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title: Database type and internal DataLens On-premises type mapping table
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  When you create a dataset, DataLens On-premises converts the source data to
  its own type for streamlined data processing. This helps DataLens unify the
  operations with data from different sources.
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# Database type and internal DataLens On-premises type mapping table

When you create a dataset, DataLens converts the source data to its own type for streamlined data processing.
This helps DataLens unify the operations with data from different sources.

The table below shows how data types of different databases and DataLens internal data types map.

DataLens | ClickHouse® | PostgreSQL | YDB
----- | ----- | ----- | -----
**Boolean** | boolean | boolean | boolean
**Date** | date | date | date<br/>date32
**Date and time** | datetime | timestamp | datetime<br/>datetime64<br/>timestamp<br/>timestamp64
**Fractional number** | float<br/>float32<br/>float64<br/>decimal<sup>*</sup> | real<br/>double precision<br/>numeric | float<br/>double<br/>decimal<sup>*</sup><br/>dynumber
**Integer** | integer<br/>int8<br/>int16<br/>int32<br/>int64<br/>uint8<br/>uint16<br/>uint32<br/>uint64 | smallint<br/>integer<br/>bigint | int8<br/>int16<br/>int32<br/>int64<br/>uint8<br/>uint16<br/>uint32<br/>uint64<br/>interval<br/>interval64
**String** | string<br/>enum8<br/>enum16 | char<br/>varchar<br/>text<br/>citext<br/> | string<br/>utf8
**Geopoint** | Set by a formula in DataLens | Set by a formula in DataLens | Set by a formula in DataLens
**Geopolygon** | Set by a formula in DataLens | Set by a formula in DataLens | Set by a formula in DataLens
**Array of integers** | Array(integer)<br/> Array(int8)<br/>Array(int16)<br/>Array(int32)<br/>Array(int64)<br/>Array(uint8)<br/>Array(uint16)<br/>Array(uint32)<br/>Array(uint64) | Array(smallint)<br/>Array(integer)<br/>Array(bigint) | Not supported:
**Float array** | Array(float32)<br/>Array(float64) | Array(real)<br/>Array(double)<br/>Array(precision)<br/>Array(numeric)| Not supported:
**Array of strings** | Array(string) | Array(char)<br/>Array(varchar)<br/>Array(text) | Not supported:

<sup>*</sup> There may be a loss of accuracy when converting data.

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