# Metrics

> USearch for C++

`#include <usearch/dense_index.hpp>`

## dense_index_t

Owns one dense index; destruction waits for its deferred calls.

```cpp
class dense_index_t
```

## dense_index_t

```cpp
dense_index_t() noexcept=default;
```

```cpp
dense_index_t(dense_index_t && other) noexcept;
```

```cpp
dense_index_t(dense_index_t const &)=delete;
```

## operator=

```cpp
dense_index_t & operator=(dense_index_t && other) noexcept;
```

```cpp
dense_index_t & operator=(dense_index_t const &)=delete;
```

## ~dense_index_t

```cpp
~dense_index_t() noexcept;
```

## reserve

Grows the shards ahead of a number of incoming vectors.

```cpp
outcome reserve(
    usearch_dense_reserve_t arguments,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_read_only_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_read_only_k) The index is an NVMe view.
- [`usearch_status_uninitialized_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_uninitialized_k) No shard is placed.
- [`usearch_status_unknown_kind_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unknown_kind_k) The stored scalar's kits cannot finalize the metric.
- [`usearch_status_config_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_config_mismatch_k) The frozen geometry differs from a shard's, or on VRAM a shard's neighbors live on another device or no walk fits the device.
- [`usearch_status_overflow_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_overflow_k) The capacity passes a shard's ceiling, its ID space, its chunk directory or its key column.

## clear

Erases all entries, keeping the reserved capacity and frozen geometry.

```cpp
outcome clear(
    usearch_dense_clear_t arguments = {},
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_read_only_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_read_only_k) The index is an NVMe view.
- [`usearch_status_contended_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_contended_k) A call in flight, a batch or load holding claims, or a plan holding the index closed.

## insert

Adds a run of vectors under their keys, all or nothing per call.

```cpp
outcome insert(
    usearch_dense_insert_t arguments,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_read_only_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_read_only_k) The index is a view.
- [`usearch_status_contended_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_contended_k) A refinement, absorption or clear holds the index, or on VRAM a save or another insertion does; nothing written.

## refine

Refines the graph, answering its report: the nodes re-selected and changed, and the islands found and reconnected.

```cpp
outcome<usearch_refine_report_t> refine(
    usearch_dense_refine_t arguments = {},
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_device_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_device_k) `executor` 's kind does not match the residency.
- [`usearch_status_read_only_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_read_only_k) The index is an NVMe view.
- [`usearch_status_uninitialized_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_uninitialized_k) No shard is placed or froze its geometry, `executor` holds no threads, or a VRAM index keeps such an earlier failure.
- [`usearch_status_contended_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_contended_k) An insertion, load, save, refinement or absorption holds the index, or another call holds `executor` or its pool.
- [`usearch_status_config_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_config_mismatch_k) `executor` drives no stream on some VRAM shard's device, or a VRAM index keeps such an earlier failure.
- [`usearch_status_overflow_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_overflow_k) A queue capacity wraps when rounded, or a VRAM index keeps an earlier overflow.
- [`usearch_status_unsupported_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_k) or [`usearch_status_unsupported_layout_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_layout_k) A VRAM index keeps such an earlier failure.

## health

Audits how much of the graph a search can reach.

```cpp
outcome<usearch_reachability_t> health(
    usearch_dense_health_t arguments = {},
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_device_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_device_k) `executor` 's kind does not match the residency.
- [`usearch_status_uninitialized_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_uninitialized_k) No shard is placed, `executor` holds no pool workers or streams, or a VRAM index keeps such an earlier failure.
- [`usearch_status_contended_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_contended_k) Another call holds `executor` or its pool, or a destructive window overlapped the audit twice.
- [`usearch_status_config_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_config_mismatch_k) `executor` drives no stream on some VRAM shard's device, an NVMe medium the engines cannot read, or a VRAM index keeps such an earlier failure.
- [`usearch_status_overflow_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_overflow_k) A VRAM index keeps an earlier overflow.
- [`usearch_status_unsupported_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_k) or [`usearch_status_unsupported_layout_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_layout_k) A VRAM index keeps such an earlier failure.

## absorb

Absorbs the donor indexes `arguments` names into this one, consuming them.

```cpp
outcome absorb(
    usearch_dense_absorb_t arguments,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_read_only_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_read_only_k) The index is an NVMe view.
- [`usearch_status_invalid_argument_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_invalid_argument_k) A `NULL` donor slot, or `NULL` donors for a nonzero count.
- [`usearch_status_config_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_config_mismatch_k) A donor of another residency, scalar, class, metric or geometry, a donor on a device the executor does not drive, or this index itself.
- [`usearch_status_contended_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_contended_k) An insertion in flight on this index or on the next donor, or on VRAM a save of either; that donor and every later one stay live indexes.

