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https://issues.apache.org/jira/browse/CALCITE-1793?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16014438#comment-16014438
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Chris Baynes commented on CALCITE-1793:
---------------------------------------
After taking another look at this I've realised it could be a problem with the
jdbc adapter for the extract function.
Direct execution of the `select extract(year from date '2008-2-23') from
"foodmart"."employee"` fails with:
{code}
Caused by: java.lang.UnsupportedOperationException: class
org.apache.calcite.sql.SqlSyntax$6: SPECIAL
at org.apache.calcite.util.Util.needToImplement(Util.java:925)
at org.apache.calcite.sql.SqlSyntax$6.unparse(SqlSyntax.java:116)
{code}
>From my understanding EXTRACT is converted to an EXTRACT_DATE containing a
>literal and a reinterpret.
EXTRACT has an unparse method which is called in the preparation & validation
phases and works fine.
EXTRACT_DATE.unparse is eventually called by
JdbcToEnumerableConverter.generateSql which raises the above exception.
What's the reason for converting the extract -> extract_date? Seems like this
should be an extract op before converting to sql which gets fired off against
the physical db.
JdbcTest.testExtract passes right now since it doesn't use a FROM clause and so
doesn't go through the jdbc converter.
Fixing the EXTRACT_DATE unparse method seems like the wrong thing to do. Do you
have any ideas for the right way to go about fixing this?
> Allow RelBuilder to make calls to EXTRACT
> -----------------------------------------
>
> Key: CALCITE-1793
> URL: https://issues.apache.org/jira/browse/CALCITE-1793
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.11.0, 1.12.0
> Reporter: Chris Baynes
> Assignee: Julian Hyde
> Priority: Minor
>
> EXTRACT_DATE was originally intended to be an internal function, always
> created by translating a call to EXTRACT.
> Currently this makes the EXTRACT_DATE function rather awkward to use:
> {code}
> SqlOperator op = new SqlSpecialOperator("EXTRACT_DATE", SqlKind.EXTRACT, 2,
> true, ReturnTypes.INTEGER, null, null);
> builder.call(op, builder.getRexBuilder().makeFlag(TimeUnitRange.YEAR),
> builder.field(1, 0, "my_date"));
> {code}
> [~julianhyde] suggests calling EXTRACT directly and then have RelBuilder
> invoke a convertlet to translate into calls to EXTRACT_DATE or date-time
> arithmetic.
> Mailing list discussion:
> [http://mail-archives.apache.org/mod_mbox/calcite-dev/201705.mbox/%3CCAPSgeET9OVWkvGsGXAezqhqP3Zd2dmXxs0k-J92WZM32%2BMq3kw%40mail.gmail.com%3E]
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