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From Julian Hyde <jh...@apache.org>
Subject Re: Deterministic behavior of Negative Function?
Date Tue, 02 Feb 2016 17:12:38 GMT
I don’t recall interval literals being discussed on the Calcite list. We do support interval
literals of the standard types (day-to-second or year-to-month) but we don’t support interval
literals (or interval values) of month-to-day type. I think there’s a good reason that that
kind of literal isn’t in standard SQL - it is not very well-defined how to add such an interval
to a date (or how to create one by subtracting two dates).

There are a lot of assumptions-on-assumptions in this case. It would be helpful if there were
JIRA cases were logged for missing functionality (even if we don’t end up adding that functionality).


> On Feb 2, 2016, at 7:33 AM, Jason Altekruse <altekrusejason@gmail.com> wrote:
> I made this change. It was a bit of a hack to re-use the non-deterministic
> property as an indication if a function could be folded into a constant.
> If you look at the definition of that list of NON_REDUCIBLE_TYPES constant,
> explanations are given for why given types are included.
> The problem with the INTERVAL type is that Calcite did not allow creating a
> literal for this format. I believe this was intentional, so I didn't bother
> opening a Calcite JIRA. The issue is that our interval type spans across
> months and days, which I wasn't even sure how to interpret. I could not
> find an example of this type in other databases, see docs linked for
> examples in SQL Server and Oracle. [1] [2] Both of these systems support
> intervals that span across years and months or days/millis, and both of
> these Drill types are supported by the constant folding rule.
> [1] -
> http://docs.oracle.com/cd/E11882_01/server.112/e41084/sql_elements001.htm#SQLRF30020
> [2] - https://msdn.microsoft.com/en-us/library/ms716506%28v=vs.85%29.aspx
> On Tue, Feb 2, 2016 at 6:11 AM, Jacques Nadeau <jacques@dremio.com> wrote:
>> What jira was this change added with?
>> On Feb 1, 2016 11:42 PM, "Hsuan Yi Chu" <hyichu@maprtech.com> wrote:
>>> All the variants of Negative DrillFuncHolder are supposed to be
>>> deterministic. However, when they are being registered
>>> into DrillOperatorTable, there is a if-statement:
>>> https://github.com/apache/drill/blob/master/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/DrillFunctionRegistry.java#L116
>>> which claims DrillFuncHolder being non-deterministic when return type is
>>> Interval. Why it is necessary to have this if-condition?
>>> -------------------------
>>> Making DrillFuncHolder non-deterministic will prevent partition-pruing or
>>> constant folding from happening.

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