## search

Finds the nearest entries of every query `arguments` names, written into `arena`.

```cpp
outcome<usearch_matches_view_t> search(
    usearch_dense_search_t arguments,
    arena_t const & arena,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_unknown_kind_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unknown_kind_k) A traversal other than a walk or a scan.
- [`usearch_status_unsupported_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_k) A scan of an AMD or Apple VRAM index, or a predicate on any VRAM index.

## count

Answers how many entries `arguments.key` holds.

```cpp
outcome<std::size_t> count(
    usearch_dense_count_t arguments,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_device_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_device_k) `executor` 's kind does not match the residency.
- [`usearch_status_uninitialized_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_uninitialized_k) `executor` holds no pool workers.
- [`usearch_status_contended_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_contended_k) Another call holds `executor`, or its pool runs another dispatch.
- [`usearch_status_config_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_config_mismatch_k) An NVMe medium the engines cannot read.

## get

Answers the vectors `arguments.key` holds; `arguments.written` counts them when the caller sets it.

```cpp
outcome<usearch_rows_view_t> get(
    usearch_dense_get_t arguments,
    arena_t const & arena,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_unknown_kind_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unknown_kind_k) An unknown output scalar.
- [`usearch_status_shape_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_shape_mismatch_k) Sub-byte rows ending inside a byte.
- [`usearch_status_invalid_argument_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_invalid_argument_k) An empty `arena`.
- [`usearch_status_device_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_device_k) An arena or an executor on another residency or device.
- [`usearch_status_contended_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_contended_k) `arena` serves another call, another call holds `executor` or its pool, or a destructive window overlapped the read twice.
- [`usearch_status_uninitialized_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_uninitialized_k) `executor` holds no pool workers, or a VRAM index has no shards.
- [`usearch_status_config_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_config_mismatch_k) `executor` drives no stream on some shard's device, or an NVMe medium the engines cannot read.

## cursor_init

Opens a cursor over every entry of the index.

```cpp
outcome<dense_cursor_t> cursor_init(
    usearch_dense_cursor_init_t arguments = {}) noexcept;
```

Statuses: - [`usearch_status_invalid_argument_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_invalid_argument_k) `NULL` starts for a nonzero count of them.

## cursor_next

Answers the next keys `cursor` walks to; the entries and their count land where the caller points.

```cpp
outcome<usearch_keys_view_t> cursor_next(
    dense_cursor_t const & cursor,
    usearch_dense_cursor_next_t arguments,
    arena_t const & arena,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_invalid_argument_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_invalid_argument_k) `cursor` was opened on another index.

## search_stream_init

Opens a stream of matches that later calls extend.

```cpp
outcome<dense_search_stream_t> search_stream_init(
    usearch_dense_search_stream_init_t arguments) noexcept;
```

Statuses: - [`usearch_status_unsupported_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_k) No residency implements the stream yet.

## search_stream_next

Answers the next matches of `stream`, writing them into `arena`.

```cpp
outcome<usearch_matches_view_t> search_stream_next(
    dense_search_stream_t const & stream,
    usearch_dense_search_stream_next_t arguments,
    arena_t const & arena,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_invalid_argument_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_invalid_argument_k) `stream` was opened on another index.

## save

Writes the index to the checkpoint path `arguments` names.

```cpp
outcome save(
    usearch_dense_save_t arguments,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_contended_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_contended_k) A RAM save meeting an insertion in flight or one publishing under it, or a VRAM save meeting an insertion, refinement, absorption or another save in flight.

## save_buffer

Writes the index into one monolith in `arena`.

```cpp
outcome<usearch_bytes_view_t> save_buffer(
    usearch_dense_save_buffer_t arguments,
    arena_t const & arena,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_invalid_argument_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_invalid_argument_k) An empty `arena`.
- [`usearch_status_device_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_device_k) An arena or an executor on another residency or device.
- [`usearch_status_contended_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_contended_k) `arena` serves another call, another call holds `executor` or its pool, a dispensed batch has yet to publish, or a call, batch, load or plan holds the index.
- [`usearch_status_unsupported_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_k) The index is an NVMe view, which already is its checkpoint.
- [`usearch_status_uninitialized_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_uninitialized_k) No shard is placed or froze its geometry, or `executor` holds no pool workers.
- [`usearch_status_unknown_kind_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unknown_kind_k) The stored scalar has no interchange dtype.
- [`usearch_status_config_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_config_mismatch_k) `executor` drives no stream on some VRAM shard's device.

## multiply

Answers the products; their count and the width they needed land where the caller points.

