The intermediate state of an aggregate function. To get it, use aggregate functions with the `-State` suffix. To get aggregated data in the future, you must use the same aggregate functions with the `-Merge`suffix.
`AggregateFunction` — parametric data type.
**Parameters**
- Name of the aggregate function.
If the function is parametric specify its parameters too.
[uniq](../../query_language/agg_functions/reference.md#agg_function-uniq), anyIf ([any](../../query_language/agg_functions/reference.md#agg_function-any)+[If](../../query_language/agg_functions/combinators.md#agg-functions-combinator-if)) and [quantiles](../../query_language/agg_functions/reference.md) are the aggregate functions supported in ClickHouse.
To insert data, use `INSERT SELECT` with aggregate `-State`- functions.
**Function examples**
```
uniqState(UserID)
quantilesState(0.5, 0.9)(SendTiming)
```
In contrast to the corresponding functions `uniq` and `quantiles`, `-State`- functions return the state, instead the final value. In other words, they return a value of `AggregateFunction` type.
In the results of `SELECT` query the values of `AggregateFunction` type have implementation-specific binary representation for all of the ClickHouse output formats. If dump data into, for example, `TabSeparated` format with `SELECT` query then this dump can be loaded back using `INSERT` query.
When selecting data from `AggregatingMergeTree` table, use `GROUP BY` clause and the same aggregate functions as when inserting data, but using `-Merge`suffix.
An aggregate function with `-Merge` suffix takes a set of states, combines them, and returns the result of complete data aggregation.
For example, the following two queries return the same result:
```sql
SELECT uniq(UserID) FROM table
SELECT uniqMerge(state) FROM (SELECT uniqState(UserID) AS state FROM table GROUP BY RegionID)
