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I have a poorly written application running a SELECT *, resulting in a 2MB result set every few seconds. I cannot correct this. I am confused though,by the connection encountering ASYNC_NETWORK_IO waits. The application is local to the database server.

I have verified the session_id in dm_exec_connections is 'Shared memory'. The client_net_address is 'local machine'.

Anyone ever experienced this before? Or able to explain to me why this is happening?


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up vote 3 down vote accepted

ASYNC_NETWORK_IO also happens when the app is NOT reading the data fast enough from SQL Server. Note that this is NOT SQL Server issue but its the app issue. Make sure the app is reading the data as a set instead of row by row.

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Thank you. Unfortunately, there is nothing I can do to resolve the application code. I was more curious as to why this wait type would be showing up under these circumstances. – Kenneth May 18 '11 at 13:07

Even though the application is local, the communication will happen using the networking protocols. Hence, slower data transfer will still show up as ASYNC_NETWORK_IO even on the local machine.

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