Option 1 (Single group by query) select c.cid,c.title,c.body,coalsece(sum(r.score),0) as score from comments c left outer join comment_ratings r on c.cid = r.cid group by c.cid,c.title,c.body;
Option 2 (Two simple queries) select cid,title,body from comments; select cid,sum(score) from comment_ratings;
I know that in general you always want to keep the number of queries to a minimum and that Option 1 is the most logical/preferred way to proceed. However, I've greatly simplified Option 1. In practice I'm going to be pulling a lot more columns and will be inner joining to additional tables. So my real question is whether having a lot of items in the group by clause will have an adverse effect on performance.