array_schema.md

Array Schema File

The array schema file consists of a single generic tile, with the following data:

Field	Type	Description
Array version	uint32_t	Format version number of the array schema
Allows dups	bool	New in version 5 Whether or not the array allows duplicate cells
Array type	uint8_t	Dense or sparse
Tile order	uint8_t	Row or column major
Cell order	uint8_t	Row or column major
Capacity	uint64_t	For sparse fragments, the data tile capacity
Coords filters	Filter Pipeline	The filter pipeline used as default for coordinate tiles
Offsets filters	Filter Pipeline	The filter pipeline used for cell var-len offset tiles
Validity filters	Filter Pipeline	New in version 7 The filter pipeline used for cell validity tiles
Domain	Domain	The array domain
Num attributes	uint32_t	Number of attributes in the array
Attribute 1	Attribute	First attribute
…	…	…
Attribute N	Attribute	Nth attribute
Num labels	uint32_t	New in version 18 Number of dimension labels in the array
Label 1	Dimension Label	New in version 18 First dimension label
…	…	…
Label N	Dimension Label	New in version 18 Nth dimension label
Num enumerations	uint32_t	New in version 20 Number of enumerations in the array
Enumeration name length 1	uint32_t	New in version 20 The number of characters in the enumeration 1 name
Enumeration name 1	uint8_t[]	New in version 20 The name of enumeration 1
Enumeration filename length 1	uint32_t	New in version 20 The number of characters in the enumeration 1 file
Enumeration filename 1	uint8_t[]	New in version 20 The name of the file in the __enumerations subdirectory that contains enumeration 1's data
Enumeration name length N	uint32_t	New in version 20 The number of characters in the enumeration N name
Enumeration name N	uint8_t[]	New in version 20 The name of enumeration N
Enumeration filename length N	uint32_t	New in version 20 The number of characters in the enumeration N file
Enumeration filename N	uint8_t[]	New in version 20 The name of the file in the __enumerations subdirectory that contains enumeration N's data
Current domain	Current Domain	New in version 22 The array's current domain

Domain

The domain has internal format:

Field	Type	Description
Domain datatype	uint8_t	Removed in version 5 Datatype of all dimensions
Num dimensions	uint32_t	Dimensionality/rank of the domain
Dimension 1	Dimension	First dimension
…	…	…
Dimension N	Dimension	Nth dimension

Dimension

The dimension has internal format:

Field	Type	Description
Dimension name length	uint32_t	Number of characters in dimension name
Dimension name	uint8_t[]	Dimension name character array
Dimension datatype	uint8_t	New in version 5 Datatype of the coordinate values
Cell val num	uint32_t	New in version 5 Number of coordinate values per cell. For variable-length dimensions, this is std::numeric_limits<uint32_t>::max()
Filters	Filter Pipeline	New in version 5 The filter pipeline used on coordinate value tiles
Domain size	uint64_t	New in version 5 The domain size in bytes
Domain	uint8_t[]	Byte array of length equal to domain size above, storing the min, max values of the dimension.
Null tile extent	uint8_t	1 if the dimension has a null tile extent, else 0.
Tile extent	uint8_t[]	Byte array of length equal to the dimension datatype size, storing the space tile extent of this dimension.

Attribute

The attribute has internal format:

Field	Type	Description
Attribute name length	uint32_t	Number of characters in attribute name
Attribute name	uint8_t[]	Attribute name character array
Attribute datatype	uint8_t	Datatype of the attribute values
Cell val num	uint32_t	Number of attribute values per cell. For variable-length attributes, this is std::numeric_limits<uint32_t>::max()
Filters	Filter Pipeline	The filter pipeline used on attribute value tiles
Fill value size	uint64_t	New in version 6 The size in bytes of the fill value
Fill value	uint8_t[]	New in version 6 The fill value
Nullable	bool	New in version 7 Whether or not the attribute can be null
Fill value validity	uint8_t	New in version 7 The validity fill value
Order	uint8_t	New in version 17 Order of the data stored in the attribute. This may be unordered, increasing or decreasing

Dimension Label

The dimension label has internal format:

Field	Type	Description
Dimension index	uint32_t	Index of the dimension the label is for
Label order	uint8_t	Order of the label data
Dimension label name length	uint64_t	Number of characters in the dimension label name
Dimension label name	uint8_t []	The name of the dimension label
Relative URI	uint8_t	If the URI of the array the label data is stored in is relative to this array
URI length	uint64_t	The number of characters in the URI
URI	uint8_t []	The URI the label data is stored in
Label attribute name length	uint32_t	The length of the attribute name of the label data
Label attribute name	uint8_t []	The name of the attribute the label data is stored in
Label datatype	uint8_t	The datatype of the label data
Label cell_val_num	uint32_t	The number of values per cell of the label data. For variable-length labels, this is std::numeric_limits<uint32_t>::max()
Label domain size	uint64_t	The size of the label domain
Label domain start size	uint64_t	The size of the first value of the domain for variable-length datatypes. For fixed-length labels, this is 0
Label domain data	uint8_t[]	Byte array of length equal to domain size above, storing the min, max values of the dimension
Is external	uint8_t	If the URI is not stored as part of this array

Current Domain

If a current domain is empty, only the version number and the empty flag are serialized to storage.

The current domain format is versioned separately from arrays. The current version is 1.

Field	Type	Description
Version number	uint32_t	Current domain version number
Empty	uint8_t	Whether the current domain has a representation (e.g. NDRectangle) set
Type	uint8_t	The type of current domain stored in this file
NDRectangle	MBR	A hyperrectangle defined using 1DRange items for each dimension