ScanQueryMatcher (Apache HBase 1.4.11 API)

java.lang.Object
- org.apache.hadoop.hbase.regionserver.querymatcher.ScanQueryMatcher

Direct Known Subclasses:

CompactionScanQueryMatcher, LegacyScanQueryMatcher, UserScanQueryMatcher
```
@InterfaceAudience.Private
public abstract class ScanQueryMatcher
extends Object
```
A query matcher that is specifically designed for the scan case.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class ScanQueryMatcher.MatchCode
match(org.apache.hadoop.hbase.Cell) return codes.

Nested Classes
Modifier and Type	Class and Description
`static class`	`ScanQueryMatcher.MatchCode` `match(org.apache.hadoop.hbase.Cell)` return codes.

Field Summary

Fields
Modifier and Type	Field and Description
`protected ColumnTracker`	`columns` Keeps track of columns and versions
`protected Cell`	`currentRow` Row the query is on
`protected long`	`now`
`protected long`	`oldestUnexpiredTS` The oldest timestamp we are interested in, based on TTL
`protected KeyValue.KVComparator`	`rowComparator` Row comparator for the region this query is for
`protected Cell`	`startKey` Key to seek to in memstore and StoreFiles

Constructor Summary

Constructors
Modifier	Constructor and Description
`protected`	`ScanQueryMatcher(Cell startKey, ScanInfo scanInfo, ColumnTracker columns, long oldestUnexpiredTS, long now)`

Method Summary

Methods
Modifier and Type	Method and Description
`protected ScanQueryMatcher.MatchCode`	`checkDeleted(DeleteTracker deletes, Cell cell)`
`void`	`clearCurrentRow()` Make `currentRow()` return null.
`int`	`compareKeyForNextColumn(Cell nextIndexed, Cell currentCell)`
`int`	`compareKeyForNextRow(Cell nextIndexed, Cell currentCell)`
`protected static Cell`	`createStartKeyFromRow(byte[] startRow, ScanInfo scanInfo)`
`Cell`	`currentRow()`
`abstract Filter`	`getFilter()`
`Cell`	`getKeyForNextColumn(Cell cell)`
`abstract Cell`	`getNextKeyHint(Cell cell)` Delegate to `Filter.getNextCellHint(Cell)`.
`Cell`	`getStartKey()`
`abstract boolean`	`hasNullColumnInQuery()`
`protected static DeleteTracker`	`instantiateDeleteTracker(RegionCoprocessorHost host)`
`abstract boolean`	`isUserScan()`
`abstract ScanQueryMatcher.MatchCode`	`match(Cell cell)` Determines if the caller should do one of several things: seek/skip to the next row (MatchCode.SEEK_NEXT_ROW) seek/skip to the next column (MatchCode.SEEK_NEXT_COL) include the current KeyValue (MatchCode.INCLUDE) ignore the current KeyValue (MatchCode.SKIP) got to the next row (MatchCode.DONE)
`abstract boolean`	`moreRowsMayExistAfter(Cell cell)`
`protected ScanQueryMatcher.MatchCode`	`preCheck(Cell cell)` Check before the delete logic.
`protected abstract void`	`reset()`
`void`	`setToNewRow(Cell currentRow)` Set the row when there is change in row

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

- Field Detail
  - rowComparator
```
protected final KeyValue.KVComparator rowComparator
```
    Row comparator for the region this query is for
  - startKey
```
protected final Cell startKey
```
    Key to seek to in memstore and StoreFiles
  - columns
```
protected final ColumnTracker columns
```
    Keeps track of columns and versions
  - oldestUnexpiredTS
```
protected final long oldestUnexpiredTS
```
    The oldest timestamp we are interested in, based on TTL
  - now
```
protected final long now
```
  - currentRow
```
protected Cell currentRow
```
    Row the query is on
- Constructor Detail
  - ScanQueryMatcher
```
protected ScanQueryMatcher(Cell startKey,
                ScanInfo scanInfo,
                ColumnTracker columns,
                long oldestUnexpiredTS,
                long now)
```
- Method Detail
  - createStartKeyFromRow
```
protected static Cell createStartKeyFromRow(byte[] startRow,
                         ScanInfo scanInfo)
```
  - preCheck
```
protected final ScanQueryMatcher.MatchCode preCheck(Cell cell)
```
    Check before the delete logic.
    
