Generate a new row for each set of similar rows

[JoeCat]

Essentially creating something of a title row that is ahead of each group of rows. 

The desired outcome would be to create the highlighted rows (that would not currently exist).   I'm having a hard time with Generate rows and my testing is generating MILLIONS of rows so I'm definitely not doing something right.  

I used Multirow formula to created a restarting sequence of numbers each time the "parent commodity clean" changes, starts at 2 and goes up.  So the logic I'd expect would be for any row that has "CommodRow" = 2, create a duplicate of it.

Workflow to play with attached. Thanks in advance.

[binuacs · Accepted solution]

@JoeCat One way of doing this

[Qiu · Accepted solution]

@JoeCat 
We can also go with a bit different approach as below.
Using Unique tool to get identify the first row of every  "parent commodity clean" then Union back to the original data stream.

[flying008]

Hi, @JoeCat 

FYI.

Description	Item Number	Parent Commodity Clean	CommodRow	RowCount
Book item 1	FG006073	Books	2	1
Book item 1	FG006073	Books	2
Book item 2	FG006075	Books	3
Book item 3	FG006130	Books	4
Book item 4	FG006227	Books	5
Games 1	FG001786	Games	2	1
Games 1	FG001786	Games	2
Games 2	FG001828	Games	3
Games 3	FG001902	Games	4
Games 4	FG001904	Games	5
Toys 2	FG001782	Toys	2	1
Toys 2	FG001782	Toys	2
Toys 1	FG003443	Toys	3

[JoeCat]

I like this approach best, very simple and straightfoward.  Thanks!

[JoeCat]

Thanks everyone, I would never thought of unioning data back onto itself.   Also just learned about the Tile tool.  Thank you