org.apache.hadoop.hbase.regionserver

类 NonLazyKeyValueScanner

java.lang.Object

org.apache.hadoop.hbase.regionserver.NonLazyKeyValueScanner

所有已实现的接口:

Closeable, AutoCloseable, KeyValueScanner, Shipper

直接已知子类:

NonReversedNonLazyKeyValueScanner

@InterfaceAudience.Private
public abstract class NonLazyKeyValueScanner
extends Object
implements KeyValueScanner

A "non-lazy" scanner which always does a real seek operation. Most scanners are inherited from this class.

字段概要

从接口继承的字段 org.apache.hadoop.hbase.regionserver.KeyValueScanner

NO_NEXT_INDEXED_KEY

构造器概要

构造器

构造器和说明
NonLazyKeyValueScanner()

方法概要

限定符和类型	方法和说明
static boolean	doRealSeek(KeyValueScanner scanner, Cell kv, boolean forward)
void	enforceSeek() Does the real seek operation in case it was skipped by seekToRowCol(KeyValue, boolean) (TODO: Whats this?).
org.apache.hadoop.fs.Path	getFilePath()
Cell	getNextIndexedKey()
boolean	isFileScanner()
boolean	realSeekDone() We optimize our store scanners by checking the most recent store file first, so we sometimes pretend we have done a seek but delay it until the store scanner bubbles up to the top of the key-value heap.
boolean	requestSeek(Cell kv, boolean forward, boolean useBloom) Similar to KeyValueScanner.seek(org.apache.hadoop.hbase.Cell) (or KeyValueScanner.reseek(org.apache.hadoop.hbase.Cell) if forward is true) but only does a seek operation after checking that it is really necessary for the row/column combination specified by the kv parameter.
void	shipped() Called after a batch of rows scanned and set to be returned to client.
boolean	shouldUseScanner(Scan scan, HStore store, long oldestUnexpiredTS) Allows to filter out scanners (both StoreFile and memstore) that we don't want to use based on criteria such as Bloom filters and timestamp ranges.

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

从接口继承的方法 org.apache.hadoop.hbase.regionserver.KeyValueScanner

backwardSeek, close, getScannerOrder, next, peek, reseek, seek, seekToLastRow, seekToPreviousRow

构造器详细资料

NonLazyKeyValueScanner

public NonLazyKeyValueScanner()

方法详细资料

requestSeek

public boolean requestSeek(Cell kv,
                           boolean forward,
                           boolean useBloom)
                    throws IOException

从接口复制的说明: KeyValueScanner

Similar to KeyValueScanner.seek(org.apache.hadoop.hbase.Cell) (or KeyValueScanner.reseek(org.apache.hadoop.hbase.Cell) if forward is true) but only does a seek operation after checking that it is really necessary for the row/column combination specified by the kv parameter. This function was added to avoid unnecessary disk seeks by checking row-column Bloom filters before a seek on multi-column get/scan queries, and to optimize by looking up more recent files first.

指定者:

requestSeek 在接口中 KeyValueScanner

forward - do a forward-only "reseek" instead of a random-access seek

useBloom - whether to enable multi-column Bloom filter optimization

抛出:

IOException

realSeekDone

public boolean realSeekDone()

从接口复制的说明: KeyValueScanner

We optimize our store scanners by checking the most recent store file first, so we sometimes pretend we have done a seek but delay it until the store scanner bubbles up to the top of the key-value heap. This method is then used to ensure the top store file scanner has done a seek operation.

指定者:

realSeekDone 在接口中 KeyValueScanner

enforceSeek

public void enforceSeek()
                 throws IOException

从接口复制的说明: KeyValueScanner

Does the real seek operation in case it was skipped by seekToRowCol(KeyValue, boolean) (TODO: Whats this?). Note that this function should be never called on scanners that always do real seek operations (i.e. most of the scanners). The easiest way to achieve this is to call KeyValueScanner.realSeekDone() first.

指定者:

enforceSeek 在接口中 KeyValueScanner

抛出:

IOException

doRealSeek

public static boolean doRealSeek(KeyValueScanner scanner,
                                 Cell kv,
                                 boolean forward)
                          throws IOException

抛出:

IOException

shouldUseScanner

public boolean shouldUseScanner(Scan scan,
                                HStore store,
                                long oldestUnexpiredTS)

从接口复制的说明: KeyValueScanner

Allows to filter out scanners (both StoreFile and memstore) that we don't want to use based on criteria such as Bloom filters and timestamp ranges.

指定者:

shouldUseScanner 在接口中 KeyValueScanner

参数:

scan - the scan that we are selecting scanners for

store - the store we are performing the scan on.

oldestUnexpiredTS - the oldest timestamp we are interested in for this query, based on TTL

返回:

true if the scanner should be included in the query

isFileScanner

public boolean isFileScanner()

指定者:

isFileScanner 在接口中 KeyValueScanner

返回:

true if this is a file scanner. Otherwise a memory scanner is assumed.

getFilePath

public org.apache.hadoop.fs.Path getFilePath()

指定者:

getFilePath 在接口中 KeyValueScanner

返回:

the file path if this is a file scanner, otherwise null.

另请参阅:

KeyValueScanner.isFileScanner()

getNextIndexedKey

public Cell getNextIndexedKey()

指定者:

getNextIndexedKey 在接口中 KeyValueScanner

返回:

the next key in the index, usually the first key of next block OR a key that falls between last key of current block and first key of next block.. see HFileWriterImpl#getMidpoint, or null if not known.

shipped

public void shipped()
             throws IOException

从接口复制的说明: Shipper

Called after a batch of rows scanned and set to be returned to client. Any in between cleanup can be done here.

指定者:

shipped 在接口中 Shipper

抛出:

IOException