Question

so I have the following query:

SELECT DISTINCT d.iID1 as 'id',
                      SUM(d.sum + d.count*r.lp)/sum(d.count) AS avgrat
                      FROM abcd i, abce r, abcf d
                      WHERE r.aID = 1 AND
                      d.iID1 <> r.rID  AND d.iID2 = r.rID GROUP BY d.iID1
                      ORDER BY avgrat LIMIT 50;

the problem is….with millions of entries in the table, SUM() and GROUP BY would freeze up the query….is there a way to do exactly this that would execute instantaneously using MySQL and/or PHP hacks (perhaps do the summing with PHP….but how would I go about doing that…)

Answer 1

To answer the direct question: no, there is no way to do anything instantaneously.

If you have control over the table updates, or the application which adds the relevant records, then you could add logic which updates another table with the sum, count, and id with each update. Then a revised query targets the “sum table” and trivially calculates the averages.