Resources
Books
Microsoft SQL Server 2012 Internals by Kalen Delaney et al
- Previous editions
Pro SQL Server Internals by Dmitri Korotkevitch
Blogs
- The "Inside the Storage Engine" posts were the starting point of Internals Viewer
- Detailed optimizer and query processor internals information
Websites
SQLServerFast - Execution Plan Reference
- Detailed information about execution plan operators, including algorithms
Documentation
Microsoft Learn - SQL - Internals & architecture
Internals Viewer
Internals Viewer itself was used to decipher undocumented functionality. For example, at the time PAGE and ROW level compression was not detailed anywhere, so adding it involved reverse engineering with DBCC PAGE and the decode selection functionality in the Page Viewer, translating bytes into possible values.
The repo includes a verification tool that compares Internals Viewer vs DBCC PAGE to verify the row cracking.