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⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: ASYNC_NETWORK_IO Wait TypeRelated pillar: Performance & Troubleshooting ⚡These waits are SQL Server calling Windows networking functions, and the one that matters is PREEMPTIVE_OS_GETADDRINFO: a DNS name lookup. Slow DNS makes every outbound connection by name stall, from linked servers to Availability…

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⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: SOS_SCHEDULER_YIELD Wait TypeRelated pillar: Performance & Troubleshooting Is It a Problem? The wait itself is not; it lasts as long as the external command does. It was zero on our SQL Server 2025 lab. Get Wait Statistics does not filter it…

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⏳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 SQL Server reading the Windows registry. Normally trivial, but a known SQL Server 2022 bug made it a contention point, fixed in 2022 CU5. Run the check to see your build and…

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⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: SOS_SCHEDULER_YIELD Wait TypeRelated pillar: Performance & Troubleshooting Is It a Problem? The call itself is quick when Windows is healthy; our SQL Server 2025 lab had about 4,700 waits totalling 13 seconds in a day. Get Wait Statistics does not filter…

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⏳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 authorisation go through many security functions, 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, FREECREDENTIALSHANDLE,…

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⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: ASYNC_NETWORK_IO Wait TypeRelated pillar: Performance & Troubleshooting Is It a Problem? Read it the way you read ASYNC_NETWORK_IO: SQL Server has results and is waiting on the client. It was zero on our SQL Server 2025 lab. Get Wait Statistics does…

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⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: SOS_SCHEDULER_YIELD Wait TypeRelated pillar: Performance & Troubleshooting Is It a Problem? No. It is not reported as a contention point, and each occurrence is an endpoint stopping rather than workload; our SQL Server 2025 lab had a single wait of a…

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⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: SOS_SCHEDULER_YIELD Wait TypeRelated pillar: Performance & Troubleshooting Is It a Problem? No. It is not a known contention point; our SQL Server 2025 lab had a single wait. Get Wait Statistics does not filter it out, so if it ranks, you…

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⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: ASYNC_NETWORK_IO Wait TypeRelated pillar: Performance & Troubleshooting The PREEMPTIVE_XE_* waits are Extended Events calling outside SQL Server’s scheduler, and this page covers the set: PREEMPTIVE_XE_SESSIONCOMMIT, TARGETINIT, TARGETFINALIZE, GETTARGETSTATE, CALLBACKEXECUTE, DISPATCHER, ENGINEINIT and TIMERRUN. Microsoft lists them all as internal use only.…

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⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: LCK_M_X, LCK_M_S, and LCK_M_U Wait TypesRelated pillar: Performance & Troubleshooting Is It a Problem? It measures a deliberate action. ROLLBACK IMMEDIATE ends transactions straight away, but rollback itself takes time, and the ALTER DATABASE waits for all of it. Our SQL…

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