diff --git a/swh/storage/algos/identifier.py b/swh/storage/algos/identifier.py
new file mode 100644
--- /dev/null
+++ b/swh/storage/algos/identifier.py
@@ -0,0 +1,43 @@
+# Copyright (C) 2022  The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+from typing import Iterable, List
+
+from swh.model.model import ObjectType, Sha1Git
+from swh.storage.interface import StorageInterface
+
+
+def identifiers_missing(
+    storage: StorageInterface, obj_type: ObjectType, obj_ids: List[Sha1Git]
+) -> Iterable[Sha1Git]:
+    """Lookup missing Software Heritage hashes, choosing the correct
+    underlying method based on the type.
+
+    The idea is that conceptually we are looking up a list of Core
+    SWHIDs with the same object type part, and to enforce that we pash
+    the type and the hashes separately.
+
+    Args:
+        storage (swh.storage.interface.StorageInterface): the storage
+        instance
+
+        obj_type: What type of object are the hashes supposed to point
+        to.
+
+        obj_ids: list of hashes to look up
+
+    Yields:
+        missing hashes for the given object type
+    """
+
+    fun = {
+        ObjectType.CONTENT: storage.content_missing_per_sha1_git,
+        ObjectType.DIRECTORY: storage.directory_missing,
+        ObjectType.REVISION: storage.revision_missing,
+        ObjectType.RELEASE: storage.release_missing,
+        ObjectType.SNAPSHOT: storage.snapshot_missing,
+    }[obj_type]
+
+    return fun(obj_ids)
diff --git a/swh/storage/tests/algos/test_identifer.py b/swh/storage/tests/algos/test_identifer.py
new file mode 100644
--- /dev/null
+++ b/swh/storage/tests/algos/test_identifer.py
@@ -0,0 +1,56 @@
+# Copyright (C) 2022  The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+import pytest
+import random
+
+from swh.model.model import ObjectType, Sha1Git
+from swh.storage.algos.identifier import identifiers_missing
+from ..storage_data import StorageData
+
+
+@pytest.fixture(scope="function")
+def missing_id() -> Sha1Git:
+    return bytes(random.randint(0, 255) for _ in range(20))
+
+
+@pytest.mark.parametrize("content_id", [c.sha1_git for c in StorageData.contents])
+def test_missing_contents(swh_storage, content_id, missing_id):
+    hashes = [content_id, missing_id]
+
+    result = identifiers_missing(swh_storage, ObjectType.CONTENT, hashes)
+    assert result == {missing_id}
+
+
+@pytest.mark.parametrize("directory_id", [o.id for o in StorageData.directories])
+def test_missing_directories(swh_storage, directory_id, missing_id):
+    hashes = [directory_id, missing_id]
+
+    result = identifiers_missing(swh_storage, ObjectType.Directories, hashes)
+    assert result == {missing_id}
+
+
+@pytest.mark.parametrize("revision_id", [o.id for o in StorageData.revisions])
+def test_missing_revisions(swh_storage, revision_id, missing_id):
+    hashes = [revision_id, missing_id]
+
+    result = identifiers_missing(swh_storage, ObjectType.REVISION, hashes)
+    assert result == {missing_id}
+
+
+@pytest.mark.parametrize("release_id", [o.id for o in StorageData.releases])
+def test_missing_releases(swh_storage, release_id, missing_id):
+    hashes = [release_id, missing_id]
+
+    result = identifiers_missing(swh_storage, ObjectType.RELEASE, hashes)
+    assert result == {missing_id}
+
+
+@pytest.mark.parametrize("snapshot_id", [o.id for o in StorageData.snapshots])
+def test_missing_snapshots(swh_storage, snapshot_id, missing_id):
+    hashes = [snapshot_id, missing_id]
+
+    result = identifiers_missing(swh_storage, ObjectType.CONTENT, hashes)
+    assert result == {missing_id}