org.apache.hadoop.hive.ql.io.orc.Writer Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hive.ql.io.orc;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.List;
/**
* The interface for writing ORC files.
*/
public interface Writer {
/**
* Add arbitrary meta-data to the ORC file. This may be called at any point
* until the Writer is closed. If the same key is passed a second time, the
* second value will replace the first.
* @param key a key to label the data with.
* @param value the contents of the metadata.
*/
void addUserMetadata(String key, ByteBuffer value);
/**
* Add a row to the ORC file.
* @param row the row to add
* @throws IOException
*/
void addRow(Object row) throws IOException;
/**
* Flush all of the buffers and close the file. No methods on this writer
* should be called afterwards.
* @throws IOException
*/
void close() throws IOException;
/**
* Return the deserialized data size. Raw data size will be compute when
* writing the file footer. Hence raw data size value will be available only
* after closing the writer.
*
* @return raw data size
*/
long getRawDataSize();
/**
* Return the number of rows in file. Row count gets updated when flushing
* the stripes. To get accurate row count this method should be called after
* closing the writer.
*
* @return row count
*/
long getNumberOfRows();
/**
* Write an intermediate footer on the file such that if the file is
* truncated to the returned offset, it would be a valid ORC file.
* @return the offset that would be a valid end location for an ORC file
*/
long writeIntermediateFooter() throws IOException;
/**
* Fast stripe append to ORC file. This interface is used for fast ORC file
* merge with other ORC files. When merging, the file to be merged should pass
* stripe in binary form along with stripe information and stripe statistics.
* After appending last stripe of a file, use appendUserMetadata() to append
* any user metadata.
* @param stripe - stripe as byte array
* @param offset - offset within byte array
* @param length - length of stripe within byte array
* @param stripeInfo - stripe information
* @param stripeStatistics - stripe statistics (Protobuf objects can be
* merged directly)
* @throws IOException
*/
public void appendStripe(byte[] stripe, int offset, int length,
StripeInformation stripeInfo,
OrcProto.StripeStatistics stripeStatistics) throws IOException;
/**
* When fast stripe append is used for merging ORC stripes, after appending
* the last stripe from a file, this interface must be used to merge any
* user metadata.
* @param userMetadata - user metadata
*/
public void appendUserMetadata(List userMetadata);
}