UCObjectStore

class composer.utils.UCObjectStore(path)

Utility class for uploading and downloading data from Databricks Unity Catalog (UC) Volumes.

Note

Using this object store requires setting DATABRICKS_HOST and DATABRICKS_TOKEN environment variables with the right credentials to be able to access the files in the unity catalog volumes.

Parameters

path (str) – The Databricks UC Volume path that is of the format Volumes/<catalog-name>/<schema-name>/<volume-name>/path/to/folder. Note that this prefix should always start with /Volumes and adhere to the above format since this object store only suports Unity Catalog Volumes and not other Databricks Filesystems.

download_object(object_name, filename, overwrite=False, callback=None)

Download the given object from UC Volumes to the specified filename.

Parameters

• object_name (str) – The name of the object to download i.e. path relative to the root of the volume.

• filename (str | Path) – The local path where a the file needs to be downloaded.

• overwrite (bool, optional) – Whether to overwrite an existing file at filename, if it exists. (default: False)

• callback ((int) -> None, optional) – Unused

Raises

• FileNotFoundError – If the file was not found in UC volumes.

• ObjectStoreTransientError – If there was any other error querying the Databricks UC volumes that should be retried.

get_object_size(object_name)

Get the size of the object in UC volumes in bytes.

Parameters

object_name (str) – The name of the object.

Returns

int – The object size, in bytes.

Raises

• FileNotFoundError – If the file was not found in the object store.

• IsADirectoryError – If the object is a directory, not a file.

get_uri(object_name)

Returns the URI for object_name.

Note

This function does not check that object_name is in the object store. It computes the URI statically.

Parameters

object_name (str) – The object name.

Returns

str – The URI for object_name in the object store.

list_objects(prefix)

List all objects in the object store with the given prefix.

Parameters

prefix (str) – The prefix to search for.

Returns

list[str] – A list of object names that match the prefix.

upload_object(object_name, filename, callback=None)

Upload a file from local to UC volumes.

Parameters

• object_name (str) – Name of the stored object in UC volumes w.r.t. volume root.

• filename (str | Path) – Path the the object on disk

• callback ((int, int) -> None, optional) – Unused

static validate_path(path)

Parses the given path to extract the UC Volume prefix from the path.

Note

This function only uses the first 4 directories from the path to construct the UC Volumes prefix and will ignore the rest of the directories in the path

Parameters

• path (str) – The Databricks UC Volume path of the format

• Volumes/<catalog-name>/<schema-name>/<volume-name>/path/to/folder. –