Package org.apache.hadoop.hbase.filter

Class ColumnPaginationFilter

java.lang.Object
org.apache.hadoop.hbase.filter.Filter
org.apache.hadoop.hbase.filter.FilterBase
org.apache.hadoop.hbase.filter.ColumnPaginationFilter
@Public public class ColumnPaginationFilter extends FilterBase
A filter, based on the ColumnCountGetFilter, takes two arguments: limit and offset. This filter can be used for row-based indexing, where references to other tables are stored across many columns, in order to efficient lookups and paginated results for end users. Only most recent versions are considered for pagination.
API Note:
This filter is in awkward place, as even though it can return SEEK_NEXT_USING_HINT, it also maintains an internal row state, so it is not marked as HintingFilter. Hinted seek information may be lost when used in a MUST_PASS_ALL FilterList, which can result in suboptimal performance.

  • Field Details

  • Constructor Details

    • ColumnPaginationFilter

      public ColumnPaginationFilter(int limit, int offset)
      Initializes filter with an integer offset and limit. The offset is arrived at scanning sequentially and skipping entries. @limit number of columns are then retrieved. If multiple column families are involved, the columns may be spread across them.
      Parameters:
      limit - Max number of columns to return.
      offset - The integer offset where to start pagination.

    • ColumnPaginationFilter

      public ColumnPaginationFilter(int limit, byte[] columnOffset)
      Initializes filter with a string/bookmark based offset and limit. The offset is arrived at, by seeking to it using scanner hints. If multiple column families are involved, pagination starts at the first column family which contains @columnOffset. Columns are then retrieved sequentially upto @limit number of columns which maybe spread across multiple column families, depending on how the scan is setup.
      Parameters:
      limit - Max number of columns to return.
      columnOffset - The string/bookmark offset on where to start pagination.

  • Method Details

    • getLimit

      public int getLimit()

    • getOffset

      public int getOffset()

    • getColumnOffset

      public byte[] getColumnOffset()

    • 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:

    • getNextCellHint

      public Cell getNextCellHint(Cell cell)
      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. NOTICE: Filter will be evaluate at server side so the returned Cell must be an ExtendedCell, although it is marked as IA.Private.
      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.

    • 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

    • createFilterFromArguments

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

    • toByteArray

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

    • parseFrom

      public static ColumnPaginationFilter parseFrom(byte[] pbBytes) throws DeserializationException
      Parse a serialized representation of ColumnPaginationFilter
      Parameters:
      pbBytes - A pb serialized ColumnPaginationFilter instance
      Returns:
      An instance of ColumnPaginationFilter 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.

    • toString

      public String toString()
      Description copied from class: FilterBase
      Return filter's info for debugging and logging purpose.
      Overrides:
      toString in class FilterBase

    • equals

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

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object