I have an app that is displaying metrics about defects in a project.

I have the option of making one query that returns all the defects, and from that I can break out about four different metrics (How many defects escaped QA in 90 days, 180 days, and then the same metrics again but only counting sev1/sev2 defects).

I could make four queries and limit the results to one so that I just get a count for each. Or I could make one query that encompass them all (all defects that escaped QA in 180 days) and then count up the difference.

I'm figuring worst case, the number of defects that escaped QA in the last six months will generally be less than 100, certainly less 500 worst case.

Which would you do-- four queryies with one result each, or one single query that on average might return 50, perhaps worst case 500?

And I guess the key question is-- where are the inflections points? Perhaps I have more metrics tomorrow (who knows, 8?) and a different average defect counts. Is there a rule of thumb I could use to help choose which approach?