Interface Scanner

  • All Superinterfaces:
    AutoCloseable, Iterable<Map.Entry<Key,​Value>>, ScannerBase
    All Known Implementing Classes:
    ClientSideIteratorScanner, IsolatedScanner

    public interface Scanner
    extends ScannerBase
    Scans a table over a given range. "Clients can iterate over multiple column families, and there are several mechanisms for limiting the rows, columns, and timestamps traversed by a scan. For example, we could restrict [a] scan ... to only produce anchors whose columns match [a] regular expression ..., or to only produce anchors whose timestamps fall within ten days of the current time."
    • Method Detail

      • setRange

        void setRange​(Range range)
        Sets the range of keys to scan over.
        Parameters:
        range - key range to begin and end scan
      • getRange

        Range getRange()
        Returns the range of keys to scan over.
        Returns:
        the range configured for this scanner
      • setBatchSize

        void setBatchSize​(int size)
        Sets the number of Key/Value pairs that will be fetched at a time from a tablet server.
        Parameters:
        size - the number of Key/Value pairs to fetch per call to Accumulo
      • getBatchSize

        int getBatchSize()
        Returns the batch size (number of Key/Value pairs) that will be fetched at a time from a tablet server.
        Returns:
        the batch size configured for this scanner
      • enableIsolation

        void enableIsolation()
        Enables row isolation. Writes that occur to a row after a scan of that row has begun will not be seen if this option is enabled.
      • disableIsolation

        void disableIsolation()
        Disables row isolation. Writes that occur to a row after a scan of that row has begun may be seen if this option is enabled.
      • getReadaheadThreshold

        long getReadaheadThreshold()
        The number of batches of Key/Value pairs returned before the Scanner will begin to prefetch the next batch
        Returns:
        Number of batches before read-ahead begins
        Since:
        1.6.0
      • setReadaheadThreshold

        void setReadaheadThreshold​(long batches)
        Sets the number of batches of Key/Value pairs returned before the Scanner will begin to prefetch the next batch
        Parameters:
        batches - Non-negative number of batches
        Since:
        1.6.0