    Returns:
    null means continue.
  - checkDeleted
```
protected final ScanQueryMatcher.MatchCode checkDeleted(DeleteTracker deletes,
                                      Cell cell)
```
  - match
```
public abstract ScanQueryMatcher.MatchCode match(Cell cell)
                                          throws IOException
```
    Determines if the caller should do one of several things:
    - seek/skip to the next row (MatchCode.SEEK_NEXT_ROW)
    - seek/skip to the next column (MatchCode.SEEK_NEXT_COL)
    - include the current KeyValue (MatchCode.INCLUDE)
    - ignore the current KeyValue (MatchCode.SKIP)
    - got to the next row (MatchCode.DONE)
    Parameters:
    cell - KeyValue to check
    
    Returns:
    The match code instance.
    
    Throws:
    
    IOException - in case there is an internal consistency problem caused by a data corruption.
  - getStartKey
```
public Cell getStartKey()
```
    Returns:
    the start key
  - hasNullColumnInQuery
```
public abstract boolean hasNullColumnInQuery()
```
    Returns:
    whether there is an null column in the query
  - currentRow
```
public Cell currentRow()
```
    Returns:
    a cell represent the current row
  - clearCurrentRow
```
public void clearCurrentRow()
```
    Make currentRow() return null.
  - reset
```
protected abstract void reset()
```
  - setToNewRow
```
public void setToNewRow(Cell currentRow)
```
    Set the row when there is change in row
    
    Parameters:
    currentRow -
  - isUserScan
```
public abstract boolean isUserScan()
```
  - moreRowsMayExistAfter
```
public abstract boolean moreRowsMayExistAfter(Cell cell)
```
    Returns:
    Returns false if we know there are no more rows to be scanned (We've reached the stopRow or we are scanning on row only because this Scan is for a Get, etc.
  - getKeyForNextColumn
```
public Cell getKeyForNextColumn(Cell cell)
```
  - compareKeyForNextRow
```
public int compareKeyForNextRow(Cell nextIndexed,
                       Cell currentCell)
```
    Parameters:
    nextIndexed - the key of the next entry in the block index (if any)
    currentCell - The Cell we're using to calculate the seek key
    
    Returns:
    result of the compare between the indexed key and the key portion of the passed cell
  - compareKeyForNextColumn
```
public int compareKeyForNextColumn(Cell nextIndexed,
                          Cell currentCell)
```
    Parameters:
    nextIndexed - the key of the next entry in the block index (if any)
    currentCell - The Cell we're using to calculate the seek key
    
    Returns:
    result of the compare between the indexed key and the key portion of the passed cell
  - getFilter
```
public abstract Filter getFilter()
```
    Returns:
    the Filter
  - getNextKeyHint
```
public abstract Cell getNextKeyHint(Cell cell)
                             throws IOException
```
    Delegate to Filter.getNextCellHint(Cell). If no filter, return null.
    
    Throws:
    
    IOException
  - instantiateDeleteTracker
```
protected static DeleteTracker instantiateDeleteTracker(RegionCoprocessorHost host)
                                                 throws IOException
```
    Throws:
    
    IOException

Class ScanQueryMatcher

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

rowComparator

startKey

columns

oldestUnexpiredTS

now

currentRow

Constructor Detail

ScanQueryMatcher

Method Detail

createStartKeyFromRow

preCheck

checkDeleted

match

getStartKey

hasNullColumnInQuery

currentRow

clearCurrentRow

reset

setToNewRow

isUserScan

moreRowsMayExistAfter

getKeyForNextColumn

compareKeyForNextRow

compareKeyForNextColumn

getFilter

getNextKeyHint

instantiateDeleteTracker