seniorT-SQL
What is PFS, GAM, and SGAM pages in tempdb architecture?
Updated May 17, 2026
Short answer
PFS, GAM, and SGAM are system pages that track allocation state in SQL Server.
Deep explanation
PFS tracks page free space, GAM tracks global allocation of extents, and SGAM tracks mixed extent usage. Contention on these pages is a major cause of tempdb bottlenecks in high concurrency systems.
Unlock with a Pro subscription to view this section.
View pricingReal-world example
No real-world example available yet.
Unlock with a Pro subscription to view this section.
Upgrade to ProCommon mistakes
No common mistakes listed yet.
Unlock with a Pro subscription to view this section.
Upgrade to ProFollow-up questions
No follow-up questions available yet.
Unlock with a Pro subscription to view this section.
Upgrade to Pro