Struct MetricEngine

pub struct MetricEngine {
    inner: Arc<MetricEngineInner>,
}

Metric Engine

Regions

Regions in this metric engine has several roles. There is PhysicalRegion, which refer to the region that actually stores the data. And LogicalRegion that is “simulated” over physical regions. Each logical region is associated with one physical region group, which is a group of two physical regions. Their relationship is illustrated below:

erDiagram LogicalRegion ||--o{ PhysicalRegionGroup : corresponds PhysicalRegionGroup ||--|| DataRegion : contains PhysicalRegionGroup ||--|| MetadataRegion : contains

Metric engine uses two region groups. One is for data region (METRIC_DATA_REGION_GROUP), and the other is for metadata region (METRIC_METADATA_REGION_GROUP). From the definition of RegionId, we can convert between these two physical region ids easily. Thus in the code base we usually refer to one “physical region id”, and convert it to the other one when necessary.

The logical region, in contrast, is a virtual region. It doesn’t has dedicated storage or region group. Only a region id that is allocated by meta server. And all other things is shared with other logical region that are associated with the same physical region group.

For more document about physical regions, please refer to MetadataRegion and DataRegion.

Operations

Both physical and logical region are accessible to user. But the operation they support are different. List below:

Operations	Logical Region	Physical Region
Create	✅	✅
Drop	✅	❓*
Write	✅	❌
Read	✅	✅
Close	✅	✅
Open	✅	✅
Alter	✅	❓*

*: Physical region can be dropped only when all related logical regions are dropped. *: Alter: Physical regions only support altering region options.

Internal Columns

The physical data region contains two internal columns. Should mention that “internal” here is for metric engine itself. Mito engine will add it’s internal columns to the region as well.

Their column id is registered in [ReservedColumnId]. And column name is defined in [DATA_SCHEMA_TSID_COLUMN_NAME] and [DATA_SCHEMA_TABLE_ID_COLUMN_NAME].

Tsid is generated by hashing all tags. And table id is retrieved from logical region id to distinguish data from different logical tables.

Fields

inner: Arc<MetricEngineInner>

Implementations

impl MetricEngine

pub fn try_new(mito: MitoEngine, config: EngineConfig) -> Result<Self>

pub fn mito(&self) -> MitoEngine

pub async fn logical_regions( &self, physical_region_id: RegionId, ) -> Result<Vec<RegionId>>

Returns all logical regions associated with the physical region.

async fn handle_query( &self, region_id: RegionId, request: ScanRequest, ) -> Result<RegionScannerRef, BoxedError>

Handles substrait query and return a stream of record batches

async fn handle_requests( &self, requests: impl IntoIterator<Item = (RegionId, RegionRequest)>, ) -> Result<RegionResponse, BoxedError>

Trait Implementations

impl Clone for MetricEngine

fn clone(&self) -> MetricEngine

Returns a copy of the value.

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

Performs copy-assignment from source.

impl RegionEngine for MetricEngine

fn name(&self) -> &str

Name of this engine

fn handle_request<'life0, 'async_trait>( &'life0 self, region_id: RegionId, request: RegionRequest, ) -> Pin<Box<dyn Future<Output = Result<RegionResponse, BoxedError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Handles non-query request to the region. Returns the count of affected rows.

fn get_metadata<'life0, 'async_trait>( &'life0 self, region_id: RegionId, ) -> Pin<Box<dyn Future<Output = Result<RegionMetadataRef, BoxedError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Retrieves region’s metadata.

fn region_statistic(&self, region_id: RegionId) -> Option<RegionStatistic>

Retrieves region’s disk usage.

Note: Returns None if it’s a logical region.

fn stop<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Result<(), BoxedError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Stops the engine

fn role(&self, region_id: RegionId) -> Option<RegionRole>

Returns the physical region role.

Note: Returns None if it’s a logical region.

fn handle_batch_open_requests<'life0, 'async_trait>( &'life0 self, parallelism: usize, requests: Vec<(RegionId, RegionOpenRequest)>, ) -> Pin<Box<dyn Future<Output = Result<BatchResponses, BoxedError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Handles batch open region requests.

fn handle_batch_ddl_requests<'life0, 'async_trait>( &'life0 self, batch_request: BatchRegionDdlRequest, ) -> Pin<Box<dyn Future<Output = Result<RegionResponse, BoxedError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

fn handle_query<'life0, 'async_trait>( &'life0 self, region_id: RegionId, request: ScanRequest, ) -> Pin<Box<dyn Future<Output = Result<RegionScannerRef, BoxedError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Handles query and return a scanner that can be used to scan the region concurrently.

fn get_last_seq_num<'life0, 'async_trait>( &'life0 self, region_id: RegionId, ) -> Pin<Box<dyn Future<Output = Result<Option<SequenceNumber>, BoxedError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Returns the last sequence number of the region.

fn set_region_role( &self, region_id: RegionId, role: RegionRole, ) -> Result<(), BoxedError>

Sets RegionRole for a region.

fn sync_region<'life0, 'async_trait>( &'life0 self, region_id: RegionId, manifest_info: RegionManifestInfo, ) -> Pin<Box<dyn Future<Output = Result<SyncManifestResponse, BoxedError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Syncs the region manifest to the given manifest version.

fn set_region_role_state_gracefully<'life0, 'async_trait>( &'life0 self, region_id: RegionId, region_role_state: SettableRegionRoleState, ) -> Pin<Box<dyn Future<Output = Result<SetRegionRoleStateResponse, BoxedError>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Sets region role state gracefully.

fn as_any(&self) -> &dyn Any

fn get_region_sequences<'life0, 'async_trait>( &'life0 self, seqs: RegionSequencesRequest, ) -> Pin<Box<dyn Future<Output = Result<HashMap<u64, u64>, BoxedError>> + Send + 'async_trait>>

where 'life0: 'async_trait, Self: 'async_trait,