Chasing SSAS Connection Timeouts

Suppose you have a Tabular model and you send a massive DAX query to it that could run for hours, such as to calculate many measures (in our case hundreds) for each customer overnight so that you can cache the results and delight the user with super-fast lookups. This issue could also apply to Multidimensional although in this case Tabular was used. The server times out sporadically the query after a random execution time. You have changed all possible connection timeout options (SSAS ServerTimeout, SSIS connection timeout, etc.) to no avail. In fact, if you have scheduled an Agent job that calls an SSIS package that executes the query, the package doesn’t register the exception and continues executing indefinitely, but a Profiler trace (or XEvents session) shows that the server raises a Connection Timeout error.

How to fix this horrible issue? Change the two undocumented settings in the MSMDSRV.INI file from 60,000 to 600,000.

<ServerSendTimeout>600000</ServerSendTimeout>

<ServerReceiveTimeout>600000</ServerReceiveTimeout>