Enum MetricEvent 

pub enum MetricEvent {
    LogSegmentLoaded {
        operation_id: MetricId,
        duration: Duration,
        num_commit_files: u64,
        num_checkpoint_files: u64,
        num_compaction_files: u64,
    },
    ProtocolMetadataLoaded {
        operation_id: MetricId,
        duration: Duration,
    },
    SnapshotCompleted {
        operation_id: MetricId,
        version: u64,
        total_duration: Duration,
    },
    SnapshotFailed {
        operation_id: MetricId,
        duration: Duration,
    },
    StorageListCompleted {
        duration: Duration,
        num_files: u64,
    },
    StorageReadCompleted {
        duration: Duration,
        num_files: u64,
        bytes_read: u64,
    },
    StorageCopyCompleted {
        duration: Duration,
    },
    JsonReadCompleted {
        num_files: u64,
        bytes_read: u64,
    },
    ParquetReadCompleted {
        num_files: u64,
        bytes_read: u64,
    },
    ScanMetadataCompleted {
        operation_id: MetricId,
        scan_type: ScanType,
        total_duration: Duration,
        num_add_files_seen: u64,
        num_active_add_files: u64,
        num_remove_files_seen: u64,
        num_non_file_actions: u64,
        num_predicate_filtered: u64,
        peak_hash_set_size: usize,
        dedup_visitor_time_ms: u64,
        predicate_eval_time_ms: u64,
    },
}

Metric events emitted during Delta Kernel operations.

Some events include an operation_id (MetricId) that uniquely identifies the operation instance. This allows correlating multiple events from the same operation.

Variants

LogSegmentLoaded

Log segment loading completed (listing and organizing log files).

Fields

operation_id: MetricId

duration: Duration

num_commit_files: u64

num_checkpoint_files: u64

num_compaction_files: u64

ProtocolMetadataLoaded

Protocol and metadata loading completed.

Fields

operation_id: MetricId

duration: Duration

SnapshotCompleted

Snapshot creation completed successfully.

Fields

operation_id: MetricId

version: u64

total_duration: Duration

SnapshotFailed

Snapshot creation failed.

Fields

operation_id: MetricId

duration: Duration

StorageListCompleted

Storage list operation completed. These events track storage-level latencies and are emitted automatically by the default storage handler implementation.

Fields

duration: Duration

num_files: u64

StorageReadCompleted

Storage read operation completed.

Fields

duration: Duration

num_files: u64

bytes_read: u64

StorageCopyCompleted

Storage copy operation completed.

Fields

duration: Duration

JsonReadCompleted

JSON file read operation completed (one event per JsonHandler::read_json_files call).

bytes_read is the sum of FileMeta::size for the requested files (on-disk size), which is the best available approximation without re-reading the bytes.

Fields

num_files: u64

bytes_read: u64

ParquetReadCompleted

Parquet file read operation completed (one event per ParquetHandler::read_parquet_files call).

bytes_read is the sum of FileMeta::size for the requested files (on-disk size), which is the best available approximation without re-reading the bytes.

Fields

num_files: u64

bytes_read: u64

ScanMetadataCompleted

Scan metadata iteration completed.

Emitted when the scan metadata iterator is exhausted. This event captures metrics about the log replay process, including file counts and timing information.

Fields

operation_id: MetricId

Unique ID to correlate this scan with other events.

scan_type: ScanType

Indicates which scan execution path produced this event.

This is SequentialPhase or ParallelPhase for parallel log replay, and Full for crate::scan::Scan::scan_metadata.

total_duration: Duration

Total duration from scan start to iterator exhaustion.

num_add_files_seen: u64

Add files that entered the deduplication visitor. This excludes files filtered by data skipping before deduplication. For the total number of add actions in the log, this value plus num_predicate_filtered gives a closer approximation.

num_active_add_files: u64

Add files that survived log replay (files to read).

num_remove_files_seen: u64

Remove files seen (from delta/commit files only).

num_non_file_actions: u64

Non-file actions seen (protocol, metadata, etc.).

num_predicate_filtered: u64

Files filtered by predicates (data skipping + partition pruning).

peak_hash_set_size: usize

Peak size of the deduplication hash set.

dedup_visitor_time_ms: u64

Time spent in the deduplication visitor (milliseconds).

predicate_eval_time_ms: u64

Time spent evaluating predicates (milliseconds).

Trait Implementations

impl Clone for MetricEvent

fn clone(&self) -> MetricEvent

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MetricEvent

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for MetricEvent

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.