Our friends with WiX (principally bloggers Rob Mensching and Heath Stewart) had some questions about the schema changes.  One of those questions was:

Question:
Did you really mean to build a patching feature that we can't patch to because of a schema change?

Context:

Windows Installer 4.5 supports adding a custom action that will run during patch uninstall.  For beta, this was accomplished by adding a new bit msidbCustomActionTypePatchUninstall to the CustomAction table.  Given the value of the bit msidbCustomActionTypePatchUninstall is 0x8000, it means the schema for the Type column of the CustomAction table changes from i2 (the integer column data type) to i4 (the double integer column data type)

Answer:

Thanks for bringing this to our attention.  No, this was not our intent.  As I recall, the change from an attribute bit in the i2 range to the upper half of the i4 range was a side effect from a bug fix.

Thanks for the suggestions to have a separate table or an separate "Ex" column in the same table.  These are both quality ideas for enabling supporting patching in this patching feature. 

Development is considering this feedback and is formulating their solution.

[Author: Robert Flaming]
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