View (Kite Development Kit 1.1.0 API)

Type Parameters:
E - The type of entities stored in the Dataset underlying this View.

All Known Subinterfaces:

Dataset<E>, PartitionView<E>, RandomAccessDataset<E>, RefinableView<E>, Signalable<E>
```
@Immutable
public interface View<E>
```
A View is a subset of a Dataset. A View defines a space of potential storage keys or a partition space. Views can be created from ranges, partial keys, or the union of other views.

Since:

0.9.0

Method Summary

Methods
Modifier and Type	Method and Description
`View<GenericRecord>`	`asSchema(Schema schema)` Creates a copy of this `View` that projects entities to the given `Schema`.
`<T> View<T>`	`asType(Class<T> type)` Creates a copy of this `View` that reads and writes entities of the given type class.
`boolean`	`deleteAll()` Deletes the entities included in this `View` or throws an `UnsupportedOperationException`.
`Iterable<PartitionView<E>>`	`getCoveringPartitions()` Returns an `Iterable` of non-overlapping `View` objects that partition the underlying `Dataset` and cover this `View`.
`Dataset<E>`	`getDataset()` Returns the underlying `Dataset` for the `View`.
`Schema`	`getSchema()` Get the schema of entities contained in this `View`.
`Class<E>`	`getType()` Get the runtime type of entities contained in this `View`.
`URI`	`getUri()` Get a `URI` that identifies this `View`.
`boolean`	`includes(E entity)` Returns whether an entity `Object` would be included in this `View` if it were present in the `Dataset`.
`boolean`	`isEmpty()` Check whether this `View` contains any records.
`DatasetReader<E>`	`newReader()` Get an appropriate `DatasetReader` implementation based on this `View` of the underlying `Dataset` implementation.
`DatasetWriter<E>`	`newWriter()` Get an appropriate `DatasetWriter` implementation based on this `View` of the underlying `Dataset` implementation.

- Method Detail
  - getDataset
```
Dataset<E> getDataset()
```
    Returns the underlying Dataset for the View.
    
    Returns:
    the underlying Dataset
  - newReader
```
DatasetReader<E> newReader()
```
    Get an appropriate DatasetReader implementation based on this View of the underlying Dataset implementation. Implementations are free to return different types of readers, depending on the disposition of the data. For example, a partitioned dataset can use a different reader than that of a non-partitioned dataset. Clients should not make any assumptions about the returned implementations: implementations are free to change their internal structure at any time.
    
    Throws:
    
    DatasetException
  - newWriter
```
DatasetWriter<E> newWriter()
```
    Get an appropriate DatasetWriter implementation based on this View of the underlying Dataset implementation. Implementations are free to return different types of writers depending on the disposition of the data. For example, a partitioned dataset may use a different writer than that of a non-partitioned dataset. Clients should not make any assumptions about the returned implementations: implementations are free to change their internal structure at any time.
    
    Throws:
    
    DatasetException
  - includes
```
boolean includes(E entity)
```
    Returns whether an entity Object would be included in this View if it were present in the Dataset.
    
    Parameters:
    entity - an entity Object
    
    Returns:
    true if entity is in the partition space of this view.
    Since:
    
    0.11.0
  - deleteAll
```
boolean deleteAll()
```
    Deletes the entities included in this View or throws an UnsupportedOperationException. Implementations are allowed to throw UnsupportedOperationException if the View could require additional work to delete. For example, if some but not all of the data in an underlying data file must be removed, then the implementation is allowed to reject the deletion rather than copy the remaining records to a new file. Implementations must document what deletes are supported and under what conditions deletes are rejected.
    
    Returns:
    true if any data was deleted, false if the View was already empty
    
    Throws:
    
    UnsupportedOperationException - if the requested delete cannot be completed by the implementation
    
    DatasetIOException - if the requested delete failed because of an IOException
    Since:
    
    0.12.0
  - getType
```
Class<E> getType()
```
    Get the runtime type of entities contained in this View.
    
    Returns:
    the runtime type of entities contained in this view
    Since:
    
    0.15.0
  - getSchema
```
Schema getSchema()
```
    Get the schema of entities contained in this View.
    
    Returns:
    the schema of entities contained in this view
    Since:
    
    1.1.0
  - isEmpty
```
boolean isEmpty()
```
    Check whether this View contains any records. Implementations should return once a single record in this view is found. But this might require scanning through large amounts of data sequentially to determine if there are any records.
    
    Returns:
    true if least one record exists, false otherwise
    Since:
    
    0.15.0
  - getUri
```
URI getUri()
```
    Get a URI that identifies this View.
    
    Returns:
    a URI for this view.
    Since:
    
    0.16.0
  - getCoveringPartitions
```
Iterable<PartitionView<E>> getCoveringPartitions()
```
    Returns an Iterable of non-overlapping View objects that partition the underlying Dataset and cover this View. The returned View objects are implementation-specific, but should represent reasonable partitions of the underlying Dataset based on its layout. The data contained by the union of each View in the Iterable must be a super-set of this View. Note that partitions are actual partitions under which data is stored. Implementations should omit any View that is empty.
    
    Returns:
    An Iterable of the View that cover this View.
    
    Throws:
    
    IllegalStateException - If the underlying Dataset is not partitioned.
    
    UnsupportedOperationException - If the implementation does not support covering partitions.
    Since:
    
    1.1.0
  - asSchema
```
View<GenericRecord> asSchema(Schema schema)
```
    Creates a copy of this View that projects entities to the given Schema.
    This method always returns a View with type GenericRecord.
    
    Parameters:
    schema - an Avro schema to project entities to
    
    Returns:
    a copy of this view that projects entities to the given schema
    
    Throws:
    
    IncompatibleSchemaException - If the given schema is incompatible with the underlying dataset.
    Since:
    
    1.1.0
  - asType
```
<T> View<T> asType(Class<T> type)
```
    Creates a copy of this View that reads and writes entities of the given type class.
    
    Type Parameters:
    T - the type of entities that will be read or written by this view
    Parameters:
    type - an entity class to use
    
    Returns:
    a copy of this view that projects entities to the given type
    
    Throws:
    
    IncompatibleSchemaException - If the given type is incompatible with the underlying dataset.
    Since:
    
    1.1.0

Interface View<E>

Method Summary

Method Detail

getDataset

newReader

newWriter

includes

deleteAll

getType

getSchema

isEmpty

getUri

getCoveringPartitions

asSchema

asType