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 Details

    • 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