From 5c67734f6cfc03ae90edc3ee0713bc1be427e6cc Mon Sep 17 00:00:00 2001
From: Stephan Hoyer <shoyer@google.com>
Date: Thu, 28 Aug 2025 10:55:57 -0700
Subject: [PATCH 1/3] Remove Store.set_partial_writes

This feature was unused by the rest of Zarr-Python, and was only
implemented for LocalStore and stores that wrap other stores.

The Zarr v3 spec still mentions partial writes, so it should probably
also be updated.
---
 changes/2859.removal.rst         |  2 ++
 src/zarr/abc/store.py            | 25 ++++++------------------
 src/zarr/storage/_common.py      | 11 +----------
 src/zarr/storage/_fsspec.py      |  6 ------
 src/zarr/storage/_local.py       | 33 ++++----------------------------
 src/zarr/storage/_logging.py     | 13 -------------
 src/zarr/storage/_memory.py      |  8 --------
 src/zarr/storage/_obstore.py     | 11 -----------
 src/zarr/storage/_wrapper.py     |  9 ---------
 src/zarr/storage/_zip.py         |  7 -------
 src/zarr/testing/stateful.py     |  7 -------
 src/zarr/testing/store.py        |  4 ++--
 tests/test_store/test_fsspec.py  |  3 ---
 tests/test_store/test_local.py   |  3 ---
 tests/test_store/test_logging.py |  3 ---
 tests/test_store/test_memory.py  |  6 ------
 tests/test_store/test_object.py  |  5 -----
 tests/test_store/test_wrapper.py |  3 ---
 tests/test_store/test_zip.py     |  3 ---
 19 files changed, 15 insertions(+), 147 deletions(-)
 create mode 100644 changes/2859.removal.rst

diff --git a/changes/2859.removal.rst b/changes/2859.removal.rst
new file mode 100644
index 0000000000..bd417855f3
--- /dev/null
+++ b/changes/2859.removal.rst
@@ -0,0 +1,2 @@
+The ``Store.set_partial_writes`` method, which was not used by Zarr-Python, has been removed.
+``store.supports_partial_writes`` is now always ``False``.
diff --git a/src/zarr/abc/store.py b/src/zarr/abc/store.py
index 53e981c3bd..c94ecfdd4b 100644
--- a/src/zarr/abc/store.py
+++ b/src/zarr/abc/store.py
@@ -4,7 +4,7 @@
 from asyncio import gather
 from dataclasses import dataclass
 from itertools import starmap
-from typing import TYPE_CHECKING, Protocol, runtime_checkable
+from typing import TYPE_CHECKING, Literal, Protocol, runtime_checkable
 
 if TYPE_CHECKING:
     from collections.abc import AsyncGenerator, AsyncIterator, Iterable
@@ -310,25 +310,12 @@ async def delete(self, key: str) -> None:
         ...
 
     @property
-    @abstractmethod
-    def supports_partial_writes(self) -> bool:
-        """Does the store support partial writes?"""
-        ...
-
-    @abstractmethod
-    async def set_partial_values(
-        self, key_start_values: Iterable[tuple[str, int, BytesLike]]
-    ) -> None:
-        """Store values at a given key, starting at byte range_start.
+    def supports_partial_writes(self) -> Literal[False]:
+        """Does the store support partial writes?
 
-        Parameters
-        ----------
-        key_start_values : list[tuple[str, int, BytesLike]]
-            set of key, range_start, values triples, a key may occur multiple times with different
-            range_starts, range_starts (considering the length of the respective values) must not
-            specify overlapping ranges for the same key
+        Partial writes are no longer used by Zarr, so this is always false.
         """
-        ...
+        return False
 
     @property
     @abstractmethod
@@ -499,7 +486,7 @@ async def get(
         self, prototype: BufferPrototype, byte_range: ByteRequest | None = None
     ) -> Buffer | None: ...
 
