Sql - postgres - Arbitrary precision :: numeric

From the Postgres manual we can see that the numeric has precision of:

  

131072 digits before decimal point
  16383 digits after the decimal point

This is the default value, however it is possible to set this pattern with:

numeric(num1, num2)

In which num1 is the precision, ie how many digits do I want to have my numeric. And num2 is how many decimals it should have.

It should be noted that num2 uses the definition of num1 that is, it is not a sum of digits, is the use of it, eg:

EX1 : numeric(12,2) // estou dizendo que terei 12 digitos, sendo 2 decimais.
EX2 : numeric(8,6)  // estou dizendo que terei 8 digitos, sendo 6 decimais.

In this situation my EX1 bears 9.999.999.999,99 . While EX2 can not exceed 99,999999 ; because I defined a total of 8 digits being 6 decimals.

Analogy

subtracting num2 from num1 we will have the number of decimals supported in our column.