| Access | Constructor and Description |
|---|---|
| pack-priv | MergeScanRowSource(MergeSort sort, TransactionManager tran, SortBuffer sortBuffer, Vector<Long> mergeRuns, SortObserver sortObserver, boolean hold)
|
| Modifier and Type | Method and Description |
|---|---|
| public void | closeRowSource()
Implements org. Close the row source - implemented by MergeScan already |
| public DataValueDescriptor[] | getNextRowFromRowSource()
Implements org. Get the next row as an array of column objects. |
| public FormatableBitSet | getValidColumns()
Implements org. All columns are always set from a sorter |
| public boolean | needsRowLocation()
Implements org. needsRowLocation returns true iff this the row source expects the drainer of the row source to call rowLocation after getting a row from getNextRowFromRowSource. |
| public boolean | |
| public boolean | needsToClone()
Implements org. 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. |
| public boolean | next()
Overrides org. Implements org. Move to the next position in the scan. |
| public void | offendingRowLocation(RowLocation rl, long containdId)
Implements org.
|
| public void | rowLocation(RowLocation rl)
Implements org. 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. |
| MergeScanRowSource | back to summary |
|---|---|
| pack-priv MergeScanRowSource(MergeSort sort, TransactionManager tran, SortBuffer sortBuffer, Vector<Long> mergeRuns, SortObserver sortObserver, boolean hold) | |
| closeRowSource | back to summary |
|---|---|
| public void closeRowSource() Implements org. Close the row source - implemented by MergeScan already | |
| getNextRowFromRowSource | back to summary |
|---|---|
| public DataValueDescriptor[] getNextRowFromRowSource() throws StandardException Implements org. Doc from org. 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 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().
| |
| getValidColumns | back to summary |
|---|---|
| public FormatableBitSet getValidColumns() Implements org. All columns are always set from a sorter | |
| needsRowLocation | back to summary |
|---|---|
| public boolean needsRowLocation() Implements org. Doc from org. needsRowLocation returns true iff this the row source expects the drainer of the row source to call rowLocation after getting a row from getNextRowFromRowSource.
| |
| needsRowLocationForDeferredCheckConstraints | back to summary |
|---|---|
| public boolean needsRowLocationForDeferredCheckConstraints() Implements org. | |
| needsToClone | back to summary |
|---|---|
| public boolean needsToClone() Implements org. Doc from org. 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). | |
| next | back to summary |
|---|---|
| public boolean next() throws StandardException Overrides org. Implements org. Doc from org. Move to the next position in the scan. If this is the first call to next(), the position is set to the first row. Returns false if there is not a next row to move to. It is possible, but not guaranteed, that this method could return true again, after returning false, if some other operation in the same transaction appended a row to the underlying conglomerate.
| |
| offendingRowLocation | back to summary |
|---|---|
| public void offendingRowLocation(RowLocation rl, long containdId) throws StandardException Implements org. | |
| rowLocation | back to summary |
|---|---|
| public void rowLocation(RowLocation rl) Implements org. Doc from org. 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).
| |