Mysql count performance on very big tables

Question

I have a table with more than 100 millions rows in Innodb.

I have to know if there is more than 5000 rows where the foreign key = 1. I don\'t need the exact number.<

Answer 1

You don't seem interested in the actual count so give this a try:

SELECT 1 FROM table WHERE fk = 1 LIMIT 5000, 1

If a row is returned, you have 5000 and more records. I presume the fk column is indexed.