-    async def set(self, value: Buffer, byte_range: ByteRequest | None = None) -> None: ...
+    async def set(self, value: Buffer) -> None: ...
 
     async def delete(self) -> None: ...
 
diff --git a/src/zarr/storage/_common.py b/src/zarr/storage/_common.py
index 66a53c19df..ff757f9a99 100644
--- a/src/zarr/storage/_common.py
+++ b/src/zarr/storage/_common.py
@@ -163,7 +163,7 @@ async def get(
             prototype = default_buffer_prototype()
         return await self.store.get(self.path, prototype=prototype, byte_range=byte_range)
 
-    async def set(self, value: Buffer, byte_range: ByteRequest | None = None) -> None:
+    async def set(self, value: Buffer) -> None:
         """
         Write bytes to the store.
 
@@ -171,16 +171,7 @@ async def set(self, value: Buffer, byte_range: ByteRequest | None = None) -> Non
         ----------
         value : Buffer
             The buffer to write.
-        byte_range : ByteRequest, optional
-            The range of bytes to write. If None, the entire buffer is written.
-
-        Raises
-        ------
-        NotImplementedError
-            If `byte_range` is not None, because Store.set does not support partial writes yet.
         """
-        if byte_range is not None:
-            raise NotImplementedError("Store.set does not have partial writes yet")
         await self.store.set(self.path, value)
 
     async def delete(self) -> None:
diff --git a/src/zarr/storage/_fsspec.py b/src/zarr/storage/_fsspec.py
index bbb934cc7d..cb6b4f55ed 100644
--- a/src/zarr/storage/_fsspec.py
+++ b/src/zarr/storage/_fsspec.py
@@ -418,12 +418,6 @@ async def get_partial_values(
 
         return [None if isinstance(r, Exception) else prototype.buffer.from_bytes(r) for r in res]
 
-    async def set_partial_values(
-        self, key_start_values: Iterable[tuple[str, int, BytesLike]]
-    ) -> None:
-        # docstring inherited
-        raise NotImplementedError
-
     async def list(self) -> AsyncIterator[str]:
         # docstring inherited
         allfiles = await self.fs._find(self.path, detail=False, withdirs=False)
diff --git a/src/zarr/storage/_local.py b/src/zarr/storage/_local.py
index 717ed04144..f64da71bb4 100644
--- a/src/zarr/storage/_local.py
+++ b/src/zarr/storage/_local.py
@@ -77,23 +77,12 @@ def _atomic_write(
         raise
 
 
-def _put(
-    path: Path,
-    value: Buffer,
-    start: int | None = None,
-    exclusive: bool = False,
-) -> int | None:
+def _put(path: Path, value: Buffer, exclusive: bool = False) -> int:
     path.parent.mkdir(parents=True, exist_ok=True)
     # write takes any object supporting the buffer protocol
     view = value.as_buffer_like()
-    if start is not None:
-        with path.open("r+b") as f:
-            f.seek(start)
-            f.write(view)
-        return None
-    else:
-        with _atomic_write(path, "wb", exclusive=exclusive) as f:
-            return f.write(view)
+    with _atomic_write(path, "wb", exclusive=exclusive) as f:
+        return f.write(view)
 
 
 class LocalStore(Store):
@@ -111,14 +100,12 @@ class LocalStore(Store):
     ----------
     supports_writes
     supports_deletes
-    supports_partial_writes
     supports_listing
     root
     """
 
     supports_writes: bool = True
     supports_deletes: bool = True
-    supports_partial_writes: bool = True
     supports_listing: bool = True
 
     root: Path
@@ -253,19 +240,7 @@ async def _set(self, key: str, value: Buffer, exclusive: bool = False) -> None:
                 f"LocalStore.set(): `value` must be a Buffer instance. Got an instance of {type(value)} instead."
             )
         path = self.root / key
-        await asyncio.to_thread(_put, path, value, start=None, exclusive=exclusive)
-
-    async def set_partial_values(
-        self, key_start_values: Iterable[tuple[str, int, bytes | bytearray | memoryview]]
-    ) -> None:
-        # docstring inherited
-        self._check_writable()
-        args = []
-        for key, start, value in key_start_values:
-            assert isinstance(key, str)
-            path = self.root / key
-            args.append((_put, path, value, start))
-        await concurrent_map(args, asyncio.to_thread, limit=None)  # TODO: fix limit
+        await asyncio.to_thread(_put, path, value, exclusive=exclusive)
 
