ASYNC_NETWORK_IO wait stats mean SQL Server has results ready and is waiting for the application to read them. On Night 21 at the Clipboard Diner, hot plates pile up at the pass while Quinn tells a long story at table 4. Learn the causes in the order I find them, two queries that name the slow program, and why the fixes live in the application.
MSQL_XP Wait Stats: Extended Procedures and External Code
MSQL_XP wait stats measure the time a query waits while an extended stored procedure such as xp_cmdshell or xp_dirtree runs. On Night 20 at the Clipboard Diner, an outside caterer takes over one station behind a curtain. Then two queries show you which session is waiting and which procedure it called, and the fixes move that work outside SQL Server.
EXISTS: A Row Containing NULL Still Exists
EXISTS answers whether qualifying rows exist. Keep missing values separate from missing rows and preserve the intended correlation.
BACKUPIO Wait Stats: Why Backups Wait
BACKUPIO wait stats show a backup waiting on its own I/O, either reading the database or writing the backup file. On Night 14 at the Clipboard Diner, the night truck waits for empty crates and a slow gravel lot. You’ll see how BACKUPIO, BACKUPBUFFER and BACKUPTHREAD fit together, how to measure backup speed from msdb, and which fixes to try first, including ZSTD compression in SQL Server 2025.
Harmless Wait Stats: Waits You Can Safely Ignore
Harmless wait stats come from background tasks that sleep on purpose, such as the lazy writer, the deadlock monitor and the full-text scheduler. On Night 13 at the Clipboard Diner, the biggest numbers on Casey’s clipboard belong to a sleeping baker and an idle dishwasher. Two queries show how much of your wait list they take up and how to judge an unknown wait yourself.
IO_COMPLETION Wait Stats: Spills, Sorts and File Growth
IO_COMPLETION wait stats measure queries waiting on disk work that isn’t a normal data page read, such as sorts and hashes that spill to tempdb. On Night 10 at the Clipboard Diner, a sheet cake for twelve turns out to be for sixty. Learn why spills happen, how to find them, and what SQL Server 2022 changed for log file growth.
PAGEIOLATCH Wait Stats: Waiting for Data From Disk
PAGEIOLATCH wait stats measure queries waiting while data pages are read from disk into memory. On Night 9 at the Clipboard Diner, the prep counter is too small for the menu and the cooks keep sending for things from the basement. Learn the two causes, how to read file latency per file, and the fixes in order.