```cpp
outcome<usearch_matches_tape_view_t> multiply(
    usearch_dense_multiply_t arguments,
    arena_t const & arena,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_unknown_kind_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unknown_kind_k) A traversal other than a walk or a scan.
- [`usearch_status_unsupported_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_k) A scan, or a predicate on a VRAM index.

## attend

Attends the query heads `arguments` names over the entries their walks score, writing the rows into `arena`.

```cpp
outcome<usearch_rows_view_t> attend(
    usearch_dense_attend_t arguments,
    arena_t const & arena,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_invalid_argument_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_invalid_argument_k) A `NULL` value lookup.
- [`usearch_status_shape_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_shape_mismatch_k) The head count does not divide the rows, or a lookup yields a `NULL` row.
- [`usearch_status_unknown_kind_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unknown_kind_k) A traversal other than a walk or a scan.
- [`usearch_status_unsupported_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_k) A scan, or a predicate on a VRAM index.

## maxsim

Scores query groups by late interaction against the index, writing the matches into `arena`.

```cpp
outcome<usearch_matches_tape_view_t> maxsim(
    usearch_dense_maxsim_t arguments,
    arena_t const & arena,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_unknown_kind_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unknown_kind_k) A traversal other than a walk or a scan.
- [`usearch_status_shape_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_shape_mismatch_k) A query without rows, or decreasing query offsets.
- [`usearch_status_unsupported_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_k) A scan, a predicate, ragged query offsets or a zero `wanted` on a VRAM index.

## init_ram

Creates an empty RAM index of the geometry `options` freezes.

```cpp
outcome<dense_index_t> init_ram(
    usearch_dense_init_ram_t options) noexcept;
```

Statuses: - [`usearch_status_config_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_config_mismatch_k) Zero `options.dimensions`, dimensions a packed quantization leaves a storage value partly filled by, or a connectivity that is not a power of two.

## init_vram

Creates an empty VRAM index of the geometry `options` freezes, on the devices it names.

```cpp
outcome<dense_index_t> init_vram(
    usearch_dense_init_vram_t options) noexcept;
```

Statuses: - [`usearch_status_config_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_config_mismatch_k) Zero `options.dimensions`, a connectivity that is not a power of two, or on NVIDIA and AMD a geometry whose walks cannot fit the device's shared memory.

## load_ram

Copies a checkpoint into a new, mutable index in host memory.

```cpp
outcome<dense_index_t> load_ram(
    usearch_dense_load_ram_t options,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_invalid_argument_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_invalid_argument_k) An empty path, or a checkpoint or part path that does not parse.
- [`usearch_status_malformed_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_malformed_k) The checkpoint lists no part, or a part, its header or its key column does not parse, or its connectivity or dimensions are unusable.
- [`usearch_status_unknown_kind_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unknown_kind_k) An unknown quantization, a metric its quantization does not score, or a kernel a shard cannot finalize.
- [`usearch_status_unsupported_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_k) A quantization this build leaves out, or a pinned class the CPU does not admit.
- [`usearch_status_uninitialized_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_uninitialized_k) No memory domain to place a shard on, or `executor` holds no pool workers.
- [`usearch_status_config_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_config_mismatch_k) A memory domain refusing a shard, or the checkpoint's geometry, dtypes or metric differ from the shards'.
- [`usearch_status_device_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_device_k) `executor` is not a RAM executor.
- [`usearch_status_contended_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_contended_k) Another call holds `executor`, or its pool runs another dispatch.
- [`usearch_status_overflow_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_overflow_k) A part passes a shard's bound, a key column or the locator map.

## load_vram

Copies a checkpoint into a new, mutable index in device memory.

```cpp
outcome<dense_index_t> load_vram(
    usearch_dense_load_vram_t options,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_invalid_argument_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_invalid_argument_k) An empty path, or a checkpoint or part path that does not parse.
- [`usearch_status_malformed_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_malformed_k) The checkpoint lists no part, or a part, its header or its key column does not parse, or its connectivity or dimensions are unusable.
- [`usearch_status_unknown_kind_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unknown_kind_k) An unknown quantization, a metric its quantization does not score, or a kernel a shard cannot finalize.
- [`usearch_status_unsupported_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_k) A quantization this build leaves out, or devices that do not run the pinned class.
- [`usearch_status_config_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_config_mismatch_k) Devices of more than one vendor or generation, `executor` driving no stream on some shard's device, or the checkpoint's geometry, dtypes or metric differing from the shards'.
- [`usearch_status_device_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_device_k) An ordinal past the listing, devices this build carries no kernels for, or an executor that is not a VRAM executor.
- [`usearch_status_contended_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_contended_k) Another call holds `executor`.
- [`usearch_status_overflow_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_overflow_k) A part passes a shard's bound, a key column or the locator map.

