Method isConstant

fe/src/main/java/org/apache/impala/analysis/Expr.java:1547–1550

Returns true if this expression should be treated as constant. I.e. if the frontend and backend should assume that two evaluations of the expression within a query will return the same value. Examples of constant expressions include: - Literal values like 1, "foo", or NULL - Deterministic operators

()

   * FunctionCallExpr.isConstant()).
   */
  public final boolean isConstant() {
    if (isAnalyzed_) return isConstant_;
    return isConstantImpl();
  }

  /**
   * Implements isConstant() - computes the value without using 'isConstant_'.