For each query I had to optimize, I wrote dozens, if not hundreds, that worked without any intervention. 99% is just a rough guess. > If you have a query that

For each query I had to optimize, I wrote dozens, if not hundreds, that worked without any intervention. 99% is just a rough guess. > If you have a query that needs to look at over about 5K rows and you need responses under 100ms you need to know what its doing. Thats very unspecific, but getting 5000 rows from a table should take a few milliseconds on modern hardware.