## load_ram_buffer

Copies a checkpoint from a memory buffer into a new, mutable index in host memory.

```cpp
outcome<dense_index_t> load_ram_buffer(
    usearch_dense_load_ram_buffer_t options,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_invalid_argument_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_invalid_argument_k) An empty buffer.
- [`usearch_status_malformed_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_malformed_k) The manifest lists no part, or a part, its header or its key column does not parse, or its connectivity or dimensions are unusable.
- [`usearch_status_unknown_kind_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unknown_kind_k) An unknown quantization, a metric its quantization does not score, or a kernel a shard cannot finalize.
- [`usearch_status_unsupported_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_k) A quantization this build leaves out, or a pinned class the CPU does not admit.
- [`usearch_status_uninitialized_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_uninitialized_k) No memory domain to place a shard on, or `executor` holds no pool workers.
- [`usearch_status_config_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_config_mismatch_k) A memory domain refusing a shard, or the checkpoint's geometry, dtypes or metric differ from the shards'.
- [`usearch_status_device_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_device_k) `executor` is not a RAM executor.
- [`usearch_status_contended_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_contended_k) Another call holds `executor`, or its pool runs another dispatch.
- [`usearch_status_overflow_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_overflow_k) A part passes a shard's bound, a key column or the locator map.

## load_vram_buffer

Copies a checkpoint from a memory buffer into a new, mutable index in device memory.

```cpp
outcome<dense_index_t> load_vram_buffer(
    usearch_dense_load_vram_buffer_t options,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_invalid_argument_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_invalid_argument_k) An empty buffer.
- [`usearch_status_malformed_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_malformed_k) The manifest lists no part, or a part, its header or its key column does not parse, or its connectivity or dimensions are unusable.
- [`usearch_status_unknown_kind_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unknown_kind_k) An unknown quantization, a metric its quantization does not score, or a kernel a shard cannot finalize.
- [`usearch_status_unsupported_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_k) A quantization this build leaves out, or devices that do not run the pinned class.
- [`usearch_status_config_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_config_mismatch_k) Devices of more than one vendor or generation, `executor` driving no stream on some shard's device, or the checkpoint's geometry, dtypes or metric differing from the shards'.
- [`usearch_status_device_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_device_k) An ordinal past the listing, devices this build carries no kernels for, or an executor that is not a VRAM executor.
- [`usearch_status_contended_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_contended_k) Another call holds `executor`.
- [`usearch_status_overflow_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_overflow_k) A part passes a shard's bound, a key column or the locator map.

## view_ram

Serves a checkpoint in place through a memory mapping, as a read-only index.

```cpp
outcome<dense_index_t> view_ram(
    usearch_dense_view_ram_t options) noexcept;
```

Statuses: - [`usearch_status_unsupported_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_k) Always, as RAM shards cannot serve a mapping in place yet.

## view_nvme

Serves a checkpoint in place from NVMe drives as a read-only index, every later call reading it through `executor` 's engines.

```cpp
outcome<dense_index_t> view_nvme(
    usearch_dense_view_nvme_t options,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_device_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_device_k) `executor` is not an NVMe executor.
- [`usearch_status_invalid_argument_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_invalid_argument_k) An empty path, `NULL` paths for a nonzero count, or a path that does not parse or names a base off its medium's block.
- [`usearch_status_config_mismatch_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_config_mismatch_k) Parts disagreeing with each other, with the scalar or with the devices named.
- [`usearch_status_unsupported_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unsupported_k) A transport identifier in a build without SPDK, a quantization this build leaves out, or a pinned class the CPU does not admit.
- [`usearch_status_malformed_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_malformed_k) The manifest names no part, or a manifest or header does not parse.
- [`usearch_status_unknown_kind_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_unknown_kind_k) An unknown quantization, a metric its quantization does not score, or a kernel the stored scalar's kits cannot finalize.

## metadata_read

Reads a checkpoint's geometry & metric without loading it.

```cpp
outcome<usearch_dense_metadata_t> metadata_read(
    usearch_dense_metadata_read_t arguments,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_invalid_argument_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_invalid_argument_k) An empty path, or a path that does not parse.
- [`usearch_status_malformed_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_malformed_k) The file is empty, or its manifest or header does not parse.

## metadata_read_buffer

Reads geometry & metric from a serialized checkpoint buffer.

```cpp
outcome<usearch_dense_metadata_t> metadata_read_buffer(
    usearch_dense_metadata_read_buffer_t arguments,
    executor_t const & executor = {}) noexcept;
```

Statuses: - [`usearch_status_invalid_argument_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_invalid_argument_k) An empty buffer.
- [`usearch_status_malformed_k`](https://www.unum.cloud/docs/usearch/c/errors.md#usearch_status_malformed_k) The manifest or the header does not parse.