Class ClientSideIteratorScanner

  • All Implemented Interfaces:
    AutoCloseable, Iterable<Map.Entry<Key,​Value>>, Scanner, ScannerBase

    public class ClientSideIteratorScanner
    extends org.apache.accumulo.core.clientImpl.ScannerOptions
    implements Scanner
    A scanner that instantiates iterators on the client side instead of on the tablet server. This can be useful for testing iterators or in cases where you don't want iterators affecting the performance of tablet servers.

    Suggested usage:

     
     Scanner scanner = client.createScanner(tableName, authorizations);
     scanner = new ClientSideIteratorScanner(scanner);
     
     

    Iterators added to this scanner will be run in the client JVM. Separate scan iterators can be run on the server side and client side by adding iterators to the source scanner (which will execute server side) and to the client side scanner (which will execute client side).

    • Constructor Detail

      • ClientSideIteratorScanner

        public ClientSideIteratorScanner​(Scanner scanner)
        Constructs a scanner that can execute client-side iterators.
        Parameters:
        scanner - the source scanner
    • Method Detail

      • setSource

        public void setSource​(Scanner scanner)
        Sets the source Scanner.
      • iterator

        public Iterator<Map.Entry<Key,​Value>> iterator()
        Description copied from interface: ScannerBase
        Returns an iterator over an accumulo table. This iterator uses the options that are currently set for its lifetime, so setting options will have no effect on existing iterators.

        Keys returned by the iterator are not guaranteed to be in sorted order.

        Specified by:
        iterator in interface Iterable<Map.Entry<Key,​Value>>
        Specified by:
        iterator in interface ScannerBase
        Overrides:
        iterator in class org.apache.accumulo.core.clientImpl.ScannerOptions
        Returns:
        an iterator over Key,Value pairs which meet the restrictions set on the scanner
      • getAuthorizations

        public Authorizations getAuthorizations()
        Description copied from interface: ScannerBase
        Returns the authorizations that have been set on the scanner
        Specified by:
        getAuthorizations in interface ScannerBase
        Overrides:
        getAuthorizations in class org.apache.accumulo.core.clientImpl.ScannerOptions
        Returns:
        The authorizations set on the scanner instance
      • setRange

        public void setRange​(Range range)
        Description copied from interface: Scanner
        Sets the range of keys to scan over.
        Specified by:
        setRange in interface Scanner
        Parameters:
        range - key range to begin and end scan
      • getRange

        public Range getRange()
        Description copied from interface: Scanner
        Returns the range of keys to scan over.
        Specified by:
        getRange in interface Scanner
        Returns:
        the range configured for this scanner
      • setBatchSize

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

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

        public void enableIsolation()
        Description copied from interface: Scanner
        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.
        Specified by:
        enableIsolation in interface Scanner
      • disableIsolation

        public void disableIsolation()
        Description copied from interface: Scanner
        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.
        Specified by:
        disableIsolation in interface Scanner
      • getReadaheadThreshold

        public long getReadaheadThreshold()
        Description copied from interface: Scanner
        The number of batches of Key/Value pairs returned before the Scanner will begin to prefetch the next batch
        Specified by:
        getReadaheadThreshold in interface Scanner
        Returns:
        Number of batches before read-ahead begins
      • setReadaheadThreshold

        public void setReadaheadThreshold​(long batches)
        Description copied from interface: Scanner
        Sets the number of batches of Key/Value pairs returned before the Scanner will begin to prefetch the next batch
        Specified by:
        setReadaheadThreshold in interface Scanner
        Parameters:
        batches - Non-negative number of batches
      • setIteratorSamplerConfiguration

        public void setIteratorSamplerConfiguration​(SamplerConfiguration sc)
        This is provided for the case where no sampler configuration is set on the scanner, but there is a need to create iterator deep copies that have sampling enabled. If sampler configuration is set on the scanner, then this method does not need to be called inorder to create deep copies with sampling.

        Setting this differently than the scanners sampler configuration may cause exceptions.

        Since:
        1.8.0
      • clearIteratorSamplerConfiguration

        public void clearIteratorSamplerConfiguration()
        Clear any iterator sampler configuration.
        Since:
        1.8.0
      • getIteratorSamplerConfiguration

        public SamplerConfiguration getIteratorSamplerConfiguration()
        Returns:
        currently set iterator sampler configuration.
        Since:
        1.8.0
      • close

        public void close()
        Description copied from interface: ScannerBase
        Closes any underlying connections on the scanner. This may invalidate any iterators derived from the Scanner, causing them to throw exceptions.
        Specified by:
        close in interface AutoCloseable
        Specified by:
        close in interface ScannerBase
        Overrides:
        close in class org.apache.accumulo.core.clientImpl.ScannerOptions