[jira] [Created] (CALCITE-582) EnumerableTableScan broken when table has single column

["Julian Hyde (JIRA)" <ji...@apache.org>]

Julian Hyde created CALCITE-582:
-----------------------------------

             Summary: EnumerableTableScan broken when table has single column
                 Key: CALCITE-582
                 URL: https://issues.apache.org/jira/browse/CALCITE-582
             Project: Calcite
          Issue Type: Bug
            Reporter: Julian Hyde
            Assignee: Julian Hyde


Vladimir writes:

{quote}The release brings regression in terms of
AbstractQueryableTable(Object[]) vs EnumerableTableScan interaction.

I am not sure what is the best way to solve it.

I suspect EnumerableTableScan users are impacted.

Historically, Calcite treated AbstractQueryableTable(Object[].class)
in a tricky way:
1) If the row type has more than one column, then Calcite expects
Enumerator<Object[]>
2) If the row type has just a single column, then Calcite expects
"unboxed Object[]".

In  CALCITE-488 this behavior was broken so for Object[].class tables
Calcite always expects Object[] boxed rows.
>From one view this new behavior is "less surprising", however the
change was not intended.

For instance, smart-csv-example is broken since it tries to use
adaptive enumerator type depending on the number of projected columns.
In particular, the change impacts my mat-calcite-plugin and I have no
idea how I missed that when I was testing previous RC.

I would suggest revert to the old mode when Object[].class kind of
tables skip Object[] array for single-column rows.

Well, the PhysType vs elementType API should be improved, however I
would not want that improvement to hold the train.{quote}

And further:

{quote}Here's additional test case:
https://github.com/vlsi/incubator-calcite/commit/f8ec9591ee6be3ce670dfeeb7ff076ae0c9f1345

testModelCustomTableArrayRowSingleColumn breaks with
java.lang.ClassCastException: java.lang.Integer cannot be cast to
[Ljava.lang.Object;
at Baz$1.apply(ANONYMOUS.java:11)

A naive fix (https://github.com/vlsi/incubator-calcite/commit/20d274c0526499cf06e0e61c6d49faf5a8ae7296)
breaks ScannableTable: it looks like scan always returns Object[],
however EnumerableTableScan requires scalars for single columns.{quote}



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