In PostgreSQL, the scale() function returns the scale of its argument.

The scale is the number of decimal digits in the fractional part.

Syntax

The syntax goes like this:

scale(numeric)

Where numeric is the number for which you want the scale returned.

Example

Here’s an example of how it works.

SELECT scale(0.1234);

Result:

4

Here are some more.

SELECT 
  scale(0) AS "0",
  scale(0.1) AS "0.1",
  scale(0.12) AS "0.12",
  scale(0.123456789) AS "0.123456789";

Result:

 0 | 0.1 | 0.12 | 0.123456789
---+-----+------+-------------
 0 |   1 |    2 |           9

Negative Numbers

It works on negative numbers just the same.

SELECT 
  scale(0) AS "0",
  scale(-0.1) AS "-0.1",
  scale(-0.12) AS "-0.12",
  scale(-0.123456789) AS "-0.123456789";

Result:

 0 | -0.1 | -0.12 | -0.123456789
---+------+-------+--------------
 0 |    1 |     2 |            9

Expressions

You can also provide expressions, such as the following.

SELECT 
  1.23 * 0.3 AS "Result of expression",
  scale(1.23 * 0.3);

Result:

 Result of expression | scale
----------------------+-------
                0.369 | 3