Class View

fe/src/main/java/org/apache/impala/catalog/View.java:47–206

Table metadata representing a catalog view or a local view from a WITH clause. Most methods inherited from Table are not supposed to be called on this class because views are substituted with their underlying definition during analysis of a statement. Refreshing or invalidating a view will reload t

 * affect the metadata of the underlying tables (if any).
 */
public class View extends Table implements FeView {

  // View definition created by parsing inlineViewDef_ into a QueryStmt.
  private QueryStmt queryStmt_;

  // Set if this View is from a WITH clause and not persisted in the catalog.
  private final boolean isLocalView_;

  // Set if this View is from a WITH clause with column labels.
  private List<String> colLabels_;

  public View(org.apache.hadoop.hive.metastore.api.Table msTable,
      Db db, String name, String owner) {
    super(msTable, db, name, owner);
    isLocalView_ = false;
  }

  /**
   * C'tor for WITH-clause views that already have a parsed QueryStmt and an optional
   * list of column labels.
   */
  public View(String alias, QueryStmt queryStmt, List<String> colLabels) {
    super(null, null, alias, null);
    isLocalView_ = true;
    queryStmt_ = queryStmt;
    colLabels_ = colLabels;
  }

  /**
   * Creates a view for testing purposes.
   */
  private View(Db db, String name, QueryStmt queryStmt) {
    super(null, db, name, null);
    isLocalView_ = false;
    queryStmt_ = queryStmt;
    colLabels_ = null;
  }

  @Override
  public void load(boolean reuseMetadata, IMetaStoreClient client,
      org.apache.hadoop.hive.metastore.api.Table msTbl, String reason,
      EventSequence catalogTimeline) throws TableLoadingException {
    try {
      Table.LOADING_TABLES.incrementAndGet();
      clearColumns();
      msTable_ = msTbl;
      // Load columns.
      List<FieldSchema> fieldSchemas = client.getFields(db_.getName(), name_);
      for (int i = 0; i < fieldSchemas.size(); ++i) {
        FieldSchema s = fieldSchemas.get(i);
        Type type = parseColumnType(s);
        Column col = new Column(s.getName(), type, s.getComment(), i);
        addColumn(col);
      }
      // These fields are irrelevant for views.
      numClusteringCols_ = 0;
      tableStats_ = new TTableStats(-1);
      tableStats_.setTotal_file_bytes(-1);