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https://issues.apache.org/jira/browse/CALCITE-1003?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15048299#comment-15048299
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Amogh Margoor commented on CALCITE-1003:
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Sorry for the delay, [~julianhyde]. Code looks good to me and tests run just
fine on it. However OFFSET and FETCH needed some changes. I have done those
changes and added UTS for it in this commit:
https://github.com/amoghmargoor/incubator-calcite/commit/d1ec52186d80f07d0b4dae21849b32d64d815dce
PR has been updated by both this commit and your changes.
One small enhancement is still pending for LIMIT. Most databases support LIMIT
keyword instead of FETCH. So we have made change to SqlDialect which sets up a
limit flag and outputs LIMIT keyword instead of FETCH during `unparse` or
pretty-printing. I was not sure if I should club Dialect change with this PR so
have not patched that in.
> 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:
> {quote}
> On Wed, Dec 2, 2015 at 3:13 AM, Julian Hyde <jh...@apache.org> 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:
> {code}
> @Test public void testScan() {
> final String sql = “select * from emp”;
> final String after = "SELECT *\n”
> + "FROM \”EMP\””;
> check(sql, after);
> }
> {code}
> 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 <amo...@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
> {quote}
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