Want to know where $post gets saved into database

Hi all. I would like to know the php file where $post and its properties gets saved to the database after the blog gets published.
I am trying to add additional properties to a $post that can be saved. For example one such property is the location the blog was published from. Thank you so much.

I am looking for the PHP file with the sql code that saves $post and its properties. Not looking for the wp_post table in the database. Thank you.