Use google bigquery to build histogram graph

Question

How can write a query that makes histogram graph rendering easier?

For example, we have 100 million people with ages, we want to draw the histogram/buckets for age 0

Answer 1

With #standardSQL and an auxiliary stats query, we can define the range the histogram should look into.

Here for the time to fly between SFO and JFK - with 10 buckets:

WITH data AS ( 
    SELECT *, ActualElapsedTime datapoint
    FROM `fh-bigquery.flights.ontime_201903`
    WHERE FlightDate_year = "2018-01-01" 
    AND Origin = 'SFO' AND Dest = 'JFK'
)
, stats AS (
  SELECT min+step*i min, min+step*(i+1)max
  FROM (
    SELECT max-min diff, min, max, (max-min)/10 step, GENERATE_ARRAY(0, 10, 1) i
    FROM (
      SELECT MIN(datapoint) min, MAX(datapoint) max
      FROM data
    )
  ), UNNEST(i) i
)

SELECT COUNT(*) count, (min+max)/2 avg
FROM data 
JOIN stats
ON data.datapoint >= stats.min AND data.datapoint

If you need round numbers, see: https://stackoverflow.com/a/60159876/132438