     async def delete(self, key: str) -> None:
         """
diff --git a/src/zarr/storage/_logging.py b/src/zarr/storage/_logging.py
index a2164a418f..dd20d49ae5 100644
--- a/src/zarr/storage/_logging.py
+++ b/src/zarr/storage/_logging.py
@@ -115,11 +115,6 @@ def supports_deletes(self) -> bool:
         with self.log():
             return self._store.supports_deletes
 
-    @property
-    def supports_partial_writes(self) -> bool:
-        with self.log():
-            return self._store.supports_partial_writes
-
     @property
     def supports_listing(self) -> bool:
         with self.log():
@@ -207,14 +202,6 @@ async def delete(self, key: str) -> None:
         with self.log(key):
             return await self._store.delete(key=key)
 
-    async def set_partial_values(
-        self, key_start_values: Iterable[tuple[str, int, bytes | bytearray | memoryview]]
-    ) -> None:
-        # docstring inherited
-        keys = ",".join([k[0] for k in key_start_values])
-        with self.log(keys):
-            return await self._store.set_partial_values(key_start_values=key_start_values)
-
     async def list(self) -> AsyncGenerator[str, None]:
         # docstring inherited
         with self.log():
diff --git a/src/zarr/storage/_memory.py b/src/zarr/storage/_memory.py
index 5c12563136..e6076d9669 100644
--- a/src/zarr/storage/_memory.py
+++ b/src/zarr/storage/_memory.py
@@ -32,13 +32,11 @@ class MemoryStore(Store):
     ----------
     supports_writes
     supports_deletes
-    supports_partial_writes
     supports_listing
     """
 
     supports_writes: bool = True
     supports_deletes: bool = True
-    supports_partial_writes: bool = True
     supports_listing: bool = True
 
     _store_dict: MutableMapping[str, Buffer]
@@ -143,12 +141,6 @@ async def delete(self, key: str) -> None:
         except KeyError:
             logger.debug("Key %s does not exist.", key)
 
-    async def set_partial_values(
-        self, key_start_values: Iterable[tuple[str, int, bytes | bytearray | memoryview[int]]]
-    ) -> None:
-        # docstring inherited
-        raise NotImplementedError
-
     async def list(self) -> AsyncIterator[str]:
         # docstring inherited
         for key in self._store_dict:
diff --git a/src/zarr/storage/_obstore.py b/src/zarr/storage/_obstore.py
index e1469a991e..6bf60655c6 100644
--- a/src/zarr/storage/_obstore.py
+++ b/src/zarr/storage/_obstore.py
@@ -196,17 +196,6 @@ async def delete(self, key: str) -> None:
         with contextlib.suppress(FileNotFoundError):
             await obs.delete_async(self.store, key)
 
-    @property
-    def supports_partial_writes(self) -> bool:
-        # docstring inherited
-        return False
-
-    async def set_partial_values(
-        self, key_start_values: Iterable[tuple[str, int, BytesLike]]
-    ) -> None:
-        # docstring inherited
-        raise NotImplementedError
-
     @property
     def supports_listing(self) -> bool:
         # docstring inherited
diff --git a/src/zarr/storage/_wrapper.py b/src/zarr/storage/_wrapper.py
index f21d378191..dccdd35f8d 100644
--- a/src/zarr/storage/_wrapper.py
+++ b/src/zarr/storage/_wrapper.py
@@ -119,15 +119,6 @@ def supports_deletes(self) -> bool:
     async def delete(self, key: str) -> None:
         await self._store.delete(key)
 
