A SQL query searching for rows that satisfy Column1 <= X <= Column2 is very slow

Question

I am using a MySQL DB, and have the following table:

CREATE TABLE SomeTable (
  PrimaryKeyCol BIGINT(20) NOT NULL,
  A BIGINT(20) NOT NULL,
  FirstX INT(11) N         


        

Answer 1

Another approach is to precalculate the solutions, if that number isn't too big.

CREATE TABLE SomeTableLookUp (
    X INT NOT NULL
    PrimaryKeyCol BIGINT NOT NULL,
    PRIMARY KEY(X, PrimaryKeyCol)
);

And now you just pre-populate your constant table.

INSERT INTO SomeTableLookUp
SELECT X, PrimaryKeyCol
FROM SomeTable
JOIN (
   SELECT DISTINCT X FROM SomeTable 
) XS
WHERE XS.X BETWEEN StartX AND EndX 

And now you can SELECT your answers directly.

SELECT SomeTable.*
FROM SomeTableLookup
JOIN SomeTable
ON SomeTableLookup.PrimaryKeyCol = SomeTable.PrimaryKeyCol
WHERE SomeTableLookup = ?
LIMIT 10