[HIVE-17029] HPL/SQL: Comparison if not null-safe

• Type: Bug
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Component/s: hpl/sql
• Assignee: Dmitry Tolpeko
• Reporter: Carter Shanklin
• Created: 04/Jul/17 21:21
• Updated: 07/Sep/17 16:48

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.

If you run a statement like:

  if val1i > val2i then
    print('val1 greater');
  end if;

And either val1 or val2 is null, you will get an exception similar to the following:

Unhandled exception in HPL/SQL
java.lang.NullPointerException
        at org.apache.hive.hplsql.Var.compareTo(Var.java:453)
        at org.apache.hive.hplsql.Expression.operatorCompare(Expression.java:454)
        at org.apache.hive.hplsql.Expression.execBoolBinary(Expression.java:178)
        at org.apache.hive.hplsql.Exec.visitBool_expr_binary(Exec.java:1589)
        at org.apache.hive.hplsql.Exec.visitBool_expr_binary(Exec.java:52)
        at org.apache.hive.hplsql.HplsqlParser$Bool_expr_binaryContext.accept(HplsqlParser.java:19397)
        at org.antlr.v4.runtime.tree.AbstractParseTreeVisitor.visitChildren(AbstractParseTreeVisitor.java:70)
        at org.apache.hive.hplsql.HplsqlBaseVisitor.visitBool_expr_atom(HplsqlBaseVisitor.java:1316)
        at org.apache.hive.hplsql.HplsqlParser$Bool_expr_atomContext.accept(HplsqlParser.java:18985)
        at org.antlr.v4.runtime.tree.AbstractParseTreeVisitor.visit(AbstractParseTreeVisitor.java:42)
        at org.apache.hive.hplsql.Expression.visit(Expression.java:660)
        at org.apache.hive.hplsql.Expression.eval(Expression.java:624)
        at org.apache.hive.hplsql.Expression.execBool(Expression.java:121)