Struct MitoConfig 

pub struct MitoConfig {

    pub num_workers: usize,
    pub worker_channel_size: usize,
    pub worker_request_batch_size: usize,
    pub manifest_checkpoint_distance: u64,
    pub experimental_manifest_keep_removed_file_count: usize,
    pub experimental_manifest_keep_removed_file_ttl: Duration,
    pub compress_manifest: bool,
    pub max_background_index_builds: usize,
    pub experimental_enable_series_index: bool,
    pub experimental_series_index_max_size: ReadableSize,
    pub experimental_enable_range_index: bool,
    pub experimental_series_index_maintenance_interval: Duration,
    pub experimental_series_index_bucket_width: Duration,
    pub max_background_flushes: usize,
    pub max_background_compactions: usize,
    pub max_background_purges: usize,
    pub experimental_compaction_memory_limit: MemoryLimit,
    pub experimental_compaction_on_exhausted: OnExhaustedPolicy,
    pub experimental_compaction_output_parallelism: usize,
    pub auto_flush_interval: Duration,
    pub global_write_buffer_size: ReadableSize,
    pub global_write_buffer_reject_size: ReadableSize,
    pub default_region_write_buffer_size: ReadableSize,
    pub sst_meta_cache_size: ReadableSize,
    pub vector_cache_size: ReadableSize,
    pub page_cache_size: ReadableSize,
    pub selector_result_cache_size: ReadableSize,
    pub range_result_cache_size: ReadableSize,
    pub prefilter_result_cache_size: ReadableSize,
    pub enable_write_cache: bool,
    pub write_cache_path: String,
    pub write_cache_size: ReadableSize,
    pub write_cache_ttl: Option<Duration>,
    pub preload_index_cache: bool,
    pub index_cache_percent: u8,
    pub enable_refill_cache_on_read: bool,
    pub manifest_cache_size: ReadableSize,
    pub sst_write_buffer_size: ReadableSize,
    pub max_concurrent_scan_files: usize,
    pub allow_stale_entries: bool,
    pub scan_memory_limit: MemoryLimit,
    pub scan_memory_mode: ScanMemoryMode,
    pub scan_memory_on_exhausted: OnExhaustedPolicy,
    pub index: IndexConfig,
    pub inverted_index: InvertedIndexConfig,
    pub fulltext_index: FulltextIndexConfig,
    pub bloom_filter_index: BloomFilterConfig,
    pub min_compaction_interval: Duration,
    pub schedule_compaction_after_edit: bool,
    pub default_flat_format: bool,
    pub experimental_series_scan_v2: bool,
    pub gc: GcConfig,
}

Configuration for MitoEngine. Before using the config, call MitoConfig::sanitize() to validate and normalize it.

Fields

num_workers: usize

Number of region workers (default: 1/2 of cpu cores). Sets to 0 to use the default value.

worker_channel_size: usize

Request channel size of each worker (default 128).

worker_request_batch_size: usize

Max batch size for a worker to handle requests (default 64).

manifest_checkpoint_distance: u64

Number of meta action updated to trigger a new checkpoint for the manifest (default 10).

experimental_manifest_keep_removed_file_count: usize

Number of removed files to keep in manifest’s removed_files field before also remove them from removed_files. Mostly for debugging purpose. If set to 0, it will only use keep_removed_file_ttl to decide when to remove files from removed_files field.

experimental_manifest_keep_removed_file_ttl: Duration

How long to keep removed files in the removed_files field of manifest after they are removed from manifest. files will only be removed from removed_files field if both keep_removed_file_count and keep_removed_file_ttl is reached.

compress_manifest: bool

Whether to compress manifest and checkpoint file by gzip (default false).

max_background_index_builds: usize

Max number of running background index build jobs (default: 1/8 of cpu cores).

experimental_enable_series_index: bool

Under development; do not enable. Whether to enable series indexes (default false). Indexes are stored on the local filesystem under {data_home}/series_index.

experimental_series_index_max_size: ReadableSize

Approximate series and range index size limit in open regions (default: 5 GiB). Workers share a periodically refreshed estimate and skip maintenance when full. In-flight reconciliation can exceed the limit; closed-region files are not counted.

experimental_enable_range_index: bool

Whether to build and query range indexes when series indexes are enabled (default false). Obsolete range-index metadata and files are still cleaned up when disabled.

experimental_series_index_maintenance_interval: Duration

Interval between series-index maintenance runs (default 5 min). Zero uses the default.

experimental_series_index_bucket_width: Duration

Under development; do not enable. Requested minimum bucket width for series indexes. It is rounded up to an exact multiple of each region’s compaction time window.

max_background_flushes: usize

Max number of running background flush jobs (default: 1/2 of cpu cores).

max_background_compactions: usize

Max number of running background compaction jobs (default: 1/4 of cpu cores).

