case UNNEST:
// Get unnest item property.
UnnestOperator unnest = (UnnestOperator) op;
ILogicalExpression unnestLogicalExpression = (ILogicalExpression) unnest.getExpressionRef().getValue();
variableId = unnest.getVariables().get(0).getId();
Cardinality inputCardinality = vxqueryContext.getCardinalityOperatorMap(op.getInputs().get(0)
.getValue());
documentOrder = propagateDocumentOrder(unnestLogicalExpression, documentOrderVariablesForOperator);
uniqueNodes = propagateUniqueNodes(unnestLogicalExpression, uniqueNodesVariablesForOperator);
// Reset properties based on unnest duplication.