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public interface HFileScanner
A scanner allows you to position yourself within a HFile and scan through it. It allows you to reposition yourself as well.
A scanner doesn't always have a key/value that it is pointing to
when it is first created and before
seekTo()
/seekTo(byte[])
are called.
In this case, getKey()
/getValue()
returns null. At most
other times, a key and value will be available. The general pattern is that
you position the Scanner using the seekTo variants and then getKey and
getValue.
Method Summary | |
---|---|
ByteBuffer |
getKey()
Gets a buffer view to the current key. |
String |
getKeyString()
Convenience method to get a copy of the key as a string - interpreting the bytes as UTF8. |
KeyValue |
getKeyValue()
|
HFile.Reader |
getReader()
|
ByteBuffer |
getValue()
Gets a buffer view to the current value. |
String |
getValueString()
Convenience method to get a copy of the value as a string - interpreting the bytes as UTF8. |
boolean |
isSeeked()
|
boolean |
next()
Scans to the next entry in the file. |
int |
reseekTo(byte[] key)
Reseek to or just before the passed key . |
int |
reseekTo(byte[] key,
int offset,
int length)
|
boolean |
seekBefore(byte[] key)
Consider the key stream of all the keys in the file, k[0] .. |
boolean |
seekBefore(byte[] key,
int offset,
int length)
|
boolean |
seekTo()
Positions this scanner at the start of the file. |
int |
seekTo(byte[] key)
SeekTo or just before the passed key . |
int |
seekTo(byte[] key,
int offset,
int length)
|
Method Detail |
---|
int seekTo(byte[] key) throws IOException
key
. Examine the return
code to figure whether we found the key or not.
Consider the key stream of all the keys in the file,
k[0] .. k[n]
, where there are n keys in the file.
key
- Key to find.
IOException
int seekTo(byte[] key, int offset, int length) throws IOException
IOException
int reseekTo(byte[] key) throws IOException
key
. Similar to seekTo
except that this can be called even if the scanner is not at the beginning
of a file.
This can be used to seek only to keys which come after the current position
of the scanner.
Consider the key stream of all the keys in the file,
k[0] .. k[n]
, where there are n keys in the file after
current position of HFileScanner.
The scanner will position itself between k[i] and k[i+1] where
k[i] < key <= k[i+1].
If there is no key k[i+1] greater than or equal to the input key, then the
scanner will position itself at the end of the file and next() will return
false when it is called.
key
- Key to find (should be non-null)
IOException
int reseekTo(byte[] key, int offset, int length) throws IOException
IOException
boolean seekBefore(byte[] key) throws IOException
k[0] .. k[n]
, where there are n keys in the file.
key
- Key to find
IOException
boolean seekBefore(byte[] key, int offset, int length) throws IOException
IOException
boolean seekTo() throws IOException
IOException
boolean next() throws IOException
IOException
ByteBuffer getKey()
seekTo(byte[])
before this method.
ByteBuffer getValue()
seekTo(byte[])
before this method.
KeyValue getKeyValue()
KeyValue
.String getKeyString()
seekTo(byte[])
before this method.
String getValueString()
seekTo(byte[])
before this method.
HFile.Reader getReader()
boolean isSeeked()
seekBefore(byte[])
or seekTo()
or seekTo(byte[])
.
Otherwise returns false.
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