Package org.apache.iceberg

Interface Scan<ThisT,T extends ScanTask,G extends ScanTaskGroup<T>>

Type Parameters:
ThisT - the child Java API class, returned by method chaining
T - the Java type of tasks produces by this scan
G - the Java type of task groups produces by this scan
All Known Subinterfaces:
BatchScan, IncrementalAppendScan, IncrementalChangelogScan, IncrementalScan<ThisT,T,G>, TableScan
All Known Implementing Classes:
AllDataFilesTable.AllDataFilesTableScan, AllDeleteFilesTable.AllDeleteFilesTableScan, AllFilesTable.AllFilesTableScan, AllManifestsTable.AllManifestsTableScan, DataFilesTable.DataFilesTableScan, DataTableScan, DeleteFilesTable.DeleteFilesTableScan, FilesTable.FilesTableScan, PositionDeletesTable.PositionDeletesBatchScan, SnapshotScan, SparkDistributedDataScan
public interface Scan<ThisT,T extends ScanTask,G extends ScanTaskGroup<T>>
Scan objects are immutable and can be shared between threads. Refinement methods, like select(Collection) and filter(Expression), create new TableScan instances.

  • Method Details

    • option

      ThisT option(String property, String value)
      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.
      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

      ThisT project(Schema schema)
      Create a new scan from this with the schema as its projection.
      Parameters:
      schema - a projection schema
      Returns:
      a new scan based on this with the given projection

    • caseSensitive

      ThisT caseSensitive(boolean caseSensitive)
      Create a new scan from this that, if data columns where selected via select(java.util.Collection), controls whether the match to the schema will be done with case sensitivity. Default is true.
      Returns:
      a new scan based on this with case sensitivity as stated

    • isCaseSensitive

      boolean isCaseSensitive()
      Returns whether this scan is case-sensitive with respect to column names.
      Returns:
      true if case-sensitive, false otherwise.

    • includeColumnStats

      ThisT includeColumnStats()
      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.

      Returns:
      a new scan based on this that loads column stats.

    • includeColumnStats

      default ThisT includeColumnStats(Collection<String> requestedColumns)
      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.

      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

      ThisT select(Collection<String> columns)
      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.
      Parameters:
      columns - column names from the table's schema
      Returns:
      a new scan based on this with the given projection columns

    • select

      default ThisT select(String... columns)
      Create a new scan from this that will read the given columns. This produces an expected schema that includes all fields that are either selected or used by this scan's filter expression.
      Parameters:
      columns - column names
      Returns:
      a new scan based on this with the given projection columns

    • filter

      ThisT filter(Expression expr)
      Create a new scan from the results of this filtered by the Expression.
      Parameters:
      expr - a filter expression
      Returns:
      a new scan based on this with results filtered by the expression

    • filter

      Expression filter()
      Returns this scan's filter Expression.
      Returns:
      this scan's filter expression

    • ignoreResiduals

      ThisT ignoreResiduals()
      Create a new scan from this that applies data filtering to files but not to rows in those files.
      Returns:
      a new scan based on this that does not filter rows in files.

    • planWith

      ThisT planWith(ExecutorService executorService)
      Create a new scan to use a particular executor to plan. The default worker pool will be used by default.
      Parameters:
      executorService - the provided executor
      Returns:
      a table scan that uses the provided executor to access manifests

    • schema

      Schema schema()
      Returns this scan's projection Schema.

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

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

      Returns:
      this scan's projection schema

    • planFiles

      CloseableIterable<T> planFiles()
      Plan tasks for this scan where each task reads a single file.

      Use planTasks() for planning balanced tasks where each task will read either a single file, a part of a file, or multiple files.

      Returns:
      an Iterable of tasks scanning entire files required by this scan

    • planTasks

      CloseableIterable<G> planTasks()
      Plan balanced task groups for this scan by splitting large and combining small tasks.

      Task groups created by this method may read partial input files, multiple input files or both.

      Returns:
      an Iterable of balanced task groups required by this scan

    • targetSplitSize

      long targetSplitSize()
      Returns the target split size for this scan.

    • splitLookback

      int splitLookback()
      Returns the split lookback for this scan.

    • splitOpenFileCost

      long splitOpenFileCost()
      Returns the split open file cost for this scan.

    • metricsReporter

      default ThisT metricsReporter(MetricsReporter reporter)
      Create a new scan that will report scan metrics to the provided reporter in addition to reporters maintained by the scan.