How to run a long query from a trigger without upset I have some log records that are inserted into a table in my database. When they land, I would like to process them asap. The processing could potentially be a bit lengthy.

I would just write a trigger to do the processing, but I'm worried it will cause problems if it takes a while.

Is there a way to call a stored procedure asynchronously from a trigger? Or perhaps a better way of doing this altogether?
I would recommend you to use "SQL Server Service Broker". It allow you to run queries asynchronously not only in triggers.

Here is the link to documentation: https://msdn.microsoft.com/en-us/library/bb522893.aspx

Here is a link to a tutorial that works through how to set this up: http://www.sqlservercentral.com/articles/Service+Broker/73398/