DataFileWriter (Apache Avro Java 1.10.2 API)

java.lang.Object
- org.apache.avro.file.DataFileWriter<D>

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable
```
public class DataFileWriter<D>
extends Object
implements Closeable, Flushable
```
Stores in a file a sequence of data conforming to a schema. The schema is stored in the file with the data. Each datum in a file is of the same schema. Data is written with a DatumWriter. Data is grouped into blocks. A synchronization marker is written between blocks, so that files may be split. Blocks may be compressed. Extensible metadata is stored at the end of the file. Files may be appended to.

See Also:

DataFileReader

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`DataFileWriter.AppendWriteException` Thrown by `append(Object)` when an exception occurs while writing a datum to the buffer.

Constructor Summary

Constructors
Constructor and Description

DataFileWriter(DatumWriter<D> dout)
Construct a writer, not yet open.

Constructors
Constructor and Description
`DataFileWriter(DatumWriter<D> dout)` Construct a writer, not yet open.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`append(D datum)` Append a datum to the file.
`void`	`appendAllFrom(DataFileStream<D> otherFile, boolean recompress)` Appends data from another file.
`void`	`appendEncoded(ByteBuffer datum)` Expert: Append a pre-encoded datum to the file.
`DataFileWriter<D>`	`appendTo(File file)` Open a writer appending to an existing file.
`DataFileWriter<D>`	`appendTo(SeekableInput in, OutputStream out)` Open a writer appending to an existing file.
`void`	`close()` Flush and close the file.
`DataFileWriter<D>`	`create(Schema schema, File file)` Open a new file for data matching a schema with a random sync.
`DataFileWriter<D>`	`create(Schema schema, OutputStream outs)` Open a new file for data matching a schema with a random sync.
`DataFileWriter<D>`	`create(Schema schema, OutputStream outs, byte[] sync)` Open a new file for data matching a schema with an explicit sync.
`void`	`flush()` Calls sync() and then flushes the current state of the file.
`void`	`fSync()` If this writer was instantiated using a File or using an Syncable instance, this method flushes all buffers for this writer to disk.
`boolean`	`isFlushOnEveryBlock()`
`static boolean`	`isReservedMeta(String key)`
`DataFileWriter<D>`	`setCodec(CodecFactory c)` Configures this writer to use the given codec.
`void`	`setFlushOnEveryBlock(boolean flushOnEveryBlock)` Set whether this writer should flush the block to the stream every time a sync marker is written.
`DataFileWriter<D>`	`setMeta(String key, byte[] value)` Set a metadata property.
`DataFileWriter<D>`	`setMeta(String key, long value)` Set a metadata property.
`DataFileWriter<D>`	`setMeta(String key, String value)` Set a metadata property.
`DataFileWriter<D>`	`setSyncInterval(int syncInterval)` Set the synchronization interval for this file, in bytes.
`long`	`sync()` Return the current position as a value that may be passed to `DataFileReader.seek(long)`.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - DataFileWriter
```
public DataFileWriter(DatumWriter<D> dout)
```
    Construct a writer, not yet open.
- Method Detail
  - setCodec
```
public DataFileWriter<D> setCodec(CodecFactory c)
```
    Configures this writer to use the given codec. May not be reset after writes have begun.
  - setSyncInterval
```
public DataFileWriter<D> setSyncInterval(int syncInterval)
```
    Set the synchronization interval for this file, in bytes. Valid values range from 32 to 2^30 Suggested values are between 2K and 2M The stream is flushed by default at the end of each synchronization interval. If setFlushOnEveryBlock(boolean) is called with param set to false, then the block may not be flushed to the stream after the sync marker is written. In this case, the flush() must be called to flush the stream. Invalid values throw IllegalArgumentException
    
    Parameters:
    
    syncInterval - the approximate number of uncompressed bytes to write in each block
    
    Returns:
    
    this DataFileWriter
  - create
```
public DataFileWriter<D> create(Schema schema,
                                File file)
                         throws IOException
```
    Open a new file for data matching a schema with a random sync.
    
    Throws:
    
    IOException
  - create
```
public DataFileWriter<D> create(Schema schema,
                                OutputStream outs)
                         throws IOException
```
    Open a new file for data matching a schema with a random sync.
    
    Throws:
    
    IOException
  - create
```
public DataFileWriter<D> create(Schema schema,
                                OutputStream outs,
                                byte[] sync)
                         throws IOException
```
    Open a new file for data matching a schema with an explicit sync.
    
