Reference (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.io.Reference

```
@InterfaceAudience.Private
public class Reference
extends Object
```
A reference to the top or bottom half of a store file where 'bottom' is the first half of the file containing the keys that sort lowest and 'top' is the second half of the file with keys that sort greater than those of the bottom half. The file referenced lives under a different region. References are made at region split time.
References work with a special half store file type. References know how to write out the reference format in the file system and are what is juggled when references are mixed in with direct store files. The half store file type is used reading the referred to file.
References to store files located over in some other region look like this in the file system 1278437856009925445.3323223323: i.e. an id followed by hash of the referenced region. Note, a region is itself not splittable if it has instances of store file references. References are cleaned up by compactions.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`(package private) static class`	`Reference.Range` For split HStoreFiles, it specifies if the file covers the lower half or the upper half of the key range

Field Summary

Fields
Modifier and Type Field and Description

private Reference.Range region

private byte[] splitkey

Fields
Modifier and Type	Field and Description
`private Reference.Range`	`region`
`private byte[]`	`splitkey`

Constructor Summary

Constructors
Constructor and Description

Reference()
Deprecated.
need by pb serialization

Reference(byte[] splitRow, Reference.Range fr)
Constructor

Constructors
Constructor and Description
`Reference()` Deprecated. need by pb serialization
`Reference(byte[] splitRow, Reference.Range fr)` Constructor

Method Summary

Methods
Modifier and Type	Method and Description
`org.apache.hadoop.hbase.protobuf.generated.FSProtos.Reference`	`convert()`
`static Reference`	`convert(org.apache.hadoop.hbase.protobuf.generated.FSProtos.Reference r)`
`static Reference`	`createBottomReference(byte[] splitRow)`
`static Reference`	`createTopReference(byte[] splitRow)`
`boolean`	`equals(Object o)`
`Reference.Range`	`getFileRegion()`
`byte[]`	`getSplitKey()`
`int`	`hashCode()`
`static boolean`	`isTopFileRegion(Reference.Range r)`
`static Reference`	`read(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path p)` Read a Reference from FileSystem.
`void`	`readFields(DataInput in)` Deprecated. Writables are going away. Use the pb serialization methods instead. Remove in a release after 0.96 goes out. This is here only to migrate old Reference files written with Writables before 0.96.
`(package private) byte[]`	`toByteArray()` Use this when writing to a stream and you want to use the pb mergeDelimitedFrom (w/o the delimiter, pb reads to EOF which may not be what you want).
`String`	`toString()`
`org.apache.hadoop.fs.Path`	`write(org.apache.hadoop.fs.FileSystem fs, org.apache.hadoop.fs.Path p)`

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

- Field Detail
  - splitkey
```
private byte[] splitkey
```
  - region
```
private Reference.Range region
```
- Constructor Detail
  - Reference
```
Reference(byte[] splitRow,
         Reference.Range fr)
```
    Constructor
    
    Parameters:
    splitRow - This is row we are splitting around.
    fr -
  - Reference
```
@Deprecated
public Reference()
```
    Deprecated. need by pb serialization
    
    Used by serializations.
- Method Detail
  - createTopReference
```
public static Reference createTopReference(byte[] splitRow)
```
    Parameters:
    splitRow -
    
    Returns:
    A Reference that points at top half of a an hfile
  - createBottomReference
```
public static Reference createBottomReference(byte[] splitRow)
```
    Parameters:
    splitRow -
    
    Returns:
    A Reference that points at the bottom half of a an hfile
  - getFileRegion
```
public Reference.Range getFileRegion()
```
    Returns:
    Range
  - getSplitKey
```
public byte[] getSplitKey()
```
    Returns:
    splitKey
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
    
    See Also:
    Object.toString()
  - isTopFileRegion
```
public static boolean isTopFileRegion(Reference.Range r)
```
  - readFields
```
@Deprecated
public void readFields(DataInput in)
                throws IOException
```
    Deprecated. Writables are going away. Use the pb serialization methods instead. Remove in a release after 0.96 goes out. This is here only to migrate old Reference files written with Writables before 0.96.
    
    Throws:
    
    IOException
  - write
```
public org.apache.hadoop.fs.Path write(org.apache.hadoop.fs.FileSystem fs,
                              org.apache.hadoop.fs.Path p)
                                throws IOException
```
    Throws:
    
    IOException
  - read
```
public static Reference read(org.apache.hadoop.fs.FileSystem fs,
             org.apache.hadoop.fs.Path p)
                      throws IOException
```
    Read a Reference from FileSystem.
    
    Parameters:
    fs -
    p -
    
    Returns:
    New Reference made from passed p
    
    Throws:
    
    IOException
  - convert
```
public org.apache.hadoop.hbase.protobuf.generated.FSProtos.Reference convert()
```
  - convert
```
public static Reference convert(org.apache.hadoop.hbase.protobuf.generated.FSProtos.Reference r)
```
  - toByteArray
```
byte[] toByteArray()
             throws IOException
```
    Use this when writing to a stream and you want to use the pb mergeDelimitedFrom (w/o the delimiter, pb reads to EOF which may not be what you want).
    
    Returns:
    This instance serialized as a delimited protobuf w/ a magic pb prefix.
    
    Throws:
    
    IOException
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - equals
```
public boolean equals(Object o)
```
    Overrides:
    
    equals in class Object

Class Reference

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

splitkey

region

Constructor Detail

Reference

Reference

Method Detail

createTopReference

createBottomReference

getFileRegion

getSplitKey

toString

isTopFileRegion

readFields

write

read

convert

convert

toByteArray

hashCode

equals