Package org.apache.iceberg

Interface ScanTaskGroup<T extends ScanTask>

Type Parameters:

T - the type of scan tasks

All Superinterfaces:

ScanTask, java.io.Serializable

All Known Subinterfaces:

CombinedScanTask

All Known Implementing Classes:

BaseCombinedScanTask, BaseScanTaskGroup

public interface ScanTaskGroup<T extends ScanTask>
extends ScanTask

A scan task that may include partial input files, multiple input files or both.

Method Summary

Modifier and Type	Method	Description
default long	estimatedRowsCount()	The estimated number of rows produced by this scan task.
default int	filesCount()	The number of files that will be opened by this scan task.
default StructLike	groupingKey()	Returns a grouping key for this task group.
default long	sizeBytes()	The number of bytes that should be read by this scan task.
java.util.Collection<T>	tasks()	Returns scan tasks in this group.

Methods inherited from interface org.apache.iceberg.ScanTask

asCombinedScanTask, asDataTask, asFileScanTask, isDataTask, isFileScanTask

Method Detail

groupingKey

default StructLike groupingKey()

Returns a grouping key for this task group.

A grouping key is a set of values that are common amongst all rows produced by the tasks in this task group. The values may be the result of transforming the underlying data. For example, a grouping key can consist of a bucket ordinal computed by applying a bucket transform to a column of the underlying rows. The grouping key type is determined at planning time and is identical across all task groups produced by a scan.

Implementations should return an empty struct if the data grouping is random or unknown.

Returns:

a grouping key for this task group

tasks

java.util.Collection<T> tasks()

Returns scan tasks in this group.

sizeBytes

default long sizeBytes()

Description copied from interface: ScanTask

The number of bytes that should be read by this scan task.

Specified by:

sizeBytes in interface ScanTask

Returns:

the total number of bytes to read

estimatedRowsCount

default long estimatedRowsCount()

Description copied from interface: ScanTask

The estimated number of rows produced by this scan task.

Specified by:

estimatedRowsCount in interface ScanTask

Returns:

the estimated number of produced rows

filesCount

default int filesCount()

Description copied from interface: ScanTask

The number of files that will be opened by this scan task.

Specified by:

filesCount in interface ScanTask

Returns:

the number of files to open