[hibernate-dev] [SEARCH] Remove support for (or deprecate) date/calendar resolution?

[Yoann Rodiere]

> We used it a lot at OW and I'm sure it's pretty widespread out there (and
even when we didn't use HS but Solr, we needed an equivalent feature).
Using range queries is a solution but it's a bit cumbersome for such a
common requirement.

Please note that Hibernate Search queries are now built using a wrapper in
OWSI-Core
<https://github.com/openwide-java/owsi-core-parent/blob/bd6ab1ec1d54c22ed3b2f8f94362b43223b01342/owsi-core/owsi-core-components/owsi-core-component-jpa-more/src/main/java/fr/openwide/core/jpa/more/business/search/query/HibernateSearchLuceneQueryFactoryImpl.java>
in
most recent applications, and it could easily be adapted to add a Date
match method (using method overloading). In fact, if I remember correctly I
had to do exactly that for one application.

One thing to note about the OW use case, too: I've never seen anything
other than a Date being used in business models of single-timezone
applications at Open Wide. See below why it's relevant.

> I think this new behavior would fix most of the issues you mention.

An easier implementation would be what you did with Elasticsearch using the
clone() method. But anyway, this would only fix the issue for Calendar. For
Date, we basically only have a GMT timestamp with no timezone data nor
field-based data, so there's really nothing we can do.
If we want to fix the default behavior for dates, the only solution I can
see is to use the default JVM timezone instead of GMT, maybe...

> And if you really need the behavior when dates in one time zone might be
a different date in a different time zone, then you definitely wouldn't use
the resolution option and stick to the full date with range queries.

All dates in one time zone may be a different date in a different time
zone... In fact, I'm pretty sure all dates in one time zone *are* a
different date in one different time zone. I see what you mean, but I just
wanted to point out how difficult it will be to explain properly in the
documentation. I don't know about you, but I really don't want to explain
in the docs that "this feature should only be used with java.util.Date if
your timezone is close to GMT", and I want even less to explain why...

Anyway, you do understand we're offering a feature that won't work properly
in most time zones, and will simply not work most of the time in time zones
such as, for instance, the one for the US west coast (UTC-8)? (in that
specific case it won't work after 4 PM).

Could we agree the current behavior should change, not only for
java.util.Calendar but also for java.util.Date?
If we do, we'll probably have to wait for 6.0, because users will have to
perform a full reindex after upgrading to a version of Hibernate Search
with the fix, even if they previously weren't affected by the bug.

Also:

> At the very least, I'd like us to agree that in the future, we will only
implement automatic truncation with date/time types where the timezone is
either irrelevant or included (for instance ZonedDateTime or LocalDate or
LocalTime, but *not* Instant).

Do you agree with the statement above?


> I would pay to see your face while reading this email :).

Yeah, well, not much surprise here :)

Yoann Rodière <yoann at hibernate.org>
Hibernate NoORM Team

On 9 January 2017 at 12:53, Guillaume Smet <guillaume.smet at gmail.com> wrote:

> Hi,
>
> On Thu, Jan 5, 2017 at 5:20 PM, Yoann Rodiere <yoann at hibernate.org> wrote:
>
>> That's a catchy subject, now I'm sure I got Guillaume's (angry) attention
>> :)
>>
>> Sanne wanted us to think about feature removal... Here's a proposal.
>>
>> The feature I'd like to deprecate/remove: automatic truncation of
>> date/calendars to a given resolution. It's used like that:
>>
>
> Yeah, as you can imagine, I'm pretty reluctant to the idea of removing
> this feature. We used it a lot at OW and I'm sure it's pretty widespread
> out there (and even when we didn't use HS but Solr, we needed an equivalent
> feature). Using range queries is a solution but it's a bit cumbersome for
> such a common requirement.
>
> I agree the current behavior might lead to unexpected results. To be
> honest, I think we should simply ignore the timezone when truncating. I
> mean, when I want to index at a day resolution, I want to index the user
> facing day, not the one in the server time zone or in GMT.
>
> So for instance, for 2016-01-01T00:00:00+01:00, I would index 2016-01-01,
> not 2015-12-31.
>
> So, as long as the resolution is less precise than day included, what I
> would do is in fact remove our call to DateTools.round and have something
> like:
> - create a GMT GregorianCalendar
> - don't set the calendar value using the time in millis but with the
> original fields from the calendar passed in parameter (or 0/1 depending on
> the resolution)
> - index this value
>
> I think this new behavior would fix most of the issues you mention. And if
> you really need the behavior when dates in one time zone might be a
> different date in a different time zone, then you definitely wouldn't use
> the resolution option and stick to the full date with range queries.
>
> So I agree the current behavior is probably not what user expects but I
> think it has value.
>
> I would pay to see your face while reading this email :).
>
> --
> Guillaume
>