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https://issues.apache.org/jira/browse/CALCITE-1003?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15049043#comment-15049043
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Julian Hyde commented on CALCITE-1003:
--------------------------------------
Regarding LIMIT versus FETCH. Is that a change you think you'll make in the
next day or so? If so I'll wait for it before committing. If not, please log a
jira case.
I agree that the support is patchy. LIMIT is more common but FETCH is the
standard. We should support both, and the dialect should know what each
database supports (not SqlSelectOperator as you have it now). To make this
concrete, can you suggest a database that only supports LIMIT? Let's add a test
where we generate SQL for that database.
> 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 <[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:
> {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 <[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
> {quote}
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