[jira] [Created] (IMPALA-7900) Constant SELECT stmt base table expression is inconsistent

["Paul Rogers (JIRA)" <ji...@apache.org>]

Paul Rogers created IMPALA-7900:
-----------------------------------

             Summary: Constant SELECT stmt base table expression is inconsistent
                 Key: IMPALA-7900
                 URL: https://issues.apache.org/jira/browse/IMPALA-7900
             Project: IMPALA
          Issue Type: Bug
          Components: Frontend
    Affects Versions: Impala 3.0
            Reporter: Paul Rogers
            Assignee: Paul Rogers


A SELECT statement has three independent copies of the SELECT list expressions:

* The SELECT list itself, as provided by the parser
* The result expressions, which represents the output tuple
* The Base table result expressions, maintained by the QueryStmt

When using a constant expression, the base table list is out of sync with the other two:

{code:java}
      String query = "SELECT 1 + 1 AS c" +
          " from functional.alltypestiny";
      AnalysisContext ctx = createAnalysisCtx();
      ctx.getQueryOptions().setEnable_expr_rewrites(true);
      SelectStmt select = (SelectStmt) AnalyzesOk(query, ctx);
      Expr selectExpr = select.getSelectList().getItems().get(0).getExpr();
      assertEquals(ScalarType.SMALLINT, selectExpr.getType());
      Expr resultExpr = select.getResultExprs().get(0);
      assertEquals(ScalarType.SMALLINT, resultExpr.getType());
      Expr baseTableExpr = select.getBaseTblResultExprs().get(0);
      // Fails
      assertEquals(ScalarType.SMALLINT, baseTableExpr.getType());
{code}

The last assertion above fails with:

{noformat}
Expected: SMALLINT but was: TINYINT
{noformat}

This error does not occur if rewrites are disabled:

{code:java}
      ctx.getQueryOptions().setEnable_expr_rewrites(false);
{code}

It is not clear if the BE needs the information that is incorrect. But, to reduce cognitive load on developers, things should be consistent.



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