Using Iterators - Aster Execution Engine

//
// Initialize the vertex key from the partition definition structure.
//
VertexKey vertexKey = new VertexKey(inputs.getPartitionDefinition());
HelloWorldVertex vertex = new HelloWorldVertex(vertexKey);
vertexState.addVertex(vertex);
System.out.println("   -----------------------------------------------------");
// Examine rows from input relation "etable"
RowIterator etable_inputsIterator = inputs.getRowIterator("etable");
int i=0;
// TODO: do something with this row iterator, i.e. fetch certain columns value.
System.out.println("   etable column count: " + etable_inputsIterator.getColumnCount());
System.out.println();
RowHolder rowHolder;
VertexKey targetVertexKey;
if (etable_inputsIterator.advanceToNextRow()){
	// Get the column count of etable
	System.out.println("   Source Node  |  Destination Node");
	do {
		// Create a row and add to it the id of the target vertex.
		rowHolder = new RowHolder(SqlType.integer());
		// Display the input row contents.
		System.out.println("   " + etable_inputsIterator.getIntAt(1)+ 				"               "+etable_inputsIterator.getIntAt(2));
		rowHolder.setIntAt(0, etable_inputsIterator.getIntAt(2));
		targetVertexKey = new VertexKey(rowHolder);
		System.out.println("Adding edge to vertexState...");
		vertexState.addEdge(new Edge(targetVertexKey));
		i++;
	} while (etable_inputsIterator.advanceToNextRow());
} // end if
// Examine rows from input relation "vtable."
RowIterator vtable_inputsIterator = inputs.getRowIterator("vtable");
// TODO: do something with this row iterator, i.e. fetch certain columns value.
if (vtable_inputsIterator.advanceToNextRow()){
	System.out.println();
	System.out.println("   " + i +  		" edge(s) go out from this vertex (" +  		vtable_inputsIterator.getStringAt(1) + ")");
	System.out.println("   -----------------------------------------------------");
	System.out.println();
}