Class Path

fe/src/main/java/org/apache/impala/analysis/Path.java:117–657

Represents a resolved or unresolved dot-separated path that is rooted at a registered tuple descriptor, catalog table/view, or an existing resolved path. This class implements the resolution logic for mapping an implicit or explicit raw path to the corresponding physical types/positions in the sche

 * of the query block that it is used in.
 */
public class Path {
  private final static Logger LOG = LoggerFactory.getLogger(Path.class);

  // Implicit field names of collections.
  public static final String ARRAY_ITEM_FIELD_NAME = "item";
  public static final String ARRAY_POS_FIELD_NAME = "pos";
  public static final String MAP_KEY_FIELD_NAME = "key";
  public static final String MAP_VALUE_FIELD_NAME = "value";

  public static enum PathType {
    SLOT_REF,
    TABLE_REF,
    STAR,
    ANY, // Reference to any field or table in schema.
  }

  // Implicit or explicit raw path to be resolved relative to rootDesc_ or rootTable_.
  // Every raw-path element is mapped to zero, one or two types/positions in resolution.
  private final List<String> rawPath_;

  // Registered table alias that this path is rooted at, if any.
  // Null if the path is rooted at a catalog table/view.
  // Note that this is also set for STAR path of "v.*" when "v" is a catalog table/view.
  private final TupleDescriptor rootDesc_;

  // Catalog table that this resolved path is rooted at, if any.
  // Null if the path is rooted at a registered tuple that does not
  // belong to a catalog table/view.
  private final FeTable rootTable_;

  // Root path that a relative path was created from.
  private final Path rootPath_;

  // List of matched types and field positions set during resolution. The matched
  // types/positions describe the physical path through the schema tree of a catalog
  // table/view. Empty if the path corresponds to a catalog table/view, e.g. when it's a
  // TABLE_REF or when it's a STAR on a table/view.
  private final List<Type> matchedTypes_ = new ArrayList<>();
  private final List<Integer> matchedPositions_ = new ArrayList<>();

  // Remembers the indices into rawPath_ and matchedTypes_ of the first collection
  // matched during resolution.
  private int firstCollectionPathIdx_ = -1;
  private int firstCollectionTypeIdx_ = -1;

  // Indicates whether this path has been resolved. Set in resolve().
  private boolean isResolved_ = false;

  // Caches the result of getAbsolutePath() to avoid re-computing it.
  private List<Integer> absolutePath_ = null;

  private TVirtualColumnType virtualColType_ = TVirtualColumnType.NONE;

  // Resolved path before we resolved it again inside the table masking view.
  private Path pathBeforeMasking_ = null;

  // Fully-qualified raw path. Populated on first call to getFullyQualifiedRawPath.
  // Its inputs are all private final fields, so value can't change after init.