-    @property
-    def supports_partial_writes(self) -> bool:
-        return self._store.supports_partial_writes
-
-    async def set_partial_values(
-        self, key_start_values: Iterable[tuple[str, int, BytesLike]]
-    ) -> None:
-        return await self._store.set_partial_values(key_start_values)
-
     @property
     def supports_listing(self) -> bool:
         return self._store.supports_listing
diff --git a/src/zarr/storage/_zip.py b/src/zarr/storage/_zip.py
index e52f160860..72bf9e335a 100644
--- a/src/zarr/storage/_zip.py
+++ b/src/zarr/storage/_zip.py
@@ -48,7 +48,6 @@ class ZipStore(Store):
     allowed_exceptions
     supports_writes
     supports_deletes
-    supports_partial_writes
     supports_listing
     path
     compression
@@ -57,7 +56,6 @@ class ZipStore(Store):
 
     supports_writes: bool = True
     supports_deletes: bool = False
-    supports_partial_writes: bool = False
     supports_listing: bool = True
 
     path: Path
@@ -222,11 +220,6 @@ async def set(self, key: str, value: Buffer) -> None:
         with self._lock:
             self._set(key, value)
 
-    async def set_partial_values(
-        self, key_start_values: Iterable[tuple[str, int, bytes | bytearray | memoryview[int]]]
-    ) -> None:
-        raise NotImplementedError
-
     async def set_if_not_exists(self, key: str, value: Buffer) -> None:
         self._check_writable()
         with self._lock:
diff --git a/src/zarr/testing/stateful.py b/src/zarr/testing/stateful.py
index 8ada53a55a..c363c13983 100644
--- a/src/zarr/testing/stateful.py
+++ b/src/zarr/testing/stateful.py
@@ -467,17 +467,10 @@ def list_dir(self, prefix: str) -> None:
     def list_prefix(self, prefix: str) -> None:
         raise NotImplementedError
 
-    def set_partial_values(self, key_start_values: Any) -> None:
-        raise NotImplementedError
-
     @property
     def supports_listing(self) -> bool:
         return self.store.supports_listing
 
-    @property
-    def supports_partial_writes(self) -> bool:
-        return self.supports_partial_writes
-
     @property
     def supports_writes(self) -> bool:
         return self.store.supports_writes
diff --git a/src/zarr/testing/store.py b/src/zarr/testing/store.py
index d2946705f0..ad3b80da41 100644
--- a/src/zarr/testing/store.py
+++ b/src/zarr/testing/store.py
@@ -68,8 +68,8 @@ def test_store_repr(self, store: S) -> None: ...
     @abstractmethod
     def test_store_supports_writes(self, store: S) -> None: ...
 
-    @abstractmethod
-    def test_store_supports_partial_writes(self, store: S) -> None: ...
+    def test_store_supports_partial_writes(self, store: S) -> None:
+        assert not store.supports_partial_writes
 
     @abstractmethod
     def test_store_supports_listing(self, store: S) -> None: ...
diff --git a/tests/test_store/test_fsspec.py b/tests/test_store/test_fsspec.py
index 82a96b5d1e..e970c674d4 100644
--- a/tests/test_store/test_fsspec.py
+++ b/tests/test_store/test_fsspec.py
@@ -169,9 +169,6 @@ def test_store_repr(self, store: FsspecStore) -> None:
     def test_store_supports_writes(self, store: FsspecStore) -> None:
         assert store.supports_writes
 
-    def test_store_supports_partial_writes(self, store: FsspecStore) -> None:
-        assert not store.supports_partial_writes
-
     def test_store_supports_listing(self, store: FsspecStore) -> None:
         assert store.supports_listing
 
diff --git a/tests/test_store/test_local.py b/tests/test_store/test_local.py
index 970bb7d374..d7cf8a75ff 100644
--- a/tests/test_store/test_local.py
+++ b/tests/test_store/test_local.py
@@ -38,9 +38,6 @@ def test_store_repr(self, store: LocalStore) -> None:
     def test_store_supports_writes(self, store: LocalStore) -> None:
         assert store.supports_writes
 
