Reducing model size by 83% (Patrick / GIAC) -- how??

[SergiiR]

Hi, wizards 😃

Recently I watched a life-hack video from Patrick LeBlanc (from Guy in a Cube) on model size optimization. He reduced size of the model by 83% with no touching of granularity. ...  ............ ??

I remember watching another video from another Whale of Power BI data modeling -- Alberto Ferrari (from SQLBI) on the similar topic... yet he mentioned that no significant difference was found in changing data type from date to integer or back.

I really cannot get what's the trick behind Patrick's optimization, but as you can see on the scheme below, he really didn't touch the granularity. Yet he did split the datetime column to date and time columns (on this stage he received no significant impact) and created Dim Tables for them, using Surrogate Keys with the data type of integer (this was the stage where the model size collapsed)

So my question is how is this possible?... what was the reason for model size collapsing? 

Thanks in advance for any hints and explanations!

[SergiiR]

@amitchandak 
Thanks for your suggestion, yet it was not the case in this particular issue. There is a link to the video in the initial message, you can observe all steps that were done by Patrick.... 

Yet thanks again for suggestion!

[amitchandak]

@SergiiR , Can you also disable auto date hierarchy and check