Empty CDF

This query takes time to run

SELECT
customdefinedfield.entitytype,
customdefinedfield.cdf_datatype,
customdefinedfield.name,
cdfvalue.stringvalue,
cdfvalue.numbervalue,
cdfvalue.datevalue,
cdfvalue.organisation_value,
cdfvalue.place_value,
cdfvalue.gazetteer_value,
Count(cdfvalue.cdfvalue_guid)
FROM
cdfvalue
Inner Join customdefinedfield ON customdefinedfield.cdf_id = cdfvalue.cdf_id
WHERE
(cdfvalue.stringvalue IS NULL  OR
cdfvalue.stringvalue =  '') AND
cdfvalue.numbervalue IS NULL  AND
cdfvalue.datevalue IS NULL  AND
cdfvalue.organisation_value IS NULL  AND
cdfvalue.place_value IS NULL  AND
cdfvalue.gazetteer_value IS NULL 
GROUP BY
customdefinedfield.entitytype,
customdefinedfield.cdf_datatype,
customdefinedfield.name,
cdfvalue.stringvalue,
cdfvalue.numbervalue,
cdfvalue.datevalue,
cdfvalue.organisation_value,
cdfvalue.place_value,
cdfvalue.gazetteer_value