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95 lines
3.1 KiB
Markdown
95 lines
3.1 KiB
Markdown
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---
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slug: /en/sql-reference/functions/uniqtheta-functions
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---
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# uniqTheta Functions
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uniqTheta functions work for two uniqThetaSketch objects to do set operation calculations such as ∪ / ∩ / × (union/intersect/not), it is to return a new uniqThetaSketch object contain the result.
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A uniqThetaSketch object is to be constructed by aggregation function uniqTheta with -State.
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UniqThetaSketch is a data structure storage of approximate values set.
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For more information on RoaringBitmap, see: [Theta Sketch Framework](https://datasketches.apache.org/docs/Theta/ThetaSketchFramework.html).
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## uniqThetaUnion
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Two uniqThetaSketch objects to do union calculation(set operation ∪), the result is a new uniqThetaSketch.
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``` sql
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uniqThetaUnion(uniqThetaSketch,uniqThetaSketch)
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```
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**Arguments**
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- `uniqThetaSketch` – uniqThetaSketch object.
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**Example**
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``` sql
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select finalizeAggregation(uniqThetaUnion(a, b)) as a_union_b, finalizeAggregation(a) as a_cardinality, finalizeAggregation(b) as b_cardinality
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from
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(select arrayReduce('uniqThetaState',[1,2]) as a, arrayReduce('uniqThetaState',[2,3,4]) as b );
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```
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``` text
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┌─a_union_b─┬─a_cardinality─┬─b_cardinality─┐
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│ 4 │ 2 │ 3 │
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└───────────┴───────────────┴───────────────┘
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```
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## uniqThetaIntersect
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Two uniqThetaSketch objects to do intersect calculation(set operation ∩), the result is a new uniqThetaSketch.
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``` sql
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uniqThetaIntersect(uniqThetaSketch,uniqThetaSketch)
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```
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**Arguments**
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- `uniqThetaSketch` – uniqThetaSketch object.
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**Example**
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``` sql
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select finalizeAggregation(uniqThetaIntersect(a, b)) as a_intersect_b, finalizeAggregation(a) as a_cardinality, finalizeAggregation(b) as b_cardinality
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from
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(select arrayReduce('uniqThetaState',[1,2]) as a, arrayReduce('uniqThetaState',[2,3,4]) as b );
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```
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``` text
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┌─a_intersect_b─┬─a_cardinality─┬─b_cardinality─┐
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│ 1 │ 2 │ 3 │
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└───────────────┴───────────────┴───────────────┘
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```
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## uniqThetaNot
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Two uniqThetaSketch objects to do a_not_b calculation(set operation ×), the result is a new uniqThetaSketch.
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``` sql
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uniqThetaNot(uniqThetaSketch,uniqThetaSketch)
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```
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**Arguments**
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- `uniqThetaSketch` – uniqThetaSketch object.
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**Example**
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``` sql
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select finalizeAggregation(uniqThetaNot(a, b)) as a_not_b, finalizeAggregation(a) as a_cardinality, finalizeAggregation(b) as b_cardinality
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from
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(select arrayReduce('uniqThetaState',[2,3,4]) as a, arrayReduce('uniqThetaState',[1,2]) as b );
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```
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``` text
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┌─a_not_b─┬─a_cardinality─┬─b_cardinality─┐
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│ 2 │ 3 │ 2 │
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└─────────┴───────────────┴───────────────┘
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```
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**See Also**
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- [uniqThetaSketch](../../sql-reference/aggregate-functions/reference/uniqthetasketch.md#agg_function-uniqthetasketch)
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