org.apache.hadoop.hbase.filter
Class SingleColumnValueFilter

java.lang.Object
  extended by org.apache.hadoop.hbase.filter.SingleColumnValueFilter
All Implemented Interfaces:
Filter, org.apache.hadoop.io.Writable

public class SingleColumnValueFilter
extends Object
implements Filter

This filter is used to filter cells based on value. It takes a CompareFilter.CompareOp operator (equal, greater, not equal, etc), and either a byte [] value or a WritableByteArrayComparable.

If we have a byte [] value then we just do a lexicographic compare. For example, if passed value is 'b' and cell has 'a' and the compare operator is LESS, then we will filter out this cell (return true). If this is not sufficient (eg you want to deserialize a long and then compare it to a fixed long value), then you can pass in your own comparator instead.

You must also specify a family and qualifier. Only the value of this column will be tested. All other

To prevent the entire row from being emitted if this filter determines the column does not pass (it should be filtered), wrap this filter with a SkipFilter.

To filter based on the value of all scanned columns, use ValueFilter.


Nested Class Summary
 
Nested classes/interfaces inherited from interface org.apache.hadoop.hbase.filter.Filter
Filter.ReturnCode
 
Constructor Summary
SingleColumnValueFilter()
          Writable constructor, do not use.
SingleColumnValueFilter(byte[] family, byte[] qualifier, CompareFilter.CompareOp compareOp, byte[] value)
          Constructor for binary compare of the value of a single column.
SingleColumnValueFilter(byte[] family, byte[] qualifier, CompareFilter.CompareOp compareOp, WritableByteArrayComparable comparator)
          Constructor for binary compare of the value of a single column.
 
Method Summary
 boolean filterAllRemaining()
          If this returns true, the scan will terminate.
 Filter.ReturnCode filterKeyValue(KeyValue keyValue)
          A way to filter based on the column family, column qualifier and/or the column value.
 boolean filterRow()
          Last chance to veto row based on previous Filter.filterKeyValue(KeyValue) calls.
 boolean filterRowKey(byte[] rowKey, int offset, int length)
          Filters a row based on the row key.
 void readFields(DataInput in)
           
 void reset()
          Reset the state of the filter between rows.
 void write(DataOutput out)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

SingleColumnValueFilter

public SingleColumnValueFilter()
Writable constructor, do not use.


SingleColumnValueFilter

public SingleColumnValueFilter(byte[] family,
                               byte[] qualifier,
                               CompareFilter.CompareOp compareOp,
                               byte[] value)
Constructor for binary compare of the value of a single column. If the column is found and the condition passes, all columns of the row will be emitted. If the column is not found or the condition fails, the row will not be emitted.

Parameters:
family - name of column family
qualifier - name of column qualifier
compareOp - operator
value - value to compare column values against

SingleColumnValueFilter

public SingleColumnValueFilter(byte[] family,
                               byte[] qualifier,
                               CompareFilter.CompareOp compareOp,
                               WritableByteArrayComparable comparator)
Constructor for binary compare of the value of a single column. If the column is found and the condition passes, all columns of the row will be emitted. If the condition fails, the row will not be emitted.

Use the filterIfColumnMissing flag to set whether the rest of the columns in a row will be emitted if the specified column to check is not found in the row.

Parameters:
family - name of column family
qualifier - name of column qualifier
compareOp - operator
comparator - Comparator to use.
Method Detail

filterRowKey

public boolean filterRowKey(byte[] rowKey,
                            int offset,
                            int length)
Description copied from interface: Filter
Filters a row based on the row key. If this returns true, the entire row will be excluded. If false, each KeyValue in the row will be passed to Filter.filterKeyValue(KeyValue) below.

Specified by:
filterRowKey in interface Filter
Parameters:
rowKey - buffer containing row key
offset - offset into buffer where row key starts
length - length of the row key
Returns:
true, remove entire row, false, include the row (maybe).

filterKeyValue

public Filter.ReturnCode filterKeyValue(KeyValue keyValue)
Description copied from interface: Filter
A way to filter based on the column family, column qualifier and/or the column value. Return code is described below. This allows filters to filter only certain number of columns, then terminate without matching ever column. If your filter returns ReturnCode.NEXT_ROW, it should return ReturnCode.NEXT_ROW until Filter.reset() is called just in case the caller calls for the next row.

Specified by:
filterKeyValue in interface Filter
Parameters:
keyValue - the KeyValue in question
Returns:
code as described below
See Also:
Filter.ReturnCode

filterAllRemaining

public boolean filterAllRemaining()
Description copied from interface: Filter
If this returns true, the scan will terminate.

Specified by:
filterAllRemaining in interface Filter
Returns:
true to end scan, false to continue.

filterRow

public boolean filterRow()
Description copied from interface: Filter
Last chance to veto row based on previous Filter.filterKeyValue(KeyValue) calls. The filter needs to retain state then return a particular value for this call if they wish to exclude a row if a certain column is missing (for example).

Specified by:
filterRow in interface Filter
Returns:
true to exclude row, false to include row.

reset

public void reset()
Description copied from interface: Filter
Reset the state of the filter between rows.

Specified by:
reset in interface Filter

readFields

public void readFields(DataInput in)
                throws IOException
Specified by:
readFields in interface org.apache.hadoop.io.Writable
Throws:
IOException

write

public void write(DataOutput out)
           throws IOException
Specified by:
write in interface org.apache.hadoop.io.Writable
Throws:
IOException


Copyright © 2009 The Apache Software Foundation