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40 lines
1.6 KiB
Markdown
40 lines
1.6 KiB
Markdown
---
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sidebar_position: 195
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---
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# uniqTheta {#agg_function-uniqthetasketch}
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Calculates the approximate number of different argument values, using the [Theta Sketch Framework](https://datasketches.apache.org/docs/Theta/ThetaSketchFramework.html).
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``` sql
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uniqTheta(x[, ...])
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```
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**Arguments**
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The function takes a variable number of parameters. Parameters can be `Tuple`, `Array`, `Date`, `DateTime`, `String`, or numeric types.
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**Returned value**
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- A [UInt64](../../../sql-reference/data-types/int-uint.md)-type number.
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**Implementation details**
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Function:
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- Calculates a hash for all parameters in the aggregate, then uses it in calculations.
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- Uses the [KMV](https://datasketches.apache.org/docs/Theta/InverseEstimate.html) algorithm to approximate the number of different argument values.
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4096(2^12) 64-bit sketch are used. The size of the state is about 41 KB.
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- The relative error is 3.125% (95% confidence), see the [relative error table](https://datasketches.apache.org/docs/Theta/ThetaErrorTable.html) for detail.
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**See Also**
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- [uniq](../../../sql-reference/aggregate-functions/reference/uniq.md#agg_function-uniq)
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- [uniqCombined](../../../sql-reference/aggregate-functions/reference/uniqcombined.md#agg_function-uniqcombined)
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- [uniqCombined64](../../../sql-reference/aggregate-functions/reference/uniqcombined64.md#agg_function-uniqcombined64)
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- [uniqHLL12](../../../sql-reference/aggregate-functions/reference/uniqhll12.md#agg_function-uniqhll12)
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- [uniqExact](../../../sql-reference/aggregate-functions/reference/uniqexact.md#agg_function-uniqexact)
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