Package org.apache.iceberg

Class SparkDistributedDataScan

  • All Implemented Interfaces:
    BatchScan, Scan<BatchScan,​ScanTask,​ScanTaskGroup<ScanTask>>
    public class SparkDistributedDataScan
extends SnapshotScan<ThisT,​T,​G>
    A batch data scan that can utilize Spark cluster resources for planning.

    This scan remotely filters manifests, fetching only the relevant data and delete files to the driver. The delete file assignment is done locally after the remote filtering step. Such approach is beneficial if the remote parallelism is much higher than the number of driver cores.

    This scan is best suited for queries with selective filters on lower/upper bounds across all partitions, or against poorly clustered metadata. This allows job planning to benefit from highly concurrent remote filtering while not incurring high serialization and data transfer costs. This class is also useful for full table scans over large tables but the cost of bringing data and delete file details to the driver may become noticeable. Make sure to follow the performance tips below in such cases.

    Ensure the filtered metadata size doesn't exceed the driver's max result size. For large table scans, consider increasing `spark.driver.maxResultSize` to avoid job failures.

    Performance tips:

    • Enable Kryo serialization (`spark.serializer`)
    • Increase the number of driver cores (`spark.driver.cores`)
    • Tune the number of threads used to fetch task results (`spark.resultGetter.threads`)

    • Field Detail

      • SCAN_COLUMNS

        protected static final java.util.List<java.lang.String> SCAN_COLUMNS

      • SCAN_WITH_STATS_COLUMNS

        protected static final java.util.List<java.lang.String> SCAN_WITH_STATS_COLUMNS

      • DELETE_SCAN_COLUMNS

        protected static final java.util.List<java.lang.String> DELETE_SCAN_COLUMNS

      • DELETE_SCAN_WITH_STATS_COLUMNS

        protected static final java.util.List<java.lang.String> DELETE_SCAN_WITH_STATS_COLUMNS

      • PLAN_SCANS_WITH_WORKER_POOL

        protected static final boolean PLAN_SCANS_WITH_WORKER_POOL

    • Constructor Detail

      • SparkDistributedDataScan

        public SparkDistributedDataScan​(org.apache.spark.sql.SparkSession spark,
                                Table table,
                                SparkReadConf readConf)

    • Method Detail

      • newRefinedScan

        protected BatchScan newRefinedScan​(Table newTable,
                                   Schema newSchema,
                                   org.apache.iceberg.TableScanContext newContext)

      • remoteParallelism

        protected int remoteParallelism()
        Returns the cluster parallelism.

        This value indicates the maximum number of manifests that can be processed concurrently by the cluster. Implementations should take into account both the currently available processing slots and potential dynamic allocation, if applicable.

        The remote parallelism is compared against the size of the thread pool available locally to determine the feasibility of remote planning. This value is ignored if the planning mode is set explicitly as local or distributed.

      • dataPlanningMode

        protected PlanningMode dataPlanningMode()
        Returns which planning mode to use for data.

      • shouldCopyRemotelyPlannedDataFiles

        protected boolean shouldCopyRemotelyPlannedDataFiles()
        Controls whether defensive copies are created for remotely planned data files.

        By default, this class creates defensive copies for each data file that is planned remotely, assuming the provided iterable can be lazy and may reuse objects. If unnecessary and data file objects can be safely added into a collection, implementations can override this behavior.

      • planDataRemotely

        protected java.lang.Iterable<CloseableIterable<DataFile>> planDataRemotely​(java.util.List<ManifestFile> dataManifests,
                                                                           boolean withColumnStats)
        Plans data remotely.

        Implementations are encouraged to return groups of matching data files, enabling this class to process multiple groups concurrently to speed up the remaining work. This is particularly useful when dealing with equality deletes, as delete index lookups with such delete files require comparing bounds and typically benefit from parallelization.

        If the result iterable reuses objects, shouldCopyRemotelyPlannedDataFiles() must return true.

        The input data manifests have been already filtered to include only potential matches based on the scan filter. Implementations are expected to further filter these manifests and only return files that may hold data matching the scan filter.

        Parameters:
        dataManifests - data manifests that may contain files matching the scan filter
        withColumnStats - a flag whether to load column stats
        Returns:
        groups of data files planned remotely

      • deletePlanningMode

        protected PlanningMode deletePlanningMode()
        Returns which planning mode to use for deletes.

      • planDeletesRemotely

        protected org.apache.iceberg.DeleteFileIndex planDeletesRemotely​(java.util.List<ManifestFile> deleteManifests)
        Plans deletes remotely.

        The input delete manifests have been already filtered to include only potential matches based on the scan filter. Implementations are expected to further filter these manifests and return files that may hold deletes matching the scan filter.

