/**
* Update a {@link Dataset} for the given dataset or view URI.
*
* <p>You can add columns, remove columns, or change the data type of columns in your dataset,
* provided you don't attempt a change that is incompatible with written data. Avro defines rules
* for compatible schema evolution. See <a
* href="http://kitesdk.org/docs/current/Schema-Evolution.html">Schema Evolution</a>.
*
* <p>This method updates the dataset descriptor, so you can also add or change properties.
*
* <p>The recommended way to update a dataset descriptor is to build it based on an existing
* descriptor. Use {@link DatasetDescriptor.Builder(DatasetDescriptor)} to build a
* DatasetDescriptor based on an existing instance.
*
* <p>You cannot change a dataset format or partition strategy.
*
* <p>URIs must begin with {@code dataset:}. The remainder of the URI is implementation specific,
* depending on the dataset scheme.
*
* @param uri a {@code Dataset} URI
* @param type a Java class that represents an entity in the dataset
* @param <E> the type used for readers and writers created by this {@code Dataset}
* @param <D> the type of {@code Dataset} expected
* @return a {@code Dataset} for the given URI
* @throws NullPointerException if {@code uri}, {@code descriptor}, or {@code type} is {@code
* null}
* @throws IllegalArgumentException if {@code uri} is not a dataset URI
* @throws DatasetNotFoundException if there is no dataset for the given URI
* @throws UnsupportedOperationException if descriptor updates are not supported by the
* implementation
* @throws ConcurrentSchemaModificationException if the {@code Dataset} schema is updated
* concurrently
* @throws IncompatibleSchemaException if the schema is not compatible with previous schemas, or
* with existing datasets with shared storage (for example, in the same HBase table)
*/
@SuppressWarnings("unchecked")
public static <E, D extends Dataset<E>> D update(
URI uri, DatasetDescriptor descriptor, Class<E> type) {
Preconditions.checkArgument(
URIBuilder.DATASET_SCHEME.equals(uri.getScheme()), "Not a dataset or view URI: " + uri);
Preconditions.checkNotNull(
type,
"The entity type can't be null, use Object.class to have the type"
+ " determined by the schema.");
Pair<DatasetRepository, Map<String, String>> pair =
Registration.lookupDatasetUri(URI.create(uri.getRawSchemeSpecificPart()));
DatasetRepository repo = pair.first();
Map<String, String> uriOptions = pair.second();
return (D)
repo.update(
uriOptions.get(URIBuilder.NAMESPACE_OPTION),
uriOptions.get(URIBuilder.DATASET_NAME_OPTION),
descriptor,
type);
}
