🧠 TL;DR BOX ✔️ Ignore small indexes: If an index has fewer than 1,000 pages, fragmentation is statistically irrelevant...

Before we dive into today's topic, if you missed my previous post you can take a look at Check Cardinality Estimation Issues in 45 Seconds. Execution Engine | Part 12 . 👉 If you found this deep-dive helpful, feel free to check out the ads—your support helps me keep creating high-quality SQL Server content for the community. Check SQL Server Missing Indexes (and Why They Lie) in 45 Seconds Execution Engine Deep Dive | Part 13 In this post, you will learn how to extract the highest impact missing indexes from the plan cache and why blindly applying "green text" suggestions can destroy your server's write performance. 🧠 TL;DR BOX ✔️ Use sys.dm_db_missing_index_details to identify gaps the Optimizer noticed during compilation. ✔️ The "Missing Index" feature is a hint , not a command; it doesn't consider existing indexes or write o...

Before we dive into today's topic, if you missed my previous post you can take a look at Check Execution Plans in 45 Seconds . 👉 If you found this deep-dive helpful, feel free to check out the ads—your support helps me keep creating high-quality SQL Server content for the community. Check SQL Server Cardinality Estimation Issues in 45 Seconds Execution Engine Deep Dive | Part 12 In this post, I will show you how to identify the silent killer of performance: the "Estimate vs Actual" row gap. Mastering Cardinality Estimation is the difference between a sub-second response and a server-wide timeout. 🧠 TL;DR BOX ✔️ Cardinality Estimation (CE) is the Optimizer's prediction of how many rows a query will process. ✔️ A massive discrepancy between Estimated and Actual rows leads to sub-optimal join choices and memory grant spills. ✔️ Primary culpri...

Before we dive into today's topic, if you missed my previous post you can take a look at SQL Server 2025 Built-in Chunking and Vector Support AI Functions, the Brutal Truth. From SQL to AI series, Part 1 . 👉 If you found this deep-dive helpful, feel free to check out the ads—your support helps me keep creating high-quality SQL Server content for the community. Check SQL Server Execution Plans in 45 Seconds Master the Execution Engine: The "45 Seconds DBA Series" | Part 11 Stop guessing why your queries are slow. In 45 seconds, I’ll show you how to intercept the Query Optimizer's roadmap and pinpoint bottlenecks before they kill your production environment! 🧠 TL;DR ✔️ Use DMVs to extract XML plans for currently running requests instantly 🛠️ ✔️ Identify Index Scans vs. Seeks to verify SARGability 🔍 ✔️ Spot "Fat Arrows...