What is SQL Server Launchpad Service? – Interview Question of the Week #168

Question: What is the SQL Server Launchpad service?

Answer: A reader once emailed me a screenshot of Windows Services and asked about the SQL Server Launchpad entries. I was stumped for a moment. I know a great deal about SQL Server, but not every optional Windows service is part of an ordinary database installation. That question made a useful interview answer.

Launchpad is part of SQL Server’s extensibility framework. When Machine Learning Services is installed for an instance, the database engine uses that instance’s Launchpad service to start supported external-language work, such as R and Python, in separate processes. Launchpad is not a second SQL Server engine, and finding it in Services doesn’t mean that every application query runs through it.

If you’re only trying to identify the service, don’t change a server setting. First look in SQL Server Configuration Manager for the Launchpad service belonging to that instance. Then inspect whether external scripts are enabled:

EXEC sys.sp_configure N'external scripts enabled';

For an installation that intentionally runs external scripts, an administrator must install the supported feature, enable the configuration, and restart the required service before testing a language runtime. Here is the setting. It’s a configuration step, not something to run because a Launchpad entry appears:

-- Administrator action only when Machine Learning Services is intended.
EXEC sys.sp_configure N'external scripts enabled', 1;
RECONFIGURE;

Turning off or stopping Launchpad affects external-script execution for that instance, not normal T-SQL queries. I still appreciate the reader who sent the screenshot; it reminded me that a good question can start with admitting what I need to look up.

Launchpad is not a second SQL Server, it is the doorway for R and Python scripts, and plain T-SQL never walks through it.

Published by Pinal Dave on SQLAuthority. More of my work at pinaldave.com.