This document is to clarify the differences between the ideas of "deleting" a resource from Fedora and "purging" a resource from Fedora.

Delete

When you delete a resource from Fedora it is replaced by a "tombstone" that is returned when you try to access the resource.

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At the OCFL layer a tombstone is indicated as a change in the hidden Fedora files. These sidecar files Fedora uses to track various Fedora Header File for the deleted resource. Fedora uses these sidecar files to track information the application needs for each resource. Nothing is removed when the object is "deleted" instead the sidecar file fcr-root.json file is updated to change the value of the "deleted" key from "false" to "true" (as well as the "lastModifiedDate" value)

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.
└── ocfl-root/5ce/631/395/5ce63139564a3a617705f0169f200433debd2dd4b63b3fb583a5fe9f7de76539/
    ├── 0=ocfl_object_1.1
    ├── inventory.json
    ├── inventory.json.sha512
    ├── v1/
    │   ├── inventory.json
    │   ├── inventory.json.sha512
    │   └── content/
    │       ├── fcr-container.nt
    │       └── .fcrepo/
    │           └── fcr-root.json
    └── v2/
        ├── inventory.json
        ├── inventory.json.sha512
        └── content/
            └── .fcrepo/
                └── fcr-root.json

Purge

It is understandable that in some situations you might want to complete completely remove a resource and rebuild it. In this situation you need to "purge" the object from your repository. To do this you make a "delete" request to the tombstone itself.

You can find the tombstone's URI by checking the headers returned on the deleted resource.

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In contrast to a delete, a purge completely removes the resource from your OCFL file-system. It also removes any empty parent sub-directories up to the OCFL root directory (called "ocfl-root" by default).

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For example looking at the OCFL root directory of a

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repository with only the deleted resource "test-resource" before the purge

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:

.
└── ocfl-root/
    ├── 0004-hashed-n-tuple-storage-layout.md
    ├── 0=ocfl_1.1
    ├── 141 <- the repository root resource
    ├── 5ce <- the deleted resource "test-resource"
    ├── extensions
    ├── ocfl_1.1.md
    ├── ocfl_extensions_1.0.md
    └── ocfl_layout.json

After purging the resource "test-resource", the OCFL root looks like this

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:

.
└── ocfl-root/
    ├── 0004-hashed-n-tuple-storage-layout.md
    ├── 0=ocfl_1.1
    ├── 141 <- the repository root resource
    ├── extensions
    ├── ocfl_1.1.md
    ├── ocfl_extensions_1.0.md
    └── ocfl_layout.json

Because no other

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resources in the repository

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were stored within the "5ce" directory in this example, the entire directory structure was removed. See Fedora OCFL Object Structure#StorageHierarchyLayout for details of how these subdirectories are named.