How to search for msgs that include a string

my model is Video {videoId, comments [[ 60 messages], [ 60 messages], [ 60 messages], [ 60 messages]] it used to be Video{videoId, comments[ message {}, message {}. message {}, ] the first method has 1000 arrays of 60 messages the second method has 1 array of 60k messages i did this to avoid max array size is this better? if it is how can i query arrays of arrays i want to search for msgs that have the same contentOffsetSecond and include 'lol' somewhere in the msg