I've had this happen a few times. What is the max pool size in your MSSQL config? Ours ended up set to 1 at some point, and I'd get that error whenever two queries occur at the same time. I bumped it to 5 and the issue went away.
I am thinking that if
- [sampleDB].[dbo].[sampleTable] having less than 20 rows.
Stored Procedure returning result in less than 2 or 3 seconds and It returns 1 row and 3 column.
There is something not quite right. We have a similar./lower spec SQL server (12 Core/6gb ram) on our network, and can easily run far more complicated queries that amount of time. Sounds like the server is being hammered, or has a config issue.
Other things to try:
Bump the timeout to 60s say, just to see if the query ever does return.
Change it to a query directly in the SQL node, rather than a stored procedure.
Run the query a bunch of times in MSSQL Management Studio, see if it ever happens there.