Approximate statistical functions
GoogleSQL provides four different approximate aggregate functions which provide better performance on large datasets: APPROX_COUNT_DISTINCT, APPROX_QUANTILES, APPROX_TOP_COUNT, APPROX_TOP_SUM. This exercise will take you through the same query using each function.
This exercise is part of the course
Introduction to BigQuery
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
-- Complete the query to approximate the number of customers that have ordered each product
SELECT
items.product_id,
-- Add the correct syntax for the approximate distinct count
___ AS estimated_unique_customers
FROM ecommerce.ecomm_orders o, UNNEST(o.order_items) items
JOIN ecommerce.ecomm_order_details od USING (order_id)
GROUP BY items.product_id;