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

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 Summary

Modifier and Type	Method and Description
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.
Expression	filter() Returns this scan's filter Expression.
ThisT	filter(Expression expr) Create a new scan from the results of this filtered by the Expression.
ThisT	ignoreResiduals() Create a new scan from this that applies data filtering to files but not to rows in those files.
ThisT	includeColumnStats() Create a new scan from this that loads the column stats with each data file.
boolean	isCaseSensitive() Returns whether this scan is case-sensitive with respect to column names.
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.
ThisT	option(java.lang.String property, java.lang.String value) Create a new scan from this scan's configuration that will override the Table's behavior based on the incoming pair.
CloseableIterable<T>	planFiles() Plan tasks for this scan where each task reads a single file.
CloseableIterable<G>	planTasks() Plan balanced task groups for this scan by splitting large and combining small tasks.
ThisT	planWith(java.util.concurrent.ExecutorService executorService) Create a new scan to use a particular executor to plan.
ThisT	project(Schema schema) Create a new scan from this with the schema as its projection.
Schema	schema() Returns this scan's projection Schema.
ThisT	select(java.util.Collection<java.lang.String> columns) Create a new scan from this that will read the given data columns.
default ThisT	select(java.lang.String... columns) Create a new scan from this that will read the given columns.
int	splitLookback() Returns the split lookback for this scan.
long	splitOpenFileCost() Returns the split open file cost for this scan.
long	targetSplitSize() Returns the target split size for this scan.

Method Detail

option

ThisT option(java.lang.String property,
             java.lang.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.

select

ThisT select(java.util.Collection<java.lang.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(java.lang.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(java.util.concurrent.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.