org.apache.druid.segment.join.table

Interface IndexedTable

All Superinterfaces:

AutoCloseable, Closeable, ReferenceCountedObject

All Known Implementing Classes:

BroadcastSegmentIndexedTable, ReferenceCountingIndexedTable, RowBasedIndexedTable

public interface IndexedTable
extends ReferenceCountedObject, Closeable

An interface to a table where some columns (the 'key columns') have indexes that enable fast lookups. The main user of this class is IndexedTableJoinable, and its main purpose is to participate in joins.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	IndexedTable.Index Indexes support fast lookups on key columns.
static interface	IndexedTable.Reader Readers support reading values out of any column.

Method Summary

Modifier and Type	Method and Description
IndexedTable.Index	columnIndex(int column) Returns the index for a particular column.
IndexedTable.Reader	columnReader(int column) Returns a reader for a particular column.
default byte[]	computeCacheKey() Computes a byte[] key for the table that can be used for computing cache keys for join operations.
default boolean	isCacheable() Returns whether this indexed table can be cached for the join operations
Set<String>	keyColumns() Returns the columns of this table that have indexes.
default ColumnSelectorFactory	makeColumnSelectorFactory(ReadableOffset offset, boolean descending, Closer closer) This method allows a table to directly provide an optimized ColumnSelectorFactory for IndexedTableJoinMatcher to create selectors.
int	numRows() Returns the number of rows in this table.
RowSignature	rowSignature() Returns the signature of this table, which includes all key columns (as well as other columns that can be selected, but are not keys).
String	version() Returns the version of this table, used to compare against when loading a new version of the table

Methods inherited from interface org.apache.druid.segment.ReferenceCountedObject

acquireReferences

Methods inherited from interface java.io.Closeable

close

Method Detail

version

String version()

Returns the version of this table, used to compare against when loading a new version of the table

keyColumns

Set<String> keyColumns()

Returns the columns of this table that have indexes.

rowSignature

RowSignature rowSignature()

Returns the signature of this table, which includes all key columns (as well as other columns that can be selected, but are not keys).

numRows

int numRows()

Returns the number of rows in this table. It must not change over time, since it is used for things like algorithm selection and reporting of cardinality metadata.

columnIndex

IndexedTable.Index columnIndex(int column)

Returns the index for a particular column. The provided column number must be that column's position in rowSignature().

columnReader

IndexedTable.Reader columnReader(int column)

Returns a reader for a particular column. The provided column number must be that column's position in rowSignature(). Don't forget to close your IndexedTable.Reader when finished reading, to clean up any resources.

makeColumnSelectorFactory

@Nullable
default ColumnSelectorFactory makeColumnSelectorFactory(ReadableOffset offset,
                                                                  boolean descending,
                                                                  Closer closer)

This method allows a table to directly provide an optimized ColumnSelectorFactory for IndexedTableJoinMatcher to create selectors. If this method returns null, the default IndexedTableColumnSelectorFactory, which creates IndexedTableDimensionSelector or IndexedTableColumnValueSelector as appropriate, both backed with a columnReader(int), will be used instead.

computeCacheKey

default byte[] computeCacheKey()

Computes a byte[] key for the table that can be used for computing cache keys for join operations. see JoinableFactory.computeJoinCacheKey(org.apache.druid.query.DataSource, org.apache.druid.segment.join.JoinConditionAnalysis)

Returns:

the byte array for cache key

Throws:

{@link - IAE} if caching is not supported

isCacheable

default boolean isCacheable()

Returns whether this indexed table can be cached for the join operations