org.apache.hadoop.fs

Interface Options.CreateFileOptionKeys

Enclosing class:

Options

@InterfaceAudience.Public
 @InterfaceStability.Evolving
public static interface Options.CreateFileOptionKeys

The standard createFile() options.

If an option is not supported during file creation and it is considered part of a commit protocol, then, when supplied in a must() option, it MUST be rejected.

Field Summary

Fields

Modifier and Type	Field and Description
static String	FS_OPTION_CREATE_CONDITIONAL_OVERWRITE createFile() option to write a file in the close() operation iff there is nothing at the destination.
static String	FS_OPTION_CREATE_CONDITIONAL_OVERWRITE_ETAG Overwrite a file only if there is an Etag match.
static String	FS_OPTION_CREATE_CONTENT_TYPE String to define the content filetype.
static String	FS_OPTION_CREATE_IN_CLOSE A flag which requires the filesystem to create files/objects in close(), rather than create/createFile.

Field Detail

FS_OPTION_CREATE_CONDITIONAL_OVERWRITE

static final String FS_OPTION_CREATE_CONDITIONAL_OVERWRITE

createFile() option to write a file in the close() operation iff there is nothing at the destination. this is the equivalent of create(path, overwrite=true) except that the existence check is postponed to the end of the write.

Value "fs.option.create.conditional.overwrite".

This can be set in the builder.

1. It is for object stores stores which only upload/manifest files at the end of the stream write.
2. Streams which support it SHALL not manifest any object to the destination path until close()
3. It MUST be declared as a stream capability in streams for which this overwrite is enabled.
4. It MUST be exported as a path capability for all stores where the feature is available and enabled
5. If passed to a filesystem as a must() parameter where the option value is true, and it is supported/enabled, the FS SHALL omit all overwrite checks in create, including for the existence of an object or a directory underneath. Instead, during close() the object will only be manifest at the target path if there is no object at the destination.
6. The existence check and object creation SHALL be atomic.
7. If passed to a filesystem as a must() parameter where the option value is true, and the FS does not recognise the feature, or it is recognized but disabled on this FS instance, the filesystem SHALL reject the request.
8. If passed to a filesystem as a opt() parameter where the option value is true, the filesystem MAY ignore the request, or it MAY enable the feature. Any filesystem which does not support the feature, including from older releases, SHALL ignore it.

See Also:

Constant Field Values

FS_OPTION_CREATE_CONDITIONAL_OVERWRITE_ETAG

static final String FS_OPTION_CREATE_CONDITIONAL_OVERWRITE_ETAG

Overwrite a file only if there is an Etag match. This option takes a string, Value "fs.option.create.conditional.overwrite.etag".

This is similar to FS_OPTION_CREATE_CONDITIONAL_OVERWRITE.

1. If supported and enabled, it SHALL be declared as a capability of the filesystem
2. If supported and enabled, it SHALL be declared as a capability of the stream
3. The string passed as the value SHALL be the etag value as returned by EtagSource.getEtag()
4. This value MUST NOT be empty
5. If passed to a filesystem which supports it, then when the file is created, the store SHALL check for the existence of a file/object at the destination path.
6. If there is no object there, the operation SHALL be rejected by raising either a org.apache.hadoop.fs.FileAlreadyExistsException exception, or ajava.nio.file.FileAlreadyExistsException
7. If there is an object there, its Etag SHALL be compared to the value passed here.
8. If there is no match, the operation SHALL be rejected by raising either a org.apache.hadoop.fs.FileAlreadyExistsException exception, or ajava.nio.file.FileAlreadyExistsException
9. If the etag does match, the file SHALL be created.
10. The check and create SHALL be atomic
11. The check and create MAY be at the end of the write, in close(), or it MAY be in the create() operation. That is: some stores MAY perform the check early
12. If supported and enabled, stores MAY check for the existence of subdirectories; this behavior is implementation-specific.

See Also:

Constant Field Values

FS_OPTION_CREATE_IN_CLOSE

static final String FS_OPTION_CREATE_IN_CLOSE

A flag which requires the filesystem to create files/objects in close(), rather than create/createFile.

Object stores with this behavior should also export it as a path capability. Value "fs.option.create.in.close".

See Also:

Constant Field Values

FS_OPTION_CREATE_CONTENT_TYPE

static final String FS_OPTION_CREATE_CONTENT_TYPE

String to define the content filetype. Value "fs.option.create.content.type".

See Also:

Constant Field Values