        Parameters:
        deleteManifests - delete manifests that may contain files matching the scan filter
        Returns:
        a delete file index planned remotely

      • newManifestGroup

        protected org.apache.iceberg.ManifestGroup newManifestGroup​(java.util.List<ManifestFile> dataManifests,
                                                            java.util.List<ManifestFile> deleteManifests)

      • newManifestGroup

        protected org.apache.iceberg.ManifestGroup newManifestGroup​(java.util.List<ManifestFile> dataManifests,
                                                            boolean withColumnStats)

      • newManifestGroup

        protected org.apache.iceberg.ManifestGroup newManifestGroup​(java.util.List<ManifestFile> dataManifests,
                                                            java.util.List<ManifestFile> deleteManifests,
                                                            boolean withColumnStats)

      • table

        public Table table()

      • tableSchema

        protected Schema tableSchema()

      • context

        protected org.apache.iceberg.TableScanContext context()

      • options

        protected java.util.Map<java.lang.String,​java.lang.String> options()

      • scanColumns

        protected java.util.List<java.lang.String> scanColumns()

      • shouldReturnColumnStats

        protected boolean shouldReturnColumnStats()

      • columnsToKeepStats

        protected java.util.Set<java.lang.Integer> columnsToKeepStats()

      • shouldIgnoreResiduals

        protected boolean shouldIgnoreResiduals()

      • residualFilter

        protected Expression residualFilter()

      • shouldPlanWithExecutor

        protected boolean shouldPlanWithExecutor()

      • planExecutor

        protected java.util.concurrent.ExecutorService planExecutor()

      • option

        public ThisT option​(java.lang.String property,
                    java.lang.String value)
        Description copied from interface: Scan
        Create a new scan from this scan's configuration that will override the Table's behavior based on the incoming pair. Unknown properties will be ignored.
        Specified by:
        option in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>
        Parameters:
        property - name of the table property to be overridden
        value - value to override with
        Returns:
        a new scan based on this with overridden behavior

      • project

        public ThisT project​(Schema projectedSchema)
        Description copied from interface: Scan
        Create a new scan from this with the schema as its projection.
        Specified by:
        project in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>
        Parameters:
        projectedSchema - a projection schema
        Returns:
        a new scan based on this with the given projection

      • caseSensitive

        public ThisT caseSensitive​(boolean caseSensitive)
        Description copied from interface: Scan
        Create a new scan from this that, if data columns where selected via Scan.select(java.util.Collection), controls whether the match to the schema will be done with case sensitivity. Default is true.
        Specified by:
        caseSensitive in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>
        Returns:
        a new scan based on this with case sensitivity as stated

      • isCaseSensitive

        public boolean isCaseSensitive()
        Description copied from interface: Scan
        Returns whether this scan is case-sensitive with respect to column names.
        Specified by:
        isCaseSensitive in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>
        Returns:
        true if case-sensitive, false otherwise.

      • includeColumnStats

        public ThisT includeColumnStats()
        Description copied from interface: Scan
        Create a new scan from this that loads the column stats with each data file.

        Column stats include: value count, null value count, lower bounds, and upper bounds.

        Specified by:
        includeColumnStats in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>
        Returns:
        a new scan based on this that loads column stats.

      • includeColumnStats

        public ThisT includeColumnStats​(java.util.Collection<java.lang.String> requestedColumns)
        Description copied from interface: Scan
        Create a new scan from this that loads the column stats for the specific columns with each data file.

        Column stats include: value count, null value count, lower bounds, and upper bounds.

        Specified by:
        includeColumnStats in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>
        Parameters:
        requestedColumns - column names for which to keep the stats.
        Returns:
        a new scan based on this that loads column stats for specific columns.

      • select

        public ThisT select​(java.util.Collection<java.lang.String> columns)
        Description copied from interface: Scan
        Create a new scan from this that will read the given data columns. This produces an expected schema that includes all fields that are either selected or used by this scan's filter expression.
        Specified by:
        select in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>
        Parameters:
        columns - column names from the table's schema
        Returns:
        a new scan based on this with the given projection columns

      • filter

        public ThisT filter​(Expression expr)
        Description copied from interface: Scan
        Create a new scan from the results of this filtered by the Expression.
        Specified by:
        filter in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>
        Parameters:
        expr - a filter expression
        Returns:
        a new scan based on this with results filtered by the expression

      • ignoreResiduals

        public ThisT ignoreResiduals()
        Description copied from interface: Scan
        Create a new scan from this that applies data filtering to files but not to rows in those files.
        Specified by:
        ignoreResiduals in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>
        Returns:
        a new scan based on this that does not filter rows in files.

      • planWith

        public ThisT planWith​(java.util.concurrent.ExecutorService executorService)
        Description copied from interface: Scan
        Create a new scan to use a particular executor to plan. The default worker pool will be used by default.
        Specified by:
        planWith in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>
        Parameters:
        executorService - the provided executor
        Returns:
        a table scan that uses the provided executor to access manifests

      • schema

        public Schema schema()
        Description copied from interface: Scan
        Returns this scan's projection Schema.

        If the projection schema was set directly using Scan.project(Schema), returns that schema.

        If the projection schema was set by calling Scan.select(Collection), returns a projection schema that includes the selected data fields and any fields used in the filter expression.

        Specified by:
        schema in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>
        Returns:
        this scan's projection schema

      • targetSplitSize

        public long targetSplitSize()
        Description copied from interface: Scan
        Returns the target split size for this scan.
        Specified by:
        targetSplitSize in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>

      • splitLookback

        public int splitLookback()
        Description copied from interface: Scan
        Returns the split lookback for this scan.
        Specified by:
        splitLookback in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>

      • splitOpenFileCost

        public long splitOpenFileCost()
        Description copied from interface: Scan
        Returns the split open file cost for this scan.
        Specified by:
        splitOpenFileCost in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>

      • metricsReporter

        public ThisT metricsReporter​(MetricsReporter reporter)
        Description copied from interface: Scan
        Create a new scan that will report scan metrics to the provided reporter in addition to reporters maintained by the scan.
        Specified by:
        metricsReporter in interface Scan<ThisT,​T extends ScanTask,​G extends ScanTaskGroup<T>>