2021-02-02 12:00:41 +00:00
|
|
|
---
|
|
|
|
|
toc_priority: 191
|
|
|
|
|
---
|
|
|
|
|
|
|
|
|
|
# uniqExact {#agg_function-uniqexact}
|
|
|
|
|
|
2021-03-05 13:14:08 +00:00
|
|
|
计算不同参数值的准确数目。
|
|
|
|
|
|
|
|
|
|
**语法**
|
2021-02-02 12:00:41 +00:00
|
|
|
|
|
|
|
|
``` sql
|
|
|
|
|
uniqExact(x[, ...])
|
|
|
|
|
```
|
2021-03-05 13:14:08 +00:00
|
|
|
如果你绝对需要一个确切的结果，使用 `uniqExact` 函数。 否则使用 [uniq](../../../sql-reference/aggregate-functions/reference/uniq.md#agg_function-uniq) 函数。
|
2021-02-02 12:00:41 +00:00
|
|
|
|
2021-03-05 13:14:08 +00:00
|
|
|
`uniqExact` 函数比 `uniq` 使用更多的内存，因为状态的大小随着不同值的数量的增加而无界增长。
|
2021-02-02 12:00:41 +00:00
|
|
|
|
2021-03-05 13:14:08 +00:00
|
|
|
**参数**
|
2021-02-02 12:00:41 +00:00
|
|
|
|
2021-03-05 13:14:08 +00:00
|
|
|
该函数采用可变数量的参数。 参数可以是 `Tuple`, `Array`, `Date`, `DateTime`, `String`，或数字类型。
|
2021-02-02 12:00:41 +00:00
|
|
|
|
2021-03-05 13:14:08 +00:00
|
|
|
**参见**
|
2021-02-02 12:00:41 +00:00
|
|
|
|
|
|
|
|
- [uniq](../../../sql-reference/aggregate-functions/reference/uniq.md#agg_function-uniq)
|
|
|
|
|
- [uniqCombined](../../../sql-reference/aggregate-functions/reference/uniq.md#agg_function-uniqcombined)
|
|
|
|
|
- [uniqHLL12](../../../sql-reference/aggregate-functions/reference/uniq.md#agg_function-uniqhll12)
|
