to_quantile_state

Description

此函数将数值类型转化成 QUANTILE_STATE 类型。 compression 参数是可选项，可设置范围是[2048, 10000]，值越大，后续分位数近似计算的精度越高，内存消耗越大，计算耗时越长。 compression 参数未指定或设置的值在[2048, 10000]范围外，以 2048 的默认值运行

Syntax

TO_QUANTILE_STATE(<raw_data> <compression>)

Parameters

参数	描述
<raw_data>	目标列。
<compression>	压缩阈值。

Return value

转换之后的 QUANTILE_STATE 类型的列。

Example

CREATE TABLE IF NOT EXISTS ${tableName_21} (
         `dt` int(11) NULL COMMENT "",
         `id` int(11) NULL COMMENT "",
         `price` quantile_state QUANTILE_UNION NOT NULL COMMENT ""
        ) ENGINE=OLAP
        AGGREGATE KEY(`dt`, `id`)
        COMMENT "OLAP"
        DISTRIBUTED BY HASH(`dt`) BUCKETS 1
        PROPERTIES ("replication_num" = "1");

INSERT INTO quantile_state_agg_test VALUES(20220201,0, to_quantile_state(1, 2048));

INSERT INTO quantile_state_agg_test VALUES(20220201,1, to_quantile_state(-1, 2048)),
            (20220201,1, to_quantile_state(0, 2048)),(20220201,1, to_quantile_state(1, 2048)),
            (20220201,1, to_quantile_state(2, 2048)),(20220201,1, to_quantile_state(3, 2048));

SELECT dt, id, quantile_percent(quantile_union(price), 0) FROM quantile_state_agg_test GROUP BY dt, id ORDER BY dt, id

结果为

+----------+------+--------------------------------------------+
| dt       | id   | quantile_percent(quantile_union(price), 0) |
+----------+------+--------------------------------------------+
| 20220201 |    0 |                                          1 |
| 20220201 |    1 |                                         -1 |
+----------+------+--------------------------------------------+