cf_stats_errors.sql

WITH error_stats AS (
  SELECT 
    labels.execution_id as execution_id
    , MIN(resource.labels.function_name) as name
    , MAX(IF(severity="ERROR", 1, 0)) as error
  FROM `<dataset_id>.logging.cloudfunctions_googleapis_com_cloud_functions_*`
  WHERE _TABLE_SUFFIX BETWEEN '20190101' AND '20190315'
  GROUP BY labels.execution_id
)
SELECT 
   name
   , ROUND((SUM(error)/COUNT(error)), 2) as proportion_with_errors
FROM error_stats
GROUP BY name
ORDER BY proportion_with_errors DESC