In PostgreSQL, the isfinite() function tests for a finite date, timestamp or interval.
This can be useful, because Postgres supports infinite dates/timestamps. For example, you could have a timestamp of infinity or negative infinity, and this function allows you to test for that.
In PostgreSQL, the pg_typeof() function allows you to get the data type of any value.
More specifically, it returns the OID of the data type of the value that is passed to it. It returns a regtype, which is an OID alias type. Therefore it’s the same as an OID for comparison purposes but displays as a type name.
In PostgreSQL, the div() function returns the integer quotient of its first argument divided by its second argument.
In PostgreSQL, the power() function returns its first argument raised to the power of its second argument.
In PostgreSQL, the scale() function returns the scale of its argument.
The scale is the number of decimal digits in the fractional part.
In PostgreSQL, the sign() function is used to indicate the sign of its argument.
It doesn’t simply return the actual sign. Rather, it returns -1 for negative numbers, 0 for zero, and 1 for positive numbers.
In PostgreSQL, clock_timestamp() is a non-SQL-standard time function that returns the current date and time.
An important consideration of this function is that its result changes throughout the execution of a statement. Therefore, you could get a different result in different parts of the statement if you call the function multiple times within a single statement.
In PostgreSQL, the cbrt() function returns the cube root of its argument.
The cube root of a number x is a number y such that y3 = x.
In PostgreSQL, the sqrt() function returns the square root of its argument.
The square root of a number x is the number y such that y2 = x.
In PostgreSQL, the abs() function returns the absolute value of its argument.
The absolute value means how far the number is away from zero. Therefore, the absolute value of 7 is 7, and the absolute value of -7 is also 7.
Therefore, any negative values passed to abs() are returned as positive values. Positive values and zero are returned unchanged.