Mysql - Aggregate function is very slow

Question

I have a mysql database with very large tables. I often run queries that involve aggregate functions. Queries with the aggregate functions like MIN, MAX, SUM, COUNT are running very slow. Please help me to increase the speed.

SELECT MIN(PeriodTime) FROM ResultsTable WHERE (OrderId=271)
SELECT COUNT(*) FROM ResultsTable WHERE (OrderId=271);  ==> returns 258021

Total rows in that table = 1213284, My Query matches = 258021 rows.

I appreciate any help. Thank you.

Answer 1

Create an index on ResultsTable that covers PeriodTime and OrderId. That will help a lot.