/**
* Converts a {@link SqlValidatorScope} into a {@link RelOptTable}. This is only possible if the
* scope represents an identifier, such as "sales.emp". Otherwise, returns null.
*
* @param namespace Namespace
* @param catalogReader Schema
* @param datasetName Name of sample dataset to substitute, or null to use the regular table
* @param usedDataset Output parameter which is set to true if a sample dataset is found; may be
* null
*/
public static RelOptTable getRelOptTable(
SqlValidatorNamespace namespace,
Prepare.CatalogReader catalogReader,
String datasetName,
boolean[] usedDataset) {
if (!namespace.isWrapperFor(TableNamespace.class)) {
return null;
}
final TableNamespace tableNamespace = namespace.unwrap(TableNamespace.class);
final List<String> names = tableNamespace.getTable().getQualifiedName();
RelOptTable table;
if (datasetName != null && catalogReader instanceof RelOptSchemaWithSampling) {
final RelOptSchemaWithSampling reader = (RelOptSchemaWithSampling) catalogReader;
table = reader.getTableForMember(names, datasetName, usedDataset);
} else {
// Schema does not support substitution. Ignore the data set, if any.
table = catalogReader.getTableForMember(names);
}
if (!tableNamespace.extendedFields.isEmpty()) {
table = table.extend(tableNamespace.extendedFields);
}
return table;
}
