1.1. Numeric Types

Numeric types consist of two-, four-, and eight-byte integers, as well as eight-byte floating-point numbers and selectable-precision decimals. Table 1.2 lists the available types.

Table 1.2. Numeric Types

NameStorage SizeDescriptionRange
smallint2 bytessmall-range integer-32768 to +32767
integer4 bytestypical choice for integer-2147483648 to +2147483647
bigint8 byteslarge-range integer-9223372036854775808 to +9223372036854775807
numeric8 bytesexact, fixed-length representation of numbers with decimal pointup to 18 digits
double precision8 bytesvariable-precision, inexact15 decimal digits precision

1.1.1. Integer Types

The types smallint, integer, and bigint store whole numbers, that is, numbers without fractional components, of various ranges. Attempts to store values outside of the allowed range will result in an error.

1.1.2. Fixed-point Numbers

The type numeric can store fixed-point numbers with up to 18 digits without loss of precision. It is especially recommended for storing monetary amounts and other quantities where exactness is required. Calculations with numeric values yield exact results where possible, e.g. addition, subtraction, multiplication.

We use the following terms below: The precision of a numeric is the total count of significant digits in the whole number, that is, the number of digits to both sides of the decimal point. The scale of a numeric is the count of decimal digits in the fractional part, to the right of the decimal point. So the number 23.5141 has a precision of 6 and a scale of 4. Integers can be considered to have a scale of zero.

Both the maximum precision and the maximum scale of a numeric column can be configured. To declare a column of type numeric use the syntax:

NUMERIC(precision, scale)

The precision must be positive, the scale zero or positive. Alternatively:

NUMERIC(precision)

selects a scale of 0. Specifying:

NUMERIC

selects the maximum precision of 18 and a scale of 0.

Note

In the SQL standard, as well as in PostgreSQL and many other database systems, the types decimal and numeric are equivalent and both support variable-length precision. This is unlike Hyper, where numeric has fixed-length precision and decimal is not officially supported.

Note

Hyper does not support arbitrary-precision decimal numbers.

Note

If you create an extract of a relational database in Tableau, the extract will always use the Hyper double precision type, so you only get 15 digits of precision. However, you can create the extract file using the Hyper API and specify the numeric type to get up to 18 digits.

1.1.3. Floating-Point Type

The data type double precision is an inexact, variable-precision numeric type. On all currently supported platforms, these types are implementations of IEEE Standard 754 for Binary Floating-Point Arithmetic.

Inexact means that some values cannot be converted exactly to the internal format and are stored as approximations, so that storing and retrieving a value might show slight discrepancies. This is not a limitation of Hyper but an inherent trade-off of using floating-point values. In particular, the following recommendations should be taken into account when using floating-point types:

  • If you require exact storage and calculations (such as for monetary amounts), use the numeric type instead.

  • Aggregations such as sum() on floating-point values may yield inconsistent results when executed repeatedly due to parallel computation of aggregates. If you require consistent results, consider using numeric instead.

  • Comparing two floating-point values for equality might not always work as expected. Using difference to a small epsilon value is recommended instead.

On all currently supported platforms, the double precision type has a range of around 1E-307 to 1E+308 with a precision of at least 15 digits. Values that are too large or too small will cause an error. Rounding might take place if the precision of an input number is too high. Numbers too close to zero that are not representable as distinct from zero will cause an underflow error.

By default, floating point values are output in text form in their shortest precise decimal representation; the decimal value produced is closer to the true stored binary value than to any other value representable in the same binary precision. This value will use at most 17 significant decimal digits.

In addition to ordinary numeric values, the floating-point types have several special values:


Infinity
-Infinity
NaN

These represent the IEEE 754 special values infinity, negative infinity, and not-a-number, respectively. When writing these values as constants in an SQL command, you must put quotes around them, for example UPDATE table SET x = '-Infinity'. On input, these strings are recognized in a case-insensitive manner.

Note

IEEE754 specifies that NaN should not compare equal to any other floating-point value (including NaN itself).

Hyper also supports the SQL-standard notations float and float(p) for specifying inexact numeric types. Here, p specifies the minimum acceptable precision in binary digits. However, the p argument is currently ignored and all float(p) types are simply mapped to double precision. float with no precision specified is also mapped to double precision.