The `DECIMAL`

data type stores exact, fixed-point numbers. This type is used when it is important to preserve exact precision, for example, with monetary data.

## Aliases

In CockroachDB, the following are aliases for `DECIMAL`

:

`DEC`

`NUMERIC`

## Precision and Scale

To limit a decimal column, use `DECIMAL(precision, scale)`

, where `precision`

is the **maximum** count of digits both to the left and right of the decimal point and `scale`

is the **exact** count of digits to the right of the decimal point. The `precision`

must not be smaller than the `scale`

. Also note that using `DECIMAL(precision)`

is equivalent to `DECIMAL(precision, 0)`

.

When inserting a decimal value:

- If digits to the right of the decimal point exceed the column's
`scale`

, CockroachDB rounds to the scale. - If digits to the right of the decimal point are fewer than the column's
`scale`

, CockroachDB pads to the scale with`0`

s. - If digits to the left and right of the decimal point exceed the column's
`precision`

, CockroachDB gives an error. - If the column's
`precision`

and`scale`

are identical, the inserted value must round to less than 1.

## Syntax

A constant value of type `DECIMAL`

can be entered as a numeric literal.
For example: `1.414`

or `-1234`

.

The special IEEE754 values for positive infinity, negative infinity and NaN (Not-a-Number) cannot be entered using numeric literals directly and must be converted using an interpreted literal or an explicit conversion from a string literal instead.

The following values are recognized:

Syntax | Value |
---|---|

`inf` , `infinity` , `+inf` , `+infinity` |
+∞ |

`-inf` , `-infinity` |
-∞ |

`nan` |
NaN (Not-a-Number) |

For example:

`DECIMAL '+Inf'`

`'-Inf'::DECIMAL`

`CAST('NaN' AS DECIMAL)`

## Size

The size of a `DECIMAL`

value is variable, starting at 9 bytes. It's recommended to keep values under 64 kilobytes to ensure performance. Above that threshold, write amplification and other considerations may cause significant performance degradation.

## Examples

```
> CREATE TABLE decimals (a DECIMAL PRIMARY KEY, b DECIMAL(10,5), c NUMERIC);
> SHOW COLUMNS FROM decimals;
```

```
+-------+---------------+-------+---------+
| Field | Type | Null | Default |
+-------+---------------+-------+---------+
| a | DECIMAL | false | NULL |
| b | DECIMAL(10,5) | true | NULL |
| c | DECIMAL | true | NULL |
+-------+---------------+-------+---------+
```

```
> INSERT INTO decimals VALUES (1.01234567890123456789, 1.01234567890123456789, 1.01234567890123456789);
> SELECT * FROM decimals;
```

```
+------------------------+---------+-----------------------+
| a | b | c |
+------------------------+---------+-----------------------+
| 1.01234567890123456789 | 1.01235 | 1.0123456789012346789 |
+------------------------+---------+-----------------------+
# The value in "a" matches what was inserted exactly.
# The value in "b" has been rounded to the column's scale.
# The value in "c" is handled like "a" because NUMERIC is an alias.
```

## Supported Casting & Conversion

`DECIMAL`

values can be cast to any of the following data types:

Type | Details |
---|---|

`INT` |
Truncates decimal precision |

`FLOAT` |
Loses precision and may round up to +/- infinity if the value is too large in magnitude, or to +/-0 if the value is too small in magnitude |

`BOOL` |
0 converts to `false` ; all other values convert to `true` |

`STRING` |
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