I've been thinking on how to store data efficiently in database tables, I'll give the examples in visual look. See pictures below.
I've come to think to store data in database using compressed values row with the thinking of to save a lot of rows to remove duplicate page_id's
The other one is the usual that I've seen, I separate row_id's per page_id's.
The one I'm concerned is, which is the best way or am I doing it wrong on my first way storing data.