MySQL Enhancing Performance without Cache

Question

I am using MySQL version 5.5.14 to run the following query from a table of 5 Million rows:

SELECT P.ID, P.Type, P.Name, P.cty
     , X(P.latlng) as \'lat\', Y(P.         


        

Answer 1

Good indexes are the ones with high selectivity. Your conditions are mostly range conditions and this poses a limit on the fields that can be used in a composite index.

Possible indexes to investigate (composed from those fields that have an equality check with the addition in the end, of one field with a range check):

(act, Type, tn, flA)

(act, Type, tn, cDate)

(act, Type, tn, nb)

To check selectivity without creating indexes, you could use:

SELECT COUNT(*)
FROM PIG P 
WHERE act='1' 
  AND Type = 'g' 
  AND tn = 'l' 
  AND flA >= '1615'

and

SELECT COUNT(*)
FROM PIG P 
WHERE act='1' 
  AND Type = 'g' 
  AND tn = 'l' 
  AND cDate >= NOW() 

and

SELECT COUNT(*)
FROM PIG P 
WHERE act='1' 
  AND Type = 'g' 
  AND tn = 'l' 
  AND nb <= '5' 

and compare the output with the 742873 you have from the spatial index.