org.apache.drill.exec.vector.accessor.reader

Class VectorAccessors

java.lang.Object

org.apache.drill.exec.vector.accessor.reader.VectorAccessors

public class VectorAccessors
extends Object

Collection of vector accessors. A single class handles the single-batch case. But, for hyper-vectors, we need a separate accessor for each (vector, sub-vector) combination to handle the indirections in the hyper-vector case.

For a required vector:
reader index --> hyper vector --> required vector

For a nullable vector:
reader index --> hyper vector --> nullable vector
nullable vector --> bits vector
--> values vector

For a repeated vector:
reader index --> hyper vector --> repeated vector
repeated vector --> offset vector
--> values vector

And so on. In each case, we must start with a top-level vector as indicated the row index, indirected through the SV4. That is done by the reader index. That points to a top-level vector in the hyper-vector.

Most of the vectors needed are nested. These inner vectors are not part of a hyper-vector list. Instead, we must get the top-level vector, then navigate down from that vector to the desired vector.

Sometimes the navigation is static (the "bits" vector for a nullable vector.) Other times, it is a bit more dynamic: a member of a map (given by index) or the member of a union (given by type.)

These accessors can be chained to handle deeply-nested structures such as an array of maps that contains a list of unions.

Because the navigation is required on every access, the use of hyper vectors is slow. Since hyper-vectors are seldom used, we optimize for the single-batch case by caching vectors at each stage. Thus, for the single-batch case, we use different accessor implementations. To keep the rest of the code simple, both the hyper and single batch cases use the same API, but they use entirely different implementations. The methods here choose the correct implementation for the single and hyper cases.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	VectorAccessors.ArrayDataHyperVectorAccessor Vector accessor for RepeatedVector → data vector
static class	VectorAccessors.ArrayOffsetHyperVectorAccessor Vector accessor for RepeatedVector → offsets vector
static class	VectorAccessors.BaseHyperVectorAccessor Vector accessor used by the column accessors to obtain the vector for each column value.
static class	VectorAccessors.ListBitsHyperVectorStateReader Vector accessor for ListVector → bits vector
static class	VectorAccessors.ListMemberHyperVectorAccessor
static class	VectorAccessors.MapMemberHyperVectorAccessor Vector accessor for AbstractMapVector → member vector
static class	VectorAccessors.NullableBitsHyperVectorStateReader Vector accessor for NullableVector → bits vector
static class	VectorAccessors.NullableValuesHyperVectorAccessor Vector accessor for NullableVector → values vector
static class	VectorAccessors.NullVectorAccesor
static class	VectorAccessors.SingleVectorAccessor
static class	VectorAccessors.UnionMemberHyperVectorAccessor Vector accessor for UnionVector → data vector
static class	VectorAccessors.UnionTypeHyperVectorAccessor Vector accessor for UnionVector → type vector
static class	VectorAccessors.VarWidthOffsetHyperVectorAccessor Vector accessor for VariableWidthVector → offsets vector

Constructor Summary

Constructors

Constructor and Description
VectorAccessors()

Method Summary

Modifier and Type	Method and Description
static VectorAccessor	arrayDataAccessor(VectorAccessor repeatedAccessor)
static VectorAccessor	arrayOffsetVectorAccessor(VectorAccessor repeatedAccessor)
static VectorAccessor	listBitsAccessor(VectorAccessor nullableAccessor)
static VectorAccessor	nullableBitsAccessor(VectorAccessor nullableAccessor)
static VectorAccessor	nullableValuesAccessor(VectorAccessor nullableAccessor)
static VectorAccessor	varWidthOffsetVectorAccessor(VectorAccessor varWidthAccessor)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

VectorAccessors

public VectorAccessors()

Method Detail

arrayOffsetVectorAccessor

public static VectorAccessor arrayOffsetVectorAccessor(VectorAccessor repeatedAccessor)

arrayDataAccessor

public static VectorAccessor arrayDataAccessor(VectorAccessor repeatedAccessor)

varWidthOffsetVectorAccessor

public static VectorAccessor varWidthOffsetVectorAccessor(VectorAccessor varWidthAccessor)

nullableValuesAccessor

public static VectorAccessor nullableValuesAccessor(VectorAccessor nullableAccessor)

nullableBitsAccessor

public static VectorAccessor nullableBitsAccessor(VectorAccessor nullableAccessor)

listBitsAccessor

public static VectorAccessor listBitsAccessor(VectorAccessor nullableAccessor)