The limit applies to the whole engine, not to each region worker. SST compaction and background bulk memtable compaction each have their own budget of this size. For SST compaction, the same limit bounds engine-wide admission of local compaction units and the merge-output budget of each automatic per-region pick. Outputs sharing inputs form one unit. Expired SSTs may add one expiration-only unit outside the merge-output budget; it still consumes a slot in the same admission limit. Manual compaction keeps using the request’s parallelism.

max_background_purges: usize

Max number of running background purge jobs (default: number of cpu cores).

experimental_compaction_memory_limit: MemoryLimit

Memory budget for compaction tasks. Supports absolute size (e.g., “2GiB”, “512MB”) or percentage of system memory (e.g., “50%”). Setting it to 0 or “unlimited” disables the limit.

experimental_compaction_on_exhausted: OnExhaustedPolicy

Behavior when compaction cannot acquire memory from the budget.

experimental_compaction_output_parallelism: usize

Default per-output parallelism for input decoding and SST column encoding, bounded independently per stage. Values below 2 disable both. Tables can override it with compaction.experimental_output_parallelism.

auto_flush_interval: Duration

Interval to auto flush a region if it has not flushed yet (default 10 min).

global_write_buffer_size: ReadableSize

Global write buffer size threshold to trigger flush.

global_write_buffer_reject_size: ReadableSize

Global write buffer size threshold to reject write requests.

default_region_write_buffer_size: ReadableSize

Default write buffer size for each region. Regions stall at this size and reject writes at twice this size. Setting it to 0 disables both limits unless the table specifies write_buffer_size.

sst_meta_cache_size: ReadableSize

Cache size for SST metadata. Setting it to 0 to disable the cache.

vector_cache_size: ReadableSize

Cache size for vectors and arrow arrays. Setting it to 0 to disable the cache.

page_cache_size: ReadableSize

Cache size for pages of SST row groups. Setting it to 0 to disable the cache.

selector_result_cache_size: ReadableSize

Cache size for time series selector (e.g. last_value()). Setting it to 0 to disable the cache.

range_result_cache_size: ReadableSize

Cache size for flat range scan results. Setting it to 0 to disable the cache.

prefilter_result_cache_size: ReadableSize

Cache size for prefilter results. Setting it to 0 to disable the cache.

enable_write_cache: bool

Whether to enable the write cache.

write_cache_path: String

File system path for write cache dir’s root, defaults to {data_home}.

write_cache_size: ReadableSize

Capacity for write cache.

write_cache_ttl: Option<Duration>

TTL for write cache.

preload_index_cache: bool

Preload index (puffin) files into cache on region open (default: true).

index_cache_percent: u8

Percentage of write cache capacity allocated for index (puffin) files (default: 20). The remaining capacity is used for data (parquet) files. Must be between 0 and 100 (exclusive).

enable_refill_cache_on_read: bool

Enable background downloading of files to the local cache when accessed during queries (default: true). When enabled, files will be asynchronously downloaded to improve performance for subsequent reads.

manifest_cache_size: ReadableSize

Capacity for manifest cache (default: 256MB).

sst_write_buffer_size: ReadableSize

Buffer size for SST writing.

max_concurrent_scan_files: usize

Maximum number of SST files to scan concurrently when memory accounting does not cover the scan or the limit is disabled (default 384).

allow_stale_entries: bool

Whether to allow stale entries read during replay.

scan_memory_limit: MemoryLimit

Memory limit for table scans across all queries (default: 25% of system memory). Setting it to 0 or “unlimited” disables the limit. Supports absolute size (e.g., “2GB”) or percentage of system memory (e.g., “50%”).

scan_memory_mode: ScanMemoryMode

Scan memory accounting: basic counts projected Parquet row groups; extended also counts cumulative streamed batches. Limited reservations round up to KB. Internal series merges use the query runtime pool in both modes.

scan_memory_on_exhausted: OnExhaustedPolicy

Scan memory exhaustion always fails immediately (default: fail). Legacy wait and wait(<duration>) values are accepted but deprecated: sanitization warns and replaces them with [OnExhaustedPolicy::Fail].

index: IndexConfig

Index configs.

inverted_index: InvertedIndexConfig

Inverted index configs.

fulltext_index: FulltextIndexConfig

Full-text index configs.

bloom_filter_index: BloomFilterConfig

Bloom filter index configs.

min_compaction_interval: Duration

Minimum time interval between two compactions. To align with the old behavior, the default value is 0 (no restrictions).

schedule_compaction_after_edit: bool

Whether to schedule compaction after applying a region edit.

default_flat_format: bool

Whether to enable flat format as the default SST format. When enabled, forces using BulkMemtable and BulkMemtableBuilder.

experimental_series_scan_v2: bool

Whether to enable the experimental two-phase mode for eligible metric series scans.

gc: GcConfig

Implementations

impl MitoConfig

pub fn sanitize(&mut self, data_home: &str) -> Result<()>

Sanitize incorrect configurations.

Returns an error if there is a configuration that unable to sanitize.

fn adjust_buffer_and_cache_size(&mut self, sys_memory: ReadableSize)

Trait Implementations

impl Clone for MitoConfig

fn clone(&self) -> MitoConfig

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for MitoConfig

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

Formats the value using the given formatter.

impl Default for MitoConfig

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for MitoConfig

where MitoConfig: Default,

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for MitoConfig

impl From<MitoConfig> for ManifestOpenConfig

fn from(mito_config: MitoConfig) -> Self

Converts to this type from the input type.

impl PartialEq for MitoConfig

fn eq(&self, other: &MitoConfig) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for MitoConfig

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for MitoConfig