    Throws:
    
    IOException
  - setFlushOnEveryBlock
```
public void setFlushOnEveryBlock(boolean flushOnEveryBlock)
```
    Set whether this writer should flush the block to the stream every time a sync marker is written. By default, the writer will flush the buffer each time a sync marker is written (if the block size limit is reached or the sync() is called.
    
    Parameters:
    
    flushOnEveryBlock - - If set to false, this writer will not flush the block to the stream until flush() is explicitly called.
  - isFlushOnEveryBlock
```
public boolean isFlushOnEveryBlock()
```
    Returns:
    
    - true if this writer flushes the block to the stream every time a sync marker is written. Else returns false.
  - appendTo
```
public DataFileWriter<D> appendTo(File file)
                           throws IOException
```
    Open a writer appending to an existing file.
    
    Throws:
    
    IOException
  - appendTo
```
public DataFileWriter<D> appendTo(SeekableInput in,
                                  OutputStream out)
                           throws IOException
```
    Open a writer appending to an existing file. Since 1.9.0 this method does not close in.
    
    Parameters:
    
    in - reading the existing file.
    
    out - positioned at the end of the existing file.
    
    Throws:
    
    IOException
  - setMeta
```
public DataFileWriter<D> setMeta(String key,
                                 byte[] value)
```
    Set a metadata property.
  - isReservedMeta
```
public static boolean isReservedMeta(String key)
```
  - setMeta
```
public DataFileWriter<D> setMeta(String key,
                                 String value)
```
    Set a metadata property.
  - setMeta
```
public DataFileWriter<D> setMeta(String key,
                                 long value)
```
    Set a metadata property.
  - append
```
public void append(D datum)
            throws IOException
```
    Append a datum to the file.
    
    Throws:
    
    IOException
    
    See Also:
    
    DataFileWriter.AppendWriteException
  - appendEncoded
```
public void appendEncoded(ByteBuffer datum)
                   throws IOException
```
    Expert: Append a pre-encoded datum to the file. No validation is performed to check that the encoding conforms to the file's schema. Appending non-conforming data may result in an unreadable file.
    
    Throws:
    
    IOException
  - appendAllFrom
```
public void appendAllFrom(DataFileStream<D> otherFile,
                          boolean recompress)
                   throws IOException
```
    Appends data from another file. otherFile must have the same schema. Data blocks will be copied without de-serializing data. If the codecs of the two files are compatible, data blocks are copied directly without decompression. If the codecs are not compatible, blocks from otherFile are uncompressed and then compressed using this file's codec.
    If the recompress flag is set all blocks are decompressed and then compressed using this file's codec. This is useful when the two files have compatible compression codecs but different codec options. For example, one might append a file compressed with deflate at compression level 1 to a file with deflate at compression level 7. If recompress is false, blocks will be copied without changing the compression level. If true, they will be converted to the new compression level.
    
    Parameters:
    
    otherFile -
    
    recompress -
    
    Throws:
    
    IOException
  - sync
```
public long sync()
          throws IOException
```
    Return the current position as a value that may be passed to DataFileReader.seek(long). Forces the end of the current block, emitting a synchronization marker. By default, this will also flush the block to the stream. If setFlushOnEveryBlock(boolean) is called with param set to false, then this method may not flush the block. In this case, the flush() must be called to flush the stream.
    
    Throws:
    
    IOException
  - flush
```
public void flush()
           throws IOException
```
    Calls sync() and then flushes the current state of the file.
    
    Specified by:
    
    flush in interface Flushable
    
    Throws:
    
    IOException
  - fSync
```
public void fSync()
           throws IOException
```
    If this writer was instantiated using a File or using an Syncable instance, this method flushes all buffers for this writer to disk. In other cases, this method behaves exactly like flush().
    
    Throws:
    
    IOException
  - close
```
public void close()
           throws IOException
```
    Flush and close the file.
    
    Specified by:
    
    close in interface Closeable
    
    Specified by:
    
    close in interface AutoCloseable
    
    Throws:
    
    IOException

Class DataFileWriter<D>

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

DataFileWriter

Method Detail

setCodec

setSyncInterval

create

create

create

setFlushOnEveryBlock

isFlushOnEveryBlock

appendTo

appendTo

setMeta

isReservedMeta

setMeta

setMeta

append

appendEncoded

appendAllFrom

sync

flush

fSync

close