Package org.apache.hadoop.hbase.filter

Class FirstKeyOnlyFilter

java.lang.Object
org.apache.hadoop.hbase.filter.Filter
org.apache.hadoop.hbase.filter.FilterBase
org.apache.hadoop.hbase.filter.FirstKeyOnlyFilter
@Public public class FirstKeyOnlyFilter extends FilterBase
A filter that will only return the first KV from each row.

This filter can be used to more efficiently perform row count operations.

  • Field Details

    • foundKV

      private boolean foundKV

  • Constructor Details

  • Method Details

    • reset

      public void reset()
      Description copied from class: FilterBase
      Filters that are purely stateless and do nothing in their reset() methods can inherit this null/empty implementation. Reset the state of the filter between rows. Concrete implementers can signal a failure condition in their code by throwing an IOException.
      Overrides:
      reset in class FilterBase

    • filterRowKey

      public boolean filterRowKey(Cell cell) throws IOException
      Description copied from class: 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.filterCell(Cell) below. If Filter.filterAllRemaining() returns true, then Filter.filterRowKey(Cell) should also return true. Concrete implementers can signal a failure condition in their code by throwing an IOException.
      Overrides:
      filterRowKey in class FilterBase
      Parameters:
      cell - The first cell coming in the new row
      Returns:
      true, remove entire row, false, include the row (maybe).
      Throws:
      IOException - in case an I/O or an filter specific failure needs to be signaled.

    • filterCell

      public Filter.ReturnCode filterCell(Cell c)
      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, filterCell needs to be consistent with it. filterCell 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.
      Overrides:
      filterCell in class Filter
      Parameters:
      c - the Cell in question
      Returns:
      code as described below
      See Also:

    • createFilterFromArguments

      public static Filter createFilterFromArguments(ArrayList<byte[]> filterArguments)

    • hasFoundKV

      protected boolean hasFoundKV()
      Returns true if first KV has been found.

    • setFoundKV

      protected void setFoundKV(boolean value)
      Set or clear the indication if the first KV has been found.
      Parameters:
      value - update foundKV flag with value.

    • toByteArray

      public byte[] toByteArray()
      Returns The filter serialized using pb
      Overrides:
      toByteArray in class FilterBase
      Returns:
      The filter serialized using pb

    • parseFrom

      public static FirstKeyOnlyFilter parseFrom(byte[] pbBytes) throws DeserializationException
      Parse a serialized representation of FirstKeyOnlyFilter
      Parameters:
      pbBytes - A pb serialized FirstKeyOnlyFilter instance
      Returns:
      An instance of FirstKeyOnlyFilter made from bytes
      Throws:
      DeserializationException - if an error occurred
      See Also:

    • areSerializedFieldsEqual

      boolean areSerializedFieldsEqual(Filter o)
      Returns true if and only if the fields of the filter that are serialized are equal to the corresponding fields in other. Used for testing.
      Overrides:
      areSerializedFieldsEqual in class FilterBase
      Returns:
      true if and only if the fields of the filter that are serialized are equal to the corresponding fields in other. Used for testing.

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object