Struct SeqScan

pub struct SeqScan {
    properties: ScannerProperties,
    stream_ctx: Arc<StreamContext>,
    compaction: bool,
    metrics_list: PartitionMetricsList,
}

Scans a region and returns rows in a sorted sequence.

The output order is always order by primary keys, time index inside every PartitionRange. Each “partition” may contains many PartitionRanges.

Fields

properties: ScannerProperties

Properties of the scanner.

stream_ctx: Arc<StreamContext>

Context of streams.

compaction: bool

The scanner is used for compaction.

metrics_list: PartitionMetricsList

Metrics for each partition. The scanner only sets in query and keeps it empty during compaction.

Implementations

impl SeqScan

pub(crate) fn new(input: ScanInput, compaction: bool) -> Self

Creates a new SeqScan with the given input and compaction flag. If compaction is true, the scanner will not attempt to split ranges.

pub fn build_stream(&self) -> Result<SendableRecordBatchStream, BoxedError>

Builds a stream for the query.

The returned stream is not partitioned and will contains all the data. If want partitioned scan, use RegionScanner::scan_partition.

pub async fn build_reader_for_compaction(&self) -> Result<BoxedBatchReader>

Builds a BoxedBatchReader from sequential scan for compaction.

Panics

Panics if the compaction flag is not set.

async fn merge_all_ranges_for_compaction( stream_ctx: &Arc<StreamContext>, partition_ranges: &[PartitionRange], part_metrics: &PartitionMetrics, ) -> Result<BoxedBatchReader>

Builds a merge reader that reads all ranges. Callers MUST not split ranges before calling this method.

async fn build_reader_from_sources( stream_ctx: &StreamContext, sources: Vec<Source>, semaphore: Option<Arc<Semaphore>>, ) -> Result<BoxedBatchReader>

Builds a reader to read sources. If semaphore is provided, reads sources in parallel if possible.

fn scan_partition_impl( &self, metrics_set: &ExecutionPlanMetricsSet, partition: usize, ) -> Result<SendableRecordBatchStream, BoxedError>

Scans the given partition when the part list is set properly. Otherwise the returned stream might not contains any data.

fn scan_partition_by_series( &self, metrics_set: &ExecutionPlanMetricsSet, partition: usize, ) -> Result<SendableRecordBatchStream, BoxedError>

Scans all ranges in the given partition and merge by time series. Otherwise the returned stream might not contains any data.

fn new_semaphore(&self) -> Option<Arc<Semaphore>>

fn new_partition_metrics( &self, metrics_set: &ExecutionPlanMetricsSet, partition: usize, ) -> PartitionMetrics

Creates a new partition metrics instance. Sets the partition metrics for the given partition if it is not for compaction.

Trait Implementations

impl Debug for SeqScan

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

Formats the value using the given formatter.

impl DisplayAs for SeqScan

fn fmt_as(&self, t: DisplayFormatType, f: &mut Formatter<'_>) -> Result

Format according to DisplayFormatType, used when verbose representation looks different from the default one

impl RegionScanner for SeqScan

fn properties(&self) -> &ScannerProperties

Returns the properties of the scanner.

fn schema(&self) -> SchemaRef

Returns the schema of the record batches.

fn metadata(&self) -> RegionMetadataRef

Returns the metadata of the region.

fn scan_partition( &self, metrics_set: &ExecutionPlanMetricsSet, partition: usize, ) -> Result<SendableRecordBatchStream, BoxedError>

Scans the partition and returns a stream of record batches.

fn prepare(&mut self, request: PrepareRequest) -> Result<(), BoxedError>

Prepares the scanner with the given partition ranges.

fn has_predicate(&self) -> bool

Check if there is any predicate that may be executed in this scanner.

fn set_logical_region(&mut self, logical_region: bool)

Sets whether the scanner is reading a logical region.