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Tableau won't create virtual rows for you, but you can generate the structure you want very easily from a couple of tables structured like this:
ID Start End ID1 January 2007 October 2015 ID2 January 2009 December 2020 ... Month Offset 0 1 2 3 4 5 ...
You just need a custom SQL connection something like this (except that you will need to replace the red date functions with the correct functions for your datasource, as explained below):
DATEADD('month', [Offsets].[Month Offset], [DateRanges].[Start Date])
FROM [DateRanges], [Offsets]
WHERE [Offsets].[Month Offset] <= DATEDIFF('month', [DateRanges].[Start Date], [DateRanges].[End Date])
The syntax of the date functions varies a lot for different database back-ends, so you'll need to find the right functions for your database. The easiest way to do that can be to generate a Tableau calculated field which does the date calculation you want just on some dummy data and then look in the Tableau logs to see what SQL that generates for your database.