...
if (planContract.hasQueryContextInfo())
{
// Conduct input column projection
// This shows an example where input columns needed are
// the output columns projected.
// This is specified in the completePlanningContract method.
List<ColumnDefinition> inputColumnsNeeded =
new ArrayList<ColumnDefinition>();
// add the output columns projected to the input column projection
List<ColumnDefinition> outputColumnsToProject =
qci.getOutputColumnsToProject();
// The planner expects inputColumnsNeeded only when there are
// output columns to project.
// Add a new column from the input that is not in the output
// column projection.
if (!outputColumnsToProject.isEmpty())
{
inputColumnsNeeded = getInputColNotInOutputProjection(outputColumnsToProject);
}
String inputColNameNeeded=null;
if (!inputColumnsNeeded.isEmpty())
{
inputColNameNeeded = inputColumnsNeeded.get(0).getColumnName();
}
HashSet<String> columnNamesAdded = new HashSet<String>();
for (ColumnDefinition colDef: outputColumnsToProject)
{
assert (colDef != null);
// If projection contains column names
// "id", and "number_md5sum",
// the columns needed would be "id" and "number"
String columnName;
if (colDef.getColumnName().endsWith(md5sumSuffix_))
{
columnName = colDef.getColumnName().split(md5sumSuffix_)[0];
}
else
{
columnName = colDef.getColumnName();
}
if (!columnName.equals(inputColNameNeeded)
&& !columnNamesAdded.contains(columnName))
{
Integer inputColIndex = runtimeSchema_.getRuntimeInputIndex(columnName);
assert inputColIndex != null;
ColumnDefinition inputColumn = runtimeSchema_.getInputCols().get(inputColIndex);
inputColumnsNeeded.add(inputColumn);
columnNamesAdded.add(columnName);
}
}
...
InputContext inputContext = new InputContext.Builder()
...
.setInputColumnsNeeded(inputColumnsNeeded)
...
For full context, see Examples.