-    def test_store_supports_partial_writes(self, store: LocalStore) -> None:
-        assert store.supports_partial_writes
-
     def test_store_supports_listing(self, store: LocalStore) -> None:
         assert store.supports_listing
 
diff --git a/tests/test_store/test_logging.py b/tests/test_store/test_logging.py
index 1a89dca874..d99ac5dc4f 100644
--- a/tests/test_store/test_logging.py
+++ b/tests/test_store/test_logging.py
@@ -44,9 +44,6 @@ def store(self, store_kwargs: str | dict[str, Buffer] | None) -> LoggingStore:
     def test_store_supports_writes(self, store: LoggingStore) -> None:
         assert store.supports_writes
 
-    def test_store_supports_partial_writes(self, store: LoggingStore) -> None:
-        assert store.supports_partial_writes
-
     def test_store_supports_listing(self, store: LoggingStore) -> None:
         assert store.supports_listing
 
diff --git a/tests/test_store/test_memory.py b/tests/test_store/test_memory.py
index 0b6bae757d..29fa9b2964 100644
--- a/tests/test_store/test_memory.py
+++ b/tests/test_store/test_memory.py
@@ -54,9 +54,6 @@ def test_store_supports_writes(self, store: MemoryStore) -> None:
     def test_store_supports_listing(self, store: MemoryStore) -> None:
         assert store.supports_listing
 
-    def test_store_supports_partial_writes(self, store: MemoryStore) -> None:
-        assert store.supports_partial_writes
-
     async def test_list_prefix(self, store: MemoryStore) -> None:
         assert True
 
@@ -115,9 +112,6 @@ def test_store_supports_writes(self, store: GpuMemoryStore) -> None:
     def test_store_supports_listing(self, store: GpuMemoryStore) -> None:
         assert store.supports_listing
 
-    def test_store_supports_partial_writes(self, store: GpuMemoryStore) -> None:
-        assert store.supports_partial_writes
-
     async def test_list_prefix(self, store: GpuMemoryStore) -> None:
         assert True
 
diff --git a/tests/test_store/test_object.py b/tests/test_store/test_object.py
index d8b89e56b7..3217069c2d 100644
--- a/tests/test_store/test_object.py
+++ b/tests/test_store/test_object.py
@@ -48,11 +48,6 @@ def test_store_repr(self, store: ObjectStore) -> None:
     def test_store_supports_writes(self, store: ObjectStore) -> None:
         assert store.supports_writes
 
-    async def test_store_supports_partial_writes(self, store: ObjectStore) -> None:
-        assert not store.supports_partial_writes
-        with pytest.raises(NotImplementedError):
-            await store.set_partial_values([("foo", 0, b"\x01\x02\x03\x04")])
-
     def test_store_supports_listing(self, store: ObjectStore) -> None:
         assert store.supports_listing
 
diff --git a/tests/test_store/test_wrapper.py b/tests/test_store/test_wrapper.py
index c6edd4f4dd..4478e1468f 100644
--- a/tests/test_store/test_wrapper.py
+++ b/tests/test_store/test_wrapper.py
@@ -43,9 +43,6 @@ def open_kwargs(self, tmpdir) -> dict[str, str]:
     def test_store_supports_writes(self, store: WrapperStore) -> None:
         assert store.supports_writes
 
-    def test_store_supports_partial_writes(self, store: WrapperStore) -> None:
-        assert store.supports_partial_writes
-
     def test_store_supports_listing(self, store: WrapperStore) -> None:
         assert store.supports_listing
 
diff --git a/tests/test_store/test_zip.py b/tests/test_store/test_zip.py
index 24b25ed315..744ee82945 100644
--- a/tests/test_store/test_zip.py
+++ b/tests/test_store/test_zip.py
@@ -72,9 +72,6 @@ def test_store_repr(self, store: ZipStore) -> None:
     def test_store_supports_writes(self, store: ZipStore) -> None:
         assert store.supports_writes
 
