Skip to content

Latest commit

 

History

History
99 lines (77 loc) · 4.1 KB

array_schema.md

File metadata and controls

99 lines (77 loc) · 4.1 KB
Raw
title
Array Schema

Current Array Schema Version

The current array schema version(>=10) is a folder called __schema located here:

my_array                            # array folder
   |  ...
   |_ __schema                      # array schema folder
         |_ <timestamped_name>      # array schema file
         |_ ...

<timestamped_name> has format __timestamp_timestamp_uuid, where:

  • timestamp is timestamp in milliseconds elapsed since 1970-01-01 00:00:00 +0000 (UTC)
  • uuid is a unique identifier

The array schema folder can contain:

Previous Array Schema Version

The previous array schema version(<=9) has a file named __array_schema.tdb and is located here:

my_array                   # array folder
   |_ ....
   |_ __array_schema.tdb   # array schema file
   |_ ...

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 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 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

Domain

The domain has internal format:

Field Type Description
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 char[] Dimension name character array
Dimension datatype uint8_t Datatype of the coordinate values
Cell val num uint32_t Number of coordinate values per cell. For variable-length dimensions, this is std::numeric_limits<uint32_t>::max()
Filters Filter Pipeline The filter pipeline used on coordinate value tiles
Domain size uint64_t[] 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 char[] 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 The size in bytes of the fill value
Fill value uint8_t[] The fill value
Nullable bool Whether or not the attribute can be null
Fill value validity uint8_t The validity fill value