[HIVE-17030] HPL/SQL: Many cast operations are ignored without warning or notice.

• Type: Bug
• Status: Patch Available
• Priority: Critical
• Resolution: Unresolved
• Component/s: hpl/sql
• Assignee: Dmitry Tolpeko
• Reporter: Carter Shanklin
• Created: 04/Jul/17 21:21
• Updated: 09/Sep/17 00:37

Description

This bug is part of a series of issues and surprising behavior I encountered writing a reporting script that would aggregate values and give rows different classifications based on an the aggregate. Addressing some or all of these issues would make HPL/SQL more accessible to newcomers.

Consider this code:

  val1d := cast('10.0' as double);
  val2d := cast('5.0' as double);
  declare val1i int = 5;
  declare val2i int = 5;
  val1i = val1d;
  diff := val1i - val2i;

What is the value of diff? You might think it is 5 but in fact it is 0. Why? Because when you attempt to assign val1i to val1d, this code in Var.java is executed:

    else if (type == Type.BIGINT) {
      if (val.type == Type.STRING) {
        value = Long.parseLong((String)val.value);
      }
    }
    else if (type == Type.DECIMAL) {

Since there is no case for assigning a double to a bigint, the expression is essentially ignored and the value remains the same. This behavior leads to many surprising results.

It would be best if HPL/SQL could re-use the cast code from Hive since there are a lot of cases to consider.

Version = 3.0.0-SNAPSHOT r71f52d8ad512904b3f2c4f04fe39a33f2834f1f2