public interface RowSource
A RowSource can come from many sources - from rows that are from fast path import, to rows coming out of a sort for index creation.
Modifier and Type | Method and Description |
---|---|
void |
closeRowSource()
closeRowSource tells the RowSource that it will no longer need to
return any rows and it can release any resource it may have.
|
DataValueDescriptor[] |
getNextRowFromRowSource()
Get the next row as an array of column objects.
|
FormatableBitSet |
getValidColumns()
getValidColumns describes the DataValueDescriptor[] returned by all calls
to the getNextRowFromRowSource() call.
|
boolean |
needsToClone()
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.
|
DataValueDescriptor[] getNextRowFromRowSource() throws StandardException
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().
StandardException
- Standard Derby Error Policyboolean needsToClone()
FormatableBitSet getValidColumns()
void closeRowSource()
Apache Derby V10.13 Internals - Copyright © 2004,2016 The Apache Software Foundation. All Rights Reserved.