quantile - 高效使用 BigQuery 的 APPROX_QUANTILES

Question

现在，如果我想获得某个值的十分位数，我会这样做

SELECT
    APPROX_QUANTILES(value, 100)[SAFE_ORDINAL(10)] as p10,
    APPROX_QUANTILES(value, 100)[SAFE_ORDINAL(20)] as p20,
    APPROX_QUANTILES(value, 100)[SAFE_ORDINAL(30)] as p30,
    APPROX_QUANTILES(value, 100)[SAFE_ORDINAL(40)] as p40,
    APPROX_QUANTILES(value, 100)[SAFE_ORDINAL(50)] as p50,
    APPROX_QUANTILES(value, 100)[SAFE_ORDINAL(60)] as p60,
    APPROX_QUANTILES(value, 100)[SAFE_ORDINAL(70)] as p70,
    APPROX_QUANTILES(value, 100)[SAFE_ORDINAL(80)] as p80,
    APPROX_QUANTILES(value, 100)[SAFE_ORDINAL(90)] as p90,
    APPROX_QUANTILES(value, 100)[SAFE_ORDINAL(100)] as p100
FROM table

我想确保这不会使大型查询的工作量增加 10 倍，并且是否有更紧凑的方式来编写此内容

Answer 1

如果您运行查询，然后检查执行计划，您将看到 BigQuery 仅计算一次分位数，然后在第二步中提取数组的各个元素。您无需担心自己尝试对 APPROX_QUANTILES 聚合进行重复数据删除。