Numeric types - Amazon Redshift
Integer typesDECIMAL or NUMERIC typeNotes about using 128-bit DECIMAL or NUMERIC columnsFloating-Point types

Numeric types

Topics

Numeric data types include integers, decimals, and floating-point numbers.

Integer types

Use the SMALLINT, INTEGER, and BIGINT data types to store whole numbers of various ranges. You cannot store values outside of the allowed range for each type.

Name Storage Range
SMALLINT or INT2 2 bytes -32768 to +32767
INTEGER, INT, or INT4 4 bytes -2147483648 to +2147483647
BIGINT or INT8 8 bytes -9223372036854775808 to 9223372036854775807

DECIMAL or NUMERIC type

Use the DECIMAL or NUMERIC data type to store values with a user-defined precision. The DECIMAL and NUMERIC keywords are interchangeable. In this document, decimal is the preferred term for this data type. The term numeric is used generically to refer to integer, decimal, and floating-point data types.

Storage Range
Variable, up to 128 bits for uncompressed DECIMAL types. 128-bit signed integers with up to 38 digits of precision.

Define a DECIMAL column in a table by specifying a precision and scale: 

decimal(precision, scale)
precision

The total number of significant digits in the whole value: the number of digits on both sides of the decimal point. For example, the number 48.2891 has a precision of 6 and a scale of 4. The default precision, if not specified, is 18. The maximum precision is 38.

If the number of digits to the left of the decimal point in an input value exceeds the precision of the column minus its scale, the value cannot be copied into the column (or inserted or updated). This rule applies to any value that falls outside the range of the column definition. For example, the allowed range of values for a numeric(5,2) column is -999.99 to 999.99.

scale

The number of decimal digits in the fractional part of the value, to the right of the decimal point. Integers have a scale of zero. In a column specification, the scale value must be less than or equal to the precision value. The default scale, if not specified, is 0. The maximum scale is 37.

If the scale of an input value that is loaded into a table is greater than the scale of the column, the value is rounded to the specified scale. For example, the PRICEPAID column in the SALES table is a DECIMAL(8,2) column. If a DECIMAL(8,4) value is inserted into the PRICEPAID column, the value is rounded to a scale of 2. 

insert into sales
values (0, 8, 1, 1, 2000, 14, 5, 4323.8951, 11.00, null);

select pricepaid, salesid from sales where salesid=0;

pricepaid | salesid
-----------+---------
4323.90 |       0
(1 row)

However, results of explicit casts of values selected from tables are not rounded.

Note

The maximum positive value that you can insert into a DECIMAL(19,0) column is 9223372036854775807 (263 -1). The maximum negative value is -9223372036854775808. For example, an attempt to insert the value 9999999999999999999 (19 nines) will cause an overflow error. Regardless of the placement of the decimal point, the largest string that Amazon Redshift can represent as a DECIMAL number is 9223372036854775807. For example, the largest value that you can load into a DECIMAL(19,18) column is 9.223372036854775807.

These rules are because DECIMAL values with 19 or fewer significant digits of precision are stored internally as 8-byte integers, while DECIMAL values with 20 to 38 significant digits of precision are stored as 16-byte integers.

Notes about using 128-bit DECIMAL or NUMERIC columns

Do not arbitrarily assign maximum precision to DECIMAL columns unless you are certain that your application requires that precision. 128-bit values use twice as much disk space as 64-bit values and can slow down query execution time.

Floating-Point types

Use the REAL and DOUBLE PRECISION data types to store numeric values with variable precision. These types are inexact types, meaning that some values are stored as approximations, such that storing and returning a specific value may result in slight discrepancies. If you require exact storage and calculations (such as for monetary amounts), use the DECIMAL data type.

REAL represents the single-precision floating point format, according to the IEEE Standard 754 for Binary Floating-Point Arithmetic. It has a precision of about 6 digits, and a range of around 1E-37 to 1E+37. You can also specify this data type as FLOAT4.

DOUBLE PRECISION represents the double-precision floating point format, according to the IEEE Standard 754 for Binary Floating-Point Arithmetic. It has a precision of about 15 digits, and a range of around 1E-307 to 1E+308. You can also specify this data type as FLOAT or FLOAT8.

In addition to ordinary numeric values, the floating-point types have several special values. Use single quotation marks around these values when using them in SQL:

  • NaN – not-a-number

  • Infinity – infinity

  • -Infinity – negative infinity

For example, to insert not-a-number in column day_charge of table customer_activity run the following SQL:

insert into customer_activity(day_charge) values('NaN');