org.apache.druid.segment

Interface CursorFactory

All Known Subinterfaces:

StorageAdapter

All Known Implementing Classes:

HashJoinSegmentStorageAdapter, IncrementalIndexStorageAdapter, QueryableIndexStorageAdapter, RowBasedStorageAdapter

public interface CursorFactory

Interface extended by StorageAdapter, which gives them the power to create cursors.

See Also:

StorageAdapter

Method Summary

Modifier and Type	Method and Description
default boolean	canVectorize(Filter filter, VirtualColumns virtualColumns, boolean descending) Returns true if the provided combination of parameters can be handled by "makeVectorCursor".
Sequence<Cursor>	makeCursors(Filter filter, org.joda.time.Interval interval, VirtualColumns virtualColumns, Granularity gran, boolean descending, QueryMetrics<?> queryMetrics) Creates a sequence of Cursors, one for each time-granular bucket (based on the provided Granularity).
default VectorCursor	makeVectorCursor(Filter filter, org.joda.time.Interval interval, VirtualColumns virtualColumns, boolean descending, int vectorSize, QueryMetrics<?> queryMetrics) Creates a VectorCursor.

Method Detail

canVectorize

default boolean canVectorize(@Nullable
                             Filter filter,
                             VirtualColumns virtualColumns,
                             boolean descending)

Returns true if the provided combination of parameters can be handled by "makeVectorCursor". Query engines should use this before running in vectorized mode, and be prepared to fall back to non-vectorized mode if this method returns false.

makeCursors

Sequence<Cursor> makeCursors(@Nullable
                             Filter filter,
                             org.joda.time.Interval interval,
                             VirtualColumns virtualColumns,
                             Granularity gran,
                             boolean descending,
                             @Nullable
                             QueryMetrics<?> queryMetrics)

Creates a sequence of Cursors, one for each time-granular bucket (based on the provided Granularity).

makeVectorCursor

@Nullable
default VectorCursor makeVectorCursor(@Nullable
                                                Filter filter,
                                                org.joda.time.Interval interval,
                                                VirtualColumns virtualColumns,
                                                boolean descending,
                                                int vectorSize,
                                                @Nullable
                                                QueryMetrics<?> queryMetrics)

Creates a VectorCursor. Unlike the Cursor returned by "makeCursor", there is just one of these. Hence, this method does not take a "granularity" parameter. Before calling this method, check "canVectorize" to see if the call you are about to make will throw an error or not. Returns null if there is no data to walk over (for example, if the "interval" does not overlap the data interval of this segment).