Category: Wait Types

⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: SOS_SCHEDULER_YIELD Wait TypeRelated pillar: Performance & Troubleshooting PREEMPTIVE_OS_GETDISKFREESPACE is recorded when a thread calls the Windows GetDiskFreeSpace function to check a volume’s free space. Callers include the engine (before file growth, during certain file operations) and, prominently, monitoring queries: sys.dm_os_volume_stats, xp_fixeddrives,…

⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: SOS_SCHEDULER_YIELD Wait TypeRelated pillar: Performance & Troubleshooting PREEMPTIVE_OS_GETPROCADDRESS is recorded while a thread calls the Windows GetProcAddress function to resolve an extended stored procedure’s entry point inside its DLL. Every XP call needs this lookup, so instances that use extended stored…

⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: SOS_SCHEDULER_YIELD Wait TypeRelated pillar: Performance & Troubleshooting Three preemptive waits track Windows DLL handling, and this page covers them together: PREEMPTIVE_OS_LOADLIBRARY (loading a DLL into the process), PREEMPTIVE_OS_FREELIBRARY (unloading one), and PREEMPTIVE_OS_LIBRARYOPS (the generic bucket for other library operations). Their callers…

⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: SOS_SCHEDULER_YIELD Wait TypeRelated pillar: Performance & Troubleshooting PREEMPTIVE_OS_LOOKUPACCOUNTSID is recorded while a thread calls the Windows LookupAccountSid function, which translates a security identifier (SID) into an account name. For domain accounts that translation can leave the server entirely and query a…

⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: SOS_SCHEDULER_YIELD Wait TypeRelated pillar: Performance & Troubleshooting The remaining one-API preemptive waits do not warrant a page each, so this reference covers them together. All share the standard mechanics: the thread runs under Windows control (state RUNNING) until the call returns,…

⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: ASYNC_NETWORK_IO Wait TypeRelated pillar: Performance & Troubleshooting Four preemptive waits track Windows networking APIs, and this page covers them together: Together they are the OS-call basement under SQL Server’s outbound and transport networking. Are They a Problem? At trace levels, no.…

⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: SOS_SCHEDULER_YIELD Wait TypeRelated pillar: Performance & Troubleshooting PREEMPTIVE_OS_PIPEOPS is recorded when a thread calls out to Windows functions that work with pipes, and in DBA reality that means one thing almost every time: xp_cmdshell. SQL Server launches the external command and…

⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: SOS_SCHEDULER_YIELD Wait TypeRelated pillar: Performance & Troubleshooting PREEMPTIVE_OS_QUERYREGISTRY is a generic wait for threads calling Windows registry functions. SQL Server consults the registry for assorted configuration (service settings, network configuration, some feature lookups), and xp_regread and friends route here too. The…

⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: SOS_SCHEDULER_YIELD Wait TypeRelated pillar: Performance & Troubleshooting PREEMPTIVE_OS_REPORTEVENT is recorded when a thread calls the Windows ReportEvent function, writing an entry to the Windows event log. SQL Server mirrors significant error log messages to the Application event log, and features like…

⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: SOS_SCHEDULER_YIELD Wait TypeRelated pillar: Performance & Troubleshooting Windows authentication and authorization involve a parade of security APIs, and SQL Server has a preemptive wait for each. This page covers the family: PREEMPTIVE_OS_ACCEPTSECURITYCONTEXT, ACQUIRECREDENTIALSHANDLE, AUTHORIZATIONOPS, AUTHZGETINFORMATIONFROMCONTEXT, AUTHZINITIALIZECONTEXTFROMSID, AUTHZINITIALIZERESOURCEMANAGER, COMPLETEAUTHTOKEN, DECRYPTMESSAGE, ENCRYPTMESSAGE, DELETESECURITYCONTEXT,…