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  • QUERY_TASK_ENQUEUE_MUTEX Wait Type in SQL Server

    ⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: CXPACKET and CXCONSUMER Wait TypesRelated pillar: Performance & Troubleshooting Is It a Problem? No. It is not a known contention point, and it was zero on our SQL Server 2025 lab. Get Wait Statistics does not filter it out, so if…

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  • REDO_THREAD_PENDING_WORK Wait Type in SQL Server

    ⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: HADR_SYNC_COMMIT Wait TypeRelated pillar: High Availability Is It a Problem? No. It is not a known contention point, expects high wait times on an AG generating very little log, and filters it as benign; Get Wait Statistics filters it out by…

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  • REPLICA_WRITES Wait Type in SQL Server

    ⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: IO_COMPLETION Wait TypeRelated pillar: High Availability Is It a Problem? Small amounts during DBCC CHECKDB on a busy database are expected. It is worth a look when it stretches integrity check times, or when user database snapshots make writes to the…

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  • REQUEST_DISPENSER_PAUSE Wait Type in SQL Server

    ⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: BACKUPIO and BACKUPBUFFER Wait TypesRelated pillar: Performance & Troubleshooting Is It a Problem? Only as much as the freeze it leads into. A quick drain is barely noticeable; long waits mean in-flight I/O took a while to finish before the freeze…

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  • RESERVED_MEMORY_ALLOCATION_EXT Wait Type in SQL Server

    ⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: RESOURCE_SEMAPHORE Wait TypeRelated pillar: Performance & Troubleshooting Is It a Problem? Usually not; the normal profile is many tiny waits. Our SQL Server 2025 lab had about 318,000 waits averaging 0.06 ms in a day. Get Wait Statistics does not filter…

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  • RESOURCE_GOVERNOR_IDLE Wait Type in SQL Server

    ⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: SOS_SCHEDULER_YIELD Wait TypeRelated pillar: Performance & Troubleshooting ⚡RESOURCE_GOVERNOR_IDLE is a query being held idle on purpose, because Resource Governor has a hard CPU cap on its pool. It is a policy reporting what it denied, not a fault. Run the check…

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  • RESOURCE_SEMAPHORE_MUTEX Wait Type in SQL Server

    ⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: RESOURCE_SEMAPHORE Wait TypeRelated pillar: Performance & Troubleshooting Is It a Problem? Not directly. It is not reported as a contention point in its own right, and its waits are normally tiny; our SQL Server 2025 lab had 237 waits and 0.3…

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  • RESOURCE_SEMAPHORE_SMALL_QUERY Wait Type in SQL Server

    ⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: RESOURCE_SEMAPHORE Wait TypeRelated pillar: Performance & Troubleshooting ⚡RESOURCE_SEMAPHORE_SMALL_QUERY is a small query waiting for a memory grant, documented for SQL Server 2008 R2 only. It does not appear in sys.dm_os_wait_stats on current versions. If you are on a supported version and…

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  • RESOURCE_SEMAPHORE Wait Type in SQL Server

    ⏳Part of the SQL Server Wait Types Library, every wait type explained.Related pillar: Performance & Troubleshooting Queries sit waiting before they even start, CPU is quiet, and RESOURCE_SEMAPHORE is near the top of the waits. Before SQL Server runs a query that sorts or hashes large data sets, it reserves workspace memory for it, called…

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  • RESTORE_MSDA_THREAD_BARRIER Wait Type in SQL Server

    ⏳Part of the SQL Server Wait Types Library, every wait type explained.Related deep dive: BACKUPIO and BACKUPBUFFER Wait TypesRelated pillar: Backup & Recovery Is It a Problem? Routinely, no; it is the coordination cost of restoring from several backup files at once, and its total follows restore duration. It was zero on our SQL Server…

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