Amogh Margoor created CALCITE-1003:
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             Summary: Add Utility to convert RelNode to SqlNode
                 Key: CALCITE-1003
                 URL: https://issues.apache.org/jira/browse/CALCITE-1003
             Project: Calcite
          Issue Type: Improvement
          Components: core
            Reporter: Amogh Margoor
            Assignee: Julian Hyde
            Priority: Minor
             Fix For: next


To track progress on Rel2Sql Converter.
Following is the email conversation that lead to this JIRA:

On Wed, Dec 2, 2015 at 3:13 AM, Julian Hyde <[email protected]> wrote:

    Yes, this would definitely be useful in Calcite. Thanks for offering.

    I would like to reduce the amount of code copy-pasted from the JdbcXxx 
relational expressions, but we can work on that after it is committed in and 
when there are some unit tests.

    Can you please create a JIRA case with an initial pull-request?

    I think the unit tests could be of the following form:

      @Test public void testScan() {
        final String sql = “select * from emp”;
        final String after = "SELECT *\n”
            + "FROM \”EMP\””;
        check(sql, after);
      }

    where “after” is the result of the round trip SQL -> SqlNode -> RelNode -> 
SqlNode -> SQL, and your utility is performing the 3rd “->”.

    Julian

    > On Dec 1, 2015, at 12:28 AM, Amogh Margoor <[email protected]> wrote:
    >
    > Hi,
    > We have an usecase where we need to just send back optimized query as SQL,
    > without executing it. So we needed an utility to convert RelNode back to
    > SQL, and found most of the logic to be in JDBCRel. As we needed it for non
    > JDBC source, we created an utility to do so:
    > 
https://github.com/amoghmargoor/incubator-calcite/blob/NEZ-52/core/src/main/java/org/apache/calcite/rel/rel2sql/RelToSqlConverter.java
    >
    > Utility is almost completely copy-pasted from JDBCRels with few fixes from
    > our side to make it work. If such utility will be useful in Calcite then
    > let us know, we can plan raising PRs with required UTs.
    >
    > Regards,
    > Amogh




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