Constructor Detail

• MergeScanRowSource

  MergeScanRowSource​(MergeSort sort,
                     TransactionManager tran,
                     SortBuffer sortBuffer,
                     java.util.Vector<java.lang.Long> mergeRuns,
                     SortObserver sortObserver,
                     boolean hold)

Method Detail

• next

  public boolean next()
               throws StandardException

  Description copied from class: MergeScan
  Move to the next position in the scan.

  Specified by:

  next in interface GroupFetchScanController

  Specified by:

  next in interface ScanController

  Overrides:

  next in class MergeScan

  Returns:

  True if there is a next position in the scan, false if there isn't.

  Throws:

  StandardException - Standard exception policy.

  See Also:

  ScanController.next()

• getNextRowFromRowSource

  public DataValueDescriptor[] getNextRowFromRowSource()
                                                throws StandardException

  Description copied from interface: RowSource
  Get the next row as an array of column objects. The column objects can be a JBMS Storable or any Serializable/Externalizable/Formattable/Streaming type.
  A return of null indicates that the complete set of rows has been read.

  A null column can be specified by leaving the object null, or indicated by returning a non-null getValidColumns. On streaming columns, it can be indicated by returning a non-null get FieldStates.

  If RowSource.needToClone() is true then the returned row (the DataValueDescriptor[]) is guaranteed not to be modified by drainer of the RowSource (except that the input stream will be read, of course) and drainer will keep no reference to it before making the subsequent nextRow call. So it is safe to return the same DataValueDescriptor[] in subsequent nextRow calls if that is desirable for performance reasons.

  If RowSource.needToClone() is false then the returned row (the DataValueDescriptor[]) may be be modified by drainer of the RowSource, and the drainer may keep a reference to it after making the subsequent nextRow call. In this case the client should severe all references to the row after returning it from getNextRowFromRowSource().

  Specified by:

  getNextRowFromRowSource in interface RowSource

  Throws:

  StandardException - Standard Derby Error Policy

• needsRowLocation

  public boolean needsRowLocation()

  Description copied from interface: RowLocationRetRowSource
  needsRowLocation returns true iff this the row source expects the drainer of the row source to call rowLocation after getting a row from getNextRowFromRowSource.

  Specified by:

  needsRowLocation in interface RowLocationRetRowSource

  Returns:

  true iff this row source expects some row location to be returned

  See Also:

  RowLocationRetRowSource.needsRowLocation()

• needsRowLocationForDeferredCheckConstraints

  public boolean needsRowLocationForDeferredCheckConstraints()

  Specified by:

  needsRowLocationForDeferredCheckConstraints in interface RowLocationRetRowSource

• needsToClone

  public boolean needsToClone()

  Description copied from interface: RowSource
  Does the caller of getNextRowFromRowSource() need to clone the row in order to keep a reference to the row past the getNextRowFromRowSource() call which returned the row. This call must always return the same for all rows in a RowSource (ie. the caller will call this once per scan from a RowSource and assume the behavior is true for all rows in the RowSource).

  Specified by:

  needsToClone in interface RowSource

  See Also:

  RowSource.needsToClone()

• rowLocation

  public void rowLocation​(RowLocation rl)

  Description copied from interface: RowLocationRetRowSource
  rowLocation is a callback for the drainer of the row source to return the rowLocation of the current row, i.e, the row that is being returned by getNextRowFromRowSource. This interface is for the purpose of loading a base table with index. In that case, the indices can be built at the same time the base table is laid down once the row location of the base row is known. This is an example pseudo code on how this call is expected to be used:
  

                  boolean needsRL = rowSource.needsRowLocation();
                  DataValueDescriptor[] row;
                  while((row = rowSource.getNextRowFromRowSource()) != null)
                  {
                          RowLocation rl = heapConglomerate.insertRow(row);
                          if (needsRL)
                                  rowSource.rowLocation(rl);
                  }
                  

  
  NeedsRowLocation and rowLocation will ONLY be called by a drainer of the row source which CAN return a row location. Drainer of row source which cannot return rowLocation will guarantee to not call either callbacks. Conversely, if NeedsRowLocation is called and it returns true, then for every row return by getNextRowFromRowSource, a rowLocation callback must also be issued with the row location of the row. Implementor of both the source and the drain of the row source must be aware of this protocol.
  The RowLocation object is own by the caller of rowLocation, in other words, the drainer of the RowSource. This is so that we don't need to new a row location for every row. If the Row Source wants to keep the row location, it needs to clone it (RowLocation is a ClonableObject).

  Specified by:

  rowLocation in interface RowLocationRetRowSource

  See Also:

  RowLocationRetRowSource.rowLocation(org.apache.derby.iapi.types.RowLocation)

• offendingRowLocation

  public void offendingRowLocation​(RowLocation rl,
                                   long containdId)
                            throws StandardException

  Specified by:

  offendingRowLocation in interface RowLocationRetRowSource

  Throws:

  StandardException

• getValidColumns

  public FormatableBitSet getValidColumns()

  All columns are always set from a sorter

  Specified by:

  getValidColumns in interface RowSource

• closeRowSource

  public void closeRowSource()

  Close the row source - implemented by MergeScan already

  Specified by:

  closeRowSource in interface RowSource