-    def test_store_supports_partial_writes(self, store: ZipStore) -> None:
-        assert store.supports_partial_writes is False
-
     def test_store_supports_listing(self, store: ZipStore) -> None:
         assert store.supports_listing
 

From 314d45e372c1d6b56ceee1d7778a16c9d384c0b2 Mon Sep 17 00:00:00 2001
From: Stephan Hoyer <shoyer@google.com>
Date: Thu, 28 Aug 2025 10:59:22 -0700
Subject: [PATCH 2/3] ruff fix

---
 src/zarr/abc/store.py        | 1 -
 src/zarr/storage/_fsspec.py  | 1 -
 src/zarr/storage/_obstore.py | 1 -
 src/zarr/storage/_wrapper.py | 1 -
 4 files changed, 4 deletions(-)

diff --git a/src/zarr/abc/store.py b/src/zarr/abc/store.py
index c94ecfdd4b..e8d1329b17 100644
--- a/src/zarr/abc/store.py
+++ b/src/zarr/abc/store.py
@@ -12,7 +12,6 @@
     from typing import Any, Self, TypeAlias
 
     from zarr.core.buffer import Buffer, BufferPrototype
-    from zarr.core.common import BytesLike
 
 __all__ = ["ByteGetter", "ByteSetter", "Store", "set_or_delete"]
 
diff --git a/src/zarr/storage/_fsspec.py b/src/zarr/storage/_fsspec.py
index cb6b4f55ed..3e85a1891c 100644
--- a/src/zarr/storage/_fsspec.py
+++ b/src/zarr/storage/_fsspec.py
@@ -26,7 +26,6 @@
     from fsspec.mapping import FSMap
 
     from zarr.core.buffer import BufferPrototype
-    from zarr.core.common import BytesLike
 
 
 ALLOWED_EXCEPTIONS: tuple[type[Exception], ...] = (
diff --git a/src/zarr/storage/_obstore.py b/src/zarr/storage/_obstore.py
index 6bf60655c6..9bf1df8d8c 100644
--- a/src/zarr/storage/_obstore.py
+++ b/src/zarr/storage/_obstore.py
@@ -23,7 +23,6 @@
     from obstore.store import ObjectStore as _UpstreamObjectStore
 
     from zarr.core.buffer import Buffer, BufferPrototype
-    from zarr.core.common import BytesLike
 
 __all__ = ["ObjectStore"]
 
diff --git a/src/zarr/storage/_wrapper.py b/src/zarr/storage/_wrapper.py
index dccdd35f8d..ba300a4085 100644
--- a/src/zarr/storage/_wrapper.py
+++ b/src/zarr/storage/_wrapper.py
@@ -9,7 +9,6 @@
 
     from zarr.abc.store import ByteRequest
     from zarr.core.buffer import Buffer, BufferPrototype
-    from zarr.core.common import BytesLike
 
 from zarr.abc.store import Store
 

From 6cd571ff8ad19d60cb554f1a1317974b399786e4 Mon Sep 17 00:00:00 2001
From: Stephan Hoyer <shoyer@google.com>
Date: Thu, 28 Aug 2025 11:05:01 -0700
Subject: [PATCH 3/3] include fsspec

---
 src/zarr/storage/_fsspec.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/zarr/storage/_fsspec.py b/src/zarr/storage/_fsspec.py
index 3e85a1891c..c5afed521c 100644
--- a/src/zarr/storage/_fsspec.py
+++ b/src/zarr/storage/_fsspec.py
@@ -89,7 +89,6 @@ class FsspecStore(Store):
     allowed_exceptions
     supports_writes
     supports_deletes
-    supports_partial_writes
     supports_listing
 
     Raises
@@ -113,7 +112,6 @@ class FsspecStore(Store):
     # based on FSSpec
     supports_writes: bool = True
     supports_deletes: bool = True
-    supports_partial_writes: bool = False
     supports_listing: bool = True
 
     fs: AsyncFileSystem