org.apache.hadoop.hbase.filter

Class MultiRowRangeFilter

java.lang.Object

org.apache.hadoop.hbase.filter.Filter

org.apache.hadoop.hbase.filter.FilterBase

org.apache.hadoop.hbase.filter.MultiRowRangeFilter

@InterfaceAudience.Public
@InterfaceStability.Evolving
public class MultiRowRangeFilter
extends FilterBase

Filter to support scan multiple row key ranges. It can construct the row key ranges from the passed list which can be accessed by each region server. HBase is quite efficient when scanning only one small row key range. If user needs to specify multiple row key ranges in one scan, the typical solutions are: 1. through FilterList which is a list of row key Filters, 2. using the SQL layer over HBase to join with two table, such as hive, phoenix etc. However, both solutions are inefficient. Both of them can't utilize the range info to perform fast forwarding during scan which is quite time consuming. If the number of ranges are quite big (e.g. millions), join is a proper solution though it is slow. However, there are cases that user wants to specify a small number of ranges to scan (e.g. <1000 ranges). Both solutions can't provide satisfactory performance in such case. MultiRowRangeFilter is to support such usec ase (scan multiple row key ranges), which can construct the row key ranges from user specified list and perform fast-forwarding during scan. Thus, the scan will be quite efficient.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MultiRowRangeFilter.RowRange

Nested classes/interfaces inherited from class org.apache.hadoop.hbase.filter.Filter

Filter.ReturnCode

Field Summary

Fields inherited from class org.apache.hadoop.hbase.filter.Filter

reversed

Constructor Summary

Constructors

Constructor and Description
MultiRowRangeFilter(List<MultiRowRangeFilter.RowRange> list)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	filterAllRemaining() Filters that never filter all remaining can inherit this implementation that never stops the filter early.
Filter.ReturnCode	filterKeyValue(Cell ignored) A way to filter based on the column family, column qualifier and/or the column value.
boolean	filterRowKey(byte[] buffer, int offset, int length) Filters that do not filter by row key can inherit this implementation that never filters anything.
Cell	getNextCellHint(Cell currentKV) Filters that are not sure which key must be next seeked to, can inherit this implementation that, by default, returns a null Cell.
List<MultiRowRangeFilter.RowRange>	getRowRanges()
static MultiRowRangeFilter	parseFrom(byte[] pbBytes)
static List<MultiRowRangeFilter.RowRange>	sortAndMerge(List<MultiRowRangeFilter.RowRange> ranges) sort the ranges and if the ranges with overlap, then merge them.
byte[]	toByteArray() Return length 0 byte array for Filters that don't require special serialization

Methods inherited from class org.apache.hadoop.hbase.filter.FilterBase

createFilterFromArguments, filterRow, filterRowCells, getNextKeyHint, hasFilterRow, isFamilyEssential, reset, toString, transform, transformCell

Methods inherited from class org.apache.hadoop.hbase.filter.Filter

isReversed, setReversed

Methods inherited from class java.lang.Object

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

Constructor Detail

MultiRowRangeFilter

public MultiRowRangeFilter(List<MultiRowRangeFilter.RowRange> list)
                    throws IOException

Parameters:

list - A list of RowRange

Throws:

IOException - throw an exception if the range list is not in an natural order or any RowRange is invalid

Method Detail

filterAllRemaining

public boolean filterAllRemaining()

Description copied from class: FilterBase

Filters that never filter all remaining can inherit this implementation that never stops the filter early. If this returns true, the scan will terminate. Concrete implementers can signal a failure condition in their code by throwing an IOException.

Overrides:

filterAllRemaining in class FilterBase

Returns:

true to end scan, false to continue.

getRowRanges

public List<MultiRowRangeFilter.RowRange> getRowRanges()

filterRowKey

public boolean filterRowKey(byte[] buffer,
                   int offset,
                   int length)

Description copied from class: FilterBase

Filters that do not filter by row key can inherit this implementation that never filters anything. (ie: returns false). 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(Cell) below. Concrete implementers can signal a failure condition in their code by throwing an IOException.

Overrides:

filterRowKey in class FilterBase

Parameters:

buffer - 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(Cell ignored)

Description copied from class: 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 filterRowKey returns true, filterKeyValue needs to be consistent with it. filterKeyValue can assume that filterRowKey has already been called for the row. 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. Concrete implementers can signal a failure condition in their code by throwing an IOException.

Specified by:

filterKeyValue in class Filter

Parameters:

ignored - the Cell in question

Returns:

code as described below

See Also:

Filter.ReturnCode

getNextCellHint

public Cell getNextCellHint(Cell currentKV)

Description copied from class: FilterBase

Filters that are not sure which key must be next seeked to, can inherit this implementation that, by default, returns a null Cell. If the filter returns the match code SEEK_NEXT_USING_HINT, then it should also tell which is the next key it must seek to. After receiving the match code SEEK_NEXT_USING_HINT, the QueryMatcher would call this function to find out which key it must next seek to. Concrete implementers can signal a failure condition in their code by throwing an IOException.

Overrides:

getNextCellHint in class FilterBase

Returns:

KeyValue which must be next seeked. return null if the filter is not sure which key to seek to next.

toByteArray

public byte[] toByteArray()

Description copied from class: FilterBase

Return length 0 byte array for Filters that don't require special serialization

Overrides:

toByteArray in class FilterBase

Returns:

The filter serialized using pb

parseFrom

public static MultiRowRangeFilter parseFrom(byte[] pbBytes)
                                     throws DeserializationException

Parameters:

pbBytes - A pb serialized instance

Returns:

An instance of MultiRowRangeFilter

Throws:

DeserializationException

sortAndMerge

public static List<MultiRowRangeFilter.RowRange> sortAndMerge(List<MultiRowRangeFilter.RowRange> ranges)

sort the ranges and if the ranges with overlap, then merge them.

Parameters:

ranges - the list of ranges to sort and merge.

Returns:

the ranges after sort and merge.