CXPACKETTranslation• Contention with queries the at are executing in parallel; across multiple CPUs. Generally due to unbalanced execution across CPUs or tasks ahead of query executing longer than expected.Guideline• >5% for OLTP• >10% for data warehousesResolution• Review indexing• Tune queries• Adjust Max Degree of parallelism• Research cost threshold for parallelism
OLEDBTranslation• Occurs when SQL Server calls the Microsoft SQL Native Client OLE DB Provider. It indicates the duration of calls to the OLE DB provider.Guideline• Examine when it is a top wait and exceeds background waits. (TOP 5)Resolution• Identify queries with OLE DB waits with extended events or sys.dm_os_waiting_tasks• Check application placement and Disk secs/Read and Disk secs/Write• Tune transactions using RPC, Distributed (Linked Server), and Full Text Search
PAGEIOLATCH_xTranslation• Contention caused by disk to memory transfer. Typically suggests disk IO subsystem issues.Guideline• Examine when it is a top wait and exceeds background waits. (TOP 5)Resolution• Review Physical disk: disk seconds/read and Physical disk: disk seconds/write and SQL Server Buffer Manager: Page Life Expectancy• Review information for virtual file stats• Reconfigure disk to improve IO throughput• Analyze indexes to reduce need to move data to memory• Increase memory to increase data available to SQL Server
PAGELATCH_xTranslation• Contention between short term light weight synchronization objects. Latches are not held for the duration of a transaction. Occur in the buffer pool but unrelated to IO requests.Guideline• Examine when it is a top wait and exceeds background waits. (TOP 5)Resolution• Check tempdb configuration • Additional data files • Trace Flag 1118• Troubleshoot memory pressure
LATCH_xTranslation• Contention between short term light weight synchronization objects. Latches are not held for the duration of a transaction. Non buffer pool related.Guideline• Examine when it is a top wait and exceeds background waits. (TOP 5)Resolution• Review T-SQL generating LATCH waits using extended events.• Examine memory items in sys.dm_os_latch_stats• Partition table across multiple files
Additional Resources Waits and Queues • http://is.gd/qWGGnd SQLServerPedia • http://is.gd/gvD80N SQL Server Wait Type • http://is.gd/r59976 Repository Wait Stats Introductory • http://is.gd/khsduZ References Joe Sack • http://is.gd/dQWFwC • http://is.gd/VlH71lManagement Data Warehouse • http://is.gd/xggZSA DMVstats • http://sqldmvstats.codeplex.com
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