approx_count_distinct
function approx_count_distinct($1) returns bigint
approx_quantiles
function approx_quantiles($1, bigint) returns array<$1>
approx_top_count
function approx_top_count($1, bigint) returns array<struct<value $1, count bigint>>
approx_top_sum
function approx_top_sum($1, bigint, bigint) returns array<struct<value $1, sum $1>>