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java.lang.Objectorg.apache.hadoop.io.file.tfile.TFile.Reader
public static class TFile.Reader
TFile Reader. Users may only read TFiles by creating TFile.Reader.Scanner.
objects. A scanner may scan the whole TFile (createScanner()
) , a portion of TFile based on byte offsets (
createScannerByByteRange(long, long)), or a portion of TFile with keys
fall in a certain key range (for sorted TFile only,
createScannerByKey(byte[], byte[]) or
createScannerByKey(RawComparable, RawComparable)).
| Nested Class Summary | |
|---|---|
static class |
TFile.Reader.Scanner
The TFile Scanner. |
| Constructor Summary | |
|---|---|
TFile.Reader(FSDataInputStream fsdis,
long fileLength,
Configuration conf)
Constructor |
|
| Method Summary | |
|---|---|
void |
close()
Close the reader. |
TFile.Reader.Scanner |
createScanner()
Get a scanner than can scan the whole TFile. |
TFile.Reader.Scanner |
createScanner(byte[] beginKey,
byte[] endKey)
Deprecated. Use createScannerByKey(byte[], byte[]) instead. |
TFile.Reader.Scanner |
createScanner(RawComparable beginKey,
RawComparable endKey)
Deprecated. Use createScannerByKey(RawComparable, RawComparable)
instead. |
TFile.Reader.Scanner |
createScannerByByteRange(long offset,
long length)
Get a scanner that covers a portion of TFile based on byte offsets. |
TFile.Reader.Scanner |
createScannerByKey(byte[] beginKey,
byte[] endKey)
Get a scanner that covers a portion of TFile based on keys. |
TFile.Reader.Scanner |
createScannerByKey(RawComparable beginKey,
RawComparable endKey)
Get a scanner that covers a specific key range. |
TFile.Reader.Scanner |
createScannerByRecordNum(long beginRecNum,
long endRecNum)
Create a scanner that covers a range of records. |
Comparator<RawComparable> |
getComparator()
Get an instance of the RawComparator that is constructed based on the string comparator representation. |
String |
getComparatorName()
Get the string representation of the comparator. |
Comparator<TFile.Reader.Scanner.Entry> |
getEntryComparator()
Get a Comparator object to compare Entries. |
long |
getEntryCount()
Get the number of key-value pair entries in TFile. |
RawComparable |
getFirstKey()
Get the first key in the TFile. |
RawComparable |
getKeyNear(long offset)
Get a sample key that is within a block whose starting offset is greater than or equal to the specified offset. |
RawComparable |
getLastKey()
Get the last key in the TFile. |
DataInputStream |
getMetaBlock(String name)
Stream access to a meta block.`` |
long |
getRecordNumNear(long offset)
Get the RecordNum for the first key-value pair in a compressed block whose byte offset in the TFile is greater than or equal to the specified offset. |
boolean |
isSorted()
Is the TFile sorted? |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
|---|
public TFile.Reader(FSDataInputStream fsdis,
long fileLength,
Configuration conf)
throws IOException
fsdis - FS input stream of the TFile.fileLength - The length of TFile. This is required because we have no easy
way of knowing the actual size of the input file through the
File input stream.conf -
IOException| Method Detail |
|---|
public void close()
throws IOException
close in interface CloseableIOExceptionpublic String getComparatorName()
public boolean isSorted()
public long getEntryCount()
public RawComparable getFirstKey()
throws IOException
IOException
public RawComparable getLastKey()
throws IOException
IOExceptionpublic Comparator<TFile.Reader.Scanner.Entry> getEntryComparator()
public Comparator<RawComparable> getComparator()
public DataInputStream getMetaBlock(String name)
throws IOException,
MetaBlockDoesNotExist
name - The name of the meta block.
IOException - on I/O error.
MetaBlockDoesNotExist - If the meta block with the name does not exist.
public long getRecordNumNear(long offset)
throws IOException
offset - the user supplied offset.
IOException
public RawComparable getKeyNear(long offset)
throws IOException
offset - The file offset.
IOException
public TFile.Reader.Scanner createScanner()
throws IOException
IOException
public TFile.Reader.Scanner createScannerByByteRange(long offset,
long length)
throws IOException
offset - The beginning byte offset in the TFile.length - The length of the region.
IOException
@Deprecated
public TFile.Reader.Scanner createScanner(byte[] beginKey,
byte[] endKey)
throws IOException
createScannerByKey(byte[], byte[]) instead.
beginKey - Begin key of the scan (inclusive). If null, scan from the first
key-value entry of the TFile.endKey - End key of the scan (exclusive). If null, scan up to the last
key-value entry of the TFile.
IOException
public TFile.Reader.Scanner createScannerByKey(byte[] beginKey,
byte[] endKey)
throws IOException
beginKey - Begin key of the scan (inclusive). If null, scan from the first
key-value entry of the TFile.endKey - End key of the scan (exclusive). If null, scan up to the last
key-value entry of the TFile.
IOException
@Deprecated
public TFile.Reader.Scanner createScanner(RawComparable beginKey,
RawComparable endKey)
throws IOException
createScannerByKey(RawComparable, RawComparable)
instead.
beginKey - Begin key of the scan (inclusive). If null, scan from the first
key-value entry of the TFile.endKey - End key of the scan (exclusive). If null, scan up to the last
key-value entry of the TFile.
IOException
public TFile.Reader.Scanner createScannerByKey(RawComparable beginKey,
RawComparable endKey)
throws IOException
beginKey - Begin key of the scan (inclusive). If null, scan from the first
key-value entry of the TFile.endKey - End key of the scan (exclusive). If null, scan up to the last
key-value entry of the TFile.
IOException
public TFile.Reader.Scanner createScannerByRecordNum(long beginRecNum,
long endRecNum)
throws IOException
beginRecNum - The RecordNum for the first record (inclusive).endRecNum - The RecordNum for the last record (exclusive). To scan the whole
file, either specify endRecNum==-1 or endRecNum==getEntryCount().
IOException
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