My first guess is that if you always store the full string you don't need to scan the database to see if you already have the same string. Essentially you choos

My first guess is that if you always store the full string you don't need to scan the database to see if you already have the same string. Essentially you choose to use more space but reduce load. Regardless of whether you do the string deduping on inserts or async later on, you have to do it at some point and the unpredictable performance overhead might be undesirable.