Data Types

Data types

Each product property can be of one of the following supported types: boolean, integer, long, real, text, timestamp, uuid, geometry, and json. These types are described in detail below.

The boolean type represents a truth value and has two possible states: true and false.

The valid literal boolean values are:

true

false

The integer types (integer and long) represent whole numbers. The integer type is a 32-bit signed integer and can be used to represent values in the range -2147483648 to +2147483647 (inclusive). The long type is a 64-bit signed integer and can be used to represent values in the range -9223372036854775808 to +9223372036854775807 (inclusive).

Some examples of literal integer values:

-3

0

10

+99

The floating point type (real) represents fractional numbers. The real type is a double precision floating point number and has a typical range of around 1E-307 to 1E+308 with a precision of at least 15 digits.

Some examples of literal real values:

1E-5

1.E+10

-3.1415E0

1.0

The text type represents text. Literal values are enclosed in double quotes and most common backslash escape sequences are recognized. To include a double quote or a backslash inside a text literal, they must be escaped with a backslash, i.e. \" and \\.

Some examples of literal text values:

"Hello world!\n"

"This is a so-called \"text\" literal."

The timestamp type represents an instance in time with microsecond resolution. Time zone information is not included. Although throughout muninn all timestamps are expressed in UTC, users (and especially product type plug-in developers) can choose a different convention (e.g. local time) for custom product properties.

The minimum and maximum timestamp values are 0001-01-01T00:00:00.000000 and 9999-12-31T23:59:59.999999 respectively, which may also be written as 0000-00-00T00:00:00.000000 and 9999-99-99T99:99:99.999999 for convenience.

Some examples of literal timestamp values:

2000-01-01

2000-01-01T00:00:00

2000-01-01T00:00:00.

2000-01-01T00:00:00.3

1999-12-21T23:59:59.999999

0000-00-00

0000-00-00T00:00:00

9999-99-99T99:99:99.99

The uuid type represents a universally unique identifier, a 128-bit number that is used to uniquely identify products in a muninn archive.

Some examples of literal uuid values:

32a61528-a712-427a-b28f-8ebd5b472b16

873dd103-2115-4bf8-9f05-d0eb4b3f71ea

bdc10916-d89f-416c-8987-a9c2af9b1ef7

The geometry type represents two-dimensional geometric objects. The spatial reference system used is WGS84 (SRID=4326). Longitude is measured in degrees East, latitude is measured in degrees North. The coordinates of a point are ordered as (longitude, latitude).

The geometric objects currently supported are: Point, LineString, Polygon, MultiPoint, MultiLineString, and MultiPolygon.

The linear ring(s) that make up a polygon should be topologically closed. In other words, the start and end point of any linear ring should be equal. A polygon of which the exterior ring is ordered anti-clockwise is seen from the “top”. Any interior rings should be ordered in the direction opposite to the exterior ring.

A sub-set of the Well Known Text (WKT) markup language is used to represent literal geometry values. This sub-set is limited to the supported geometric objects listed above. Only two-dimensional coordinates are supported. Empty geometries are supported. An empty geometry is represented by the name of the geometry type followed by the keyword EMPTY.

Some examples of literal geometry values:

POINT (3.0 55.0)

LINESTRING (3.0 55.0, 3.0 80.0, 5.0 75.0)

POLYGON ((5.0 52.0, 6.0 53.0, 3.0 52.5, 5.0 52.0))

POLYGON EMPTY

The json type represents JSON objects.