September 14, 2011 at 11:25 pm
I'm running SQL 2005, sp2, 32 Bit OS with 3/gb + awe. (7gb ram). CPU 2 <- THis is all on vsphere.
My table has 87 columns , a bunch of floats, nvarchar and 4 ntext and 1 image.
The table of 32k rows equates to around 400mb.
when I query the table I see a waiting tasks alternating between ASYNC_NETWORK_IO.
It's a table, not a view, there are no functions or anything that would require networking.
The select runs anything between 30-90 seconds to return all rows.
Does anyone have an idea why I see network waits ?
There is no other activity on the db.
I'm just wondering if the blob stuff makes use of named pipes \ tcpip. I even see that network waits if I am on the local box.
September 14, 2011 at 11:37 pm
I think I just answered my own question but it would be helpful if someone could verify.
It would appear that the waiting I'm seeing is for SQL to return the data to the result set. WHether I'm local or remote this shouldn't matter because I'm getting the data one way or the other?
So the next assumption would be that if I do a count(1) I shouldn't see the network IO ( tested this and I can't see anything but the query finish to quick).
What I didn't know is that I would see ASYNC_NETWORK_IO, I don't believe this would be the case for results to be displayed. I'd assume as per the name the partner would have to participate in the transaction reading or writing.
September 15, 2011 at 7:48 am
The ASYNC_NETWORK_IO wait type is associated with either a calling application that is not processing results quickly enough from SQL Server or is associated with a network performance issue.
Thanks
Chris
September 15, 2011 at 10:35 am
Can you try the query omitting the BLOB data types (ntext, image)? BLOB data types really slow down queries when you return them. I don't know if that would cause ASYNC_NETWORK_IO waits, but it might. So I'd start with this and then see what else is happening.
Jack Corbett
Consultant - Straight Path Solutions
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