WiX e .msp identify if it requires update by (fileexists)

Question

I'm still new to the WiX world, this week I discovered the .msp extension used for updating.

I would like to know if I can identify a possible update through (fileexists)

Why that? So I wouldn't have to run the MSI on past machines, only to be able to run the MSP later.

Or if there is any way to start the .msp without having run the .msi before.

Thank you!

Answer 1

Patches don't work that way. To get what you want, use major upgrades -- they work for initial install and later updates. As I said at https://www.joyofsetup.com/2008/12/29/neither-more-nor-less/:

Major upgrades aren’t so limited: They can change anything in a product, but also support as few changes as a small update. So even if you’re changing only a few files, you can still use major upgrades. Think of major as an upper limit on the set of changes, not the lower limit on the type of upgrade you need.