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 0s.
  • 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.

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 ––

See Also

Data Types



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