System-defined properties

ApertureDB defines a set of properties (called “system-defined properties”) for different objects. Some properties are present in all objects (like “_uniqueid”), while others are only present in specific objects (like “_label” for BoundingBox, Polygons, or Descriptors). All system-defined properties start with “_” prefix.

Here we detail the set of properties for each Object:

Object	Properties	Type	Notes
All Objects	_uniqueid	string	Unique id for the object
	_create_txn	number	Transaction id that created the object
DescriptorSet	_name	string	Name of the set
	_dimensions	number	Dimensionality of the Descriptors
	_engines	string	List of engines available for KNN
	_metrics	string	List of metrics available for KNN
	_count	number	Number of Descriptors in the Set
	_segment_size	number	Number of Descriptors on each segment
	_max_segments	number	Maximum number of segments
	_splits	number	Number of splits
Descriptor	_label	string	Label describing the content of the Descriptor
	_set_name	string	Name of the set the Descriptor belongs to
BoundingBox	_label	string	Label describing the content of BoundingBox
	_coordinates	rect	rectangle
	_area	number	Area (in pixels) of the BoundingBox
Polygon	_label	string	Label describing the content of Polygon
	_polygons	poly	polygons
	_area	number	Area (in pixels) of the Polygon
	_bounds	number	The smallest rectangle containing the Polygon
Video	_fps	number	Average frames per second
	_frame_count	number	Number of frames in the video
	_frame_width	number	Width of the frame
	_frame_height	number	Height of the frame
Frame	_label	string	Label describing the content of Polygon
	_frame_number	number	frame_number
	_time_offset	string	time_offset
	_time_fraction	number	time_fraction

NOTE: Only properties in bold are modifiable by the user.

NOTE: Only the “==” and “in” operators are supported for “_uniqueid”.