We Built a Free SQL Server Knowledge Base (256 Articles and Counting)

Over the past few weeks we've published something I wish existed when I started doing SQL Server performance work: a free, searchable knowledge base covering wait types, DMVs, error codes, and common troubleshooting scenarios. As of today it has 256 articles, and we're still adding to it.

You can browse the whole thing at autodba.samix-technology.com/sql-server. No login, no paywall, no email gate. Just the information.

What's In It

The knowledge base is split into four sections:

Wait Types (196 articles). Every significant SQL Server wait type with an explanation of what causes it, when it's actually a problem vs. background noise, diagnostic queries to investigate, and concrete steps to fix it. From the common ones like CXPACKET and PAGEIOLATCH_SH to the obscure ones you hit once a year and have to Google every time.

DMVs (30 articles). The dynamic management views that matter most for performance work. Not just the column definitions — Microsoft's docs cover that — but how to actually use them. What to join to what, how to interpret the numbers, and the queries we run against them in real investigations. sys.dm_os_wait_stats, sys.dm_exec_query_stats, sys.dm_io_virtual_file_stats, and more.

Error Codes (18 articles). The error messages that come up most often in production. Error 18456 alone gets its own deep dive because the login failure states are a maze. We also cover 823, 824, and other errors where the standard advice of "check the error log" isn't enough.

Troubleshooting Guides (12 articles). Scenario-based guides for the problems DBAs deal with regularly: deadlocks, blocking chains, parameter sniffing, tempdb contention, memory pressure, and others. Each one walks through diagnosis, root cause analysis, and resolution.

Why We Built It

The short answer: because the existing resources are scattered and incomplete.

If you want to understand a wait type today, you search for it and get a Stack Overflow answer from 2014, a blog post that covers the basics but not the edge cases, and Microsoft's official docs which give you a one-sentence description. You end up with 15 tabs open, cross-referencing, trying to figure out what actually applies to your situation.

We wanted a single place where you could look up any wait type, DMV, or error code and get the full picture: what it means, when it matters, how to diagnose it, and what to do about it. With actual queries you can copy, paste, and run.

The longer answer: this is the reference material that feeds into AutoDBA's diagnostics. When AutoDBA analyses your SQL Server and tells you that your WRITELOG waits are elevated, it's drawing on the same knowledge that's now published in these articles. Making it public means you can verify our reasoning and use it whether or not you're an AutoDBA customer.

Every Article Has Runnable Queries

This was a non-negotiable for us. Theory is useful, but when you're troubleshooting a production issue at 2am, you need a query you can run right now.

Every wait type article includes a diagnostic query that shows you current wait statistics for that specific wait. Every DMV article includes the joins and filters that give you useful output rather than raw data. Every troubleshooting guide includes step-by-step queries that walk you from symptom to root cause.

For example, the blocking chains article doesn't just explain what blocking is. It gives you a recursive CTE that maps the entire blocking tree, shows you the head blocker's query text, and tells you how to determine whether the blocker is waiting on an application, a disk, or a lock.

How to Use It

Each section has a search bar. Type a wait type name, error number, or DMV name and it filters instantly. Every article is color-coded by severity so you can quickly tell whether something needs immediate attention or is informational.

If you're starting a performance investigation and don't know where to begin, start with the troubleshooting guides. They're organized by symptom: "my server is slow," "queries are timing out," "disk is maxed out." Each one will point you to the relevant wait types and DMVs.

If you already know what you're looking at — you've identified RESOURCE_SEMAPHORE waits, or you're seeing error 823 — go directly to that article for the diagnostic queries and fix steps.

What's Next

We're continuing to add content. The wait types section is the most complete right now, but we're expanding the DMV and troubleshooting sections over the coming weeks. If there's a topic you'd like covered, let us know.

And if you want automated analysis that uses all of this knowledge against your actual SQL Server data, try AutoDBA. The diagnostic scan is free and takes about 60 seconds.