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  DataLens On-premises error
  ERR.DS_API.DB.INVALID_FUNCTION.PG_DOUBLE_PRECISION_ROUND
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  This page describes the ROUND with precision parameter is not supported for
  double precision data type in PostgreSQL DataLens On-premises error.
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---

# [DataLens On-premises] ROUND with precision parameter is not supported for double precision data type in PostgreSQL

`ERR.DS_API.DB.INVALID_FUNCTION.PG_DOUBLE_PRECISION_ROUND`

The [ROUND](../..//function-ref/ROUND.md) function with the `precision` parameter is not supported for the `double precision` type of PostgreSQL data source.

DataLens recognizes PostgreSQL's `double precision` and `numeric` types as a `Fractional number`. Out of these two types, the ROUND function with the `precision` parameter only supports `numeric`. To get `double precision` back to the database level, use another function: [DB_CAST](../..//function-ref/DB_CAST.md).

Here is an example:

```
ROUND(DB_CAST([your field]/1000000, 'numeric', 16, 8) [, precision ]), where 16 is the total number of digits in the fractional number, and 8 is its count of decimal places.
```