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From Julian Hyde <jh...@apache.org>
Subject Re: RelNode to SQLNode converter
Date Tue, 01 Dec 2015 21:43:02 GMT
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 <amoghm@qubole.com> 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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