array_file_hierarchy.md

title	Array File Hierarchy

An array is a folder with the following structure:

my_array                                # array folder
    |_ __schema                         # array schema folder
          |_ <timestamp_name>           # array schema files
          |_ ...
          |_ __enumerations             # array enumerations folder
    |_ __fragments                      # array fragments folder
          |_ <timestamped_name>         # fragment folder
          |_ ...
    |_ __commits                        # array commits folder
          |_ <timestamped_name>.wrt     # fragment write file
          |_ ...
          |_ <timestamped_name>.del     # delete commit file
          |_ ...
          |_ <timestamped_name>.upd     # update commit file
          |_ ...
          |_ <timestamped_name>.vac     # fragment vacuum file
          |_ ...
          |_ <timestamped_name>.con     # consolidated commits file
          |_ ...
          |_ <timestamped_name>.ign     # ignore file for consolidated commits file
    |_ __fragment_meta                  # consolidated fragment metadata folder
          |_ <timestamped_name>.meta    # consolidated fragment meta file
          |_ ...
    |_ __meta                           # array metadata folder
    |_ __labels                         # dimension label folder
    |_ <timestamped_name>               # legacy fragment folder
          |_ ...
    |_ <timestamped_name>.ok            # legacy fragment write file
    |_ <timestamped_name>.meta          # legacy consolidated fragment meta file
    |_ __array_schema.tdb               # legacy array schema file

Inside the array folder, you can find the following:

• Inside of a __schema folder, any number of array schema files <timestamped_name>.
  • Note: the name does not include the format version.
  • New in version 20 Inside of the schema folder, an enumerations folder __enumerations.
• Inside of a __meta folder, any number of array metadata files <timestamped_name>.
• Inside of a __fragments folder, any number of fragment folders <timestamped_name>.
• New in version 18 Inside of a __labels folder, additional TileDB arrays storing dimension label data.
• New in version 12 Inside of a __commits folder:
  • Any number of empty files <timestamped_name>.wrt, each associated with fragment folder <timestamped_name>, indicating that the fragment has been committed (i.e., its write process finished successfully). If the WRT file does not exist, the corresponding fragment must be ignored when reading the array.
  • Any number of consolidated commits files of the form <timestamped_name>.con.
  • Any number of ignore files of the form <timestamped_name>.ign.
  • New in version 16 Any number of delete commit files of the form <timestamped_name>.del.
  • New in version 16 Any number of update commit files of the form <timestamped_name>.upd.
• New in version 12 Inside of a __fragment_meta folder, any number of consolidated fragment metadata files of the form <timestamped_name>.meta.

Note

Prior to version 12, fragments, commit files, and consolidated fragment metadata were stored directly in the array folder and the extension of commit files was .ok instead of .wrt. Implementations must support arrays that contain data in both the old and the new hierarchy at the same time.

Note

Prior to version 10, the array schema was stored in a single __array_schema.tdb file in the array folder. Implementations must support arrays that contain both __array_schema.tdb and schemas in the __schema folder at the same time. For the purpose of array schema evolution, the timestamp of __array_schema.tdb must be considered to be earlier than any schema in the __schema folder.

Note

Prior to version 5, commit files were not written. Fragments of these versions are considered to be committed if their corresponding fragment metadata file exists.