@techgirl1908 cool question and I read all the replies, its not my area of expertise. Trying to think of some funky/fun alternative. What about... (cont)
Each user has a "like mask"
Each content has a "like lock"
Give each user a single bit mask field & everytime they like something, update the mask.
Then use the mask over the top of the like lock to see if they have "liked it" in the past.