/**
* 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(IdentifierNamespace.class)) {
IdentifierNamespace identifierNamespace = namespace.unwrap(IdentifierNamespace.class);
final List<String> names = identifierNamespace.getId().names;
if ((datasetName != null) && (catalogReader instanceof RelOptSchemaWithSampling)) {
return ((RelOptSchemaWithSampling) catalogReader)
.getTableForMember(names, datasetName, usedDataset);
} else {
// Schema does not support substitution. Ignore the dataset,
// if any.
return catalogReader.getTableForMember(names);
}
} else {
return null;
}
}
