Optimaliseer MySQL-query's met veel LEFT JOINs en GROUP BY

Minimumindexen ::

    CREATE INDEX a0 ON a (col4, col5) ;
    CREATE INDEX a1 ON a (col3) ;
    CREATE INDEX a2 ON a (col4) ;

    CREATE INDEX b1 ON b (col1) ;
    CREATE INDEX b2 ON b (col3) ;

    CREATE INDEX c1 ON c (col1) ;

    CREATE INDEX d1 ON d (col2) ;

U kunt ook maken,

    CREATE INDEX e1 ON e (col1) ;

    CREATE INDEX a4 ON a (col1) ;