uniqTheta 函数

uniqTheta 函数用于两个 uniqThetaSketch 对象之间进行集合操作计算，例如 ∪ / ∩ / ×（并集/交集/差集），返回一个新的 uniqThetaSketch 对象，其中包含结果。

uniqThetaSketch 对象通过聚合函数 uniqTheta 构造，使用 -State。

UniqThetaSketch 是一种存储近似值集合的数据结构。 有关 RoaringBitmap 的更多信息，请参阅：Theta Sketch Framework。

uniqThetaUnion

两个 uniqThetaSketch 对象进行并集计算（集合操作 ∪），结果是一个新的 uniqThetaSketch。

uniqThetaUnion(uniqThetaSketch,uniqThetaSketch)

参数

• uniqThetaSketch – uniqThetaSketch 对象。

示例

SELECT finalizeAggregation(uniqThetaUnion(a, b)) AS a_union_b, finalizeAggregation(a) AS a_cardinality, finalizeAggregation(b) AS b_cardinality
FROM
(SELECT arrayReduce('uniqThetaState',[1,2]) AS a, arrayReduce('uniqThetaState',[2,3,4]) AS b );

┌─a_union_b─┬─a_cardinality─┬─b_cardinality─┐
│         4 │             2 │             3 │
└───────────┴───────────────┴───────────────┘

uniqThetaIntersect

两个 uniqThetaSketch 对象进行交集计算（集合操作 ∩），结果是一个新的 uniqThetaSketch。

uniqThetaIntersect(uniqThetaSketch,uniqThetaSketch)

参数

• uniqThetaSketch – uniqThetaSketch 对象。

示例

SELECT finalizeAggregation(uniqThetaIntersect(a, b)) AS a_intersect_b, finalizeAggregation(a) AS a_cardinality, finalizeAggregation(b) AS b_cardinality
FROM
(SELECT arrayReduce('uniqThetaState',[1,2]) AS a, arrayReduce('uniqThetaState',[2,3,4]) AS b );

┌─a_intersect_b─┬─a_cardinality─┬─b_cardinality─┐
│             1 │             2 │             3 │
└───────────────┴───────────────┴───────────────┘

uniqThetaNot

两个 uniqThetaSketch 对象进行 a_not_b 计算（集合操作 ×），结果是一个新的 uniqThetaSketch。

uniqThetaNot(uniqThetaSketch,uniqThetaSketch)

参数

• uniqThetaSketch – uniqThetaSketch 对象。

示例

SELECT finalizeAggregation(uniqThetaNot(a, b)) AS a_not_b, finalizeAggregation(a) AS a_cardinality, finalizeAggregation(b) AS b_cardinality
FROM
(SELECT arrayReduce('uniqThetaState',[2,3,4]) AS a, arrayReduce('uniqThetaState',[1,2]) AS b );

┌─a_not_b─┬─a_cardinality─┬─b_cardinality─┐
│       2 │             3 │             2 │
└─────────┴───────────────┴───────────────┘

另见

• uniqThetaSketch