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This wait type is when a thread has issued an asynchronous read from a bulk load source file and is waiting for the I/O to complete.
(Books Online description: “Occurs when SQL Server waits for a bulk load I/O to finish.”)
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Added in SQL Server version:
Removed in SQL Server version:
Extended Events wait_type value:
The map_key value in sys.dm_xe_map_values is 149 in 2008 and 2008 R2, and 153 in 2012 and 2014 RTM. After 2014 RTM, you must check the DMV to get the latest value as some map_key values have changed in later builds.
As general guidance for I/O wait types, if the wait time is higher than acceptable I/O latencies for your environment, investigate whether the I/O subsystem is overloaded or has a configuration problem. See the PAGEIOLATCH_SH wait type for more information.
Known occurrences in SQL Server (list number matches call stack list):
- Waiting for a file read to complete during a bulk load
And other similar call stacks.
Abbreviated call stacks (list number matches known occurrences list):