Hi,

I thought about it a bit more and think that there is some good value in my
last proposal.

A lot of complexity comes from the fact that we want to allow overriding
built-in functions which are differently addressed as other functions (and
db objects).
We could just have "CREATE TEMPORARY FUNCTION" do exactly the same thing as
"CREATE FUNCTION" and treat both functions exactly the same except that:
1) temp functions disappear at the end of the session
2) temp function are resolved before other functions

This would be Dawid's proposal from the beginning of this thread (in case
you still remember... ;-) )

Temporarily overriding built-in functions would be supported with an
explicit command like

ALTER BUILTIN FUNCTION xxx TEMPORARILY AS ...

This would also address the concerns about accidentally changing the
semantics of built-in functions.
IMO, it can't get much more explicit than the above command.

Sorry for bringing up a new option in the middle of the discussion, but as
I said, I think it has a bunch of benefits and I don't see major drawbacks
(maybe you do?).

What do you think?

Fabian

Am Do., 19. Sept. 2019 um 11:24 Uhr schrieb Fabian Hueske <fhue...@gmail.com
>:

> Hi everyone,
>
> I thought again about option #1 and something that I don't like is that
> the resolved address of xyz is different in "CREATE FUNCTION xyz" and
> "CREATE TEMPORARY FUNCTION xyz".
> IMO, adding the keyword "TEMPORARY" should only change the lifecycle of
> the function, but not where it is located. This implicitly changed location
> might be confusing for users.
> After all, a temp function should behave pretty much like any other
> function, except for the fact that it disappears when the session is closed.
>
> Approach #2 with the additional keyword would make that pretty clear, IMO.
> However, I neither like GLOBAL (for reasons mentioned by Dawid) or BUILDIN
> (we are not adding a built-in function).
> So I'd be OK with #2 if we find a good keyword. In fact, approach #2 could
> also be an alias for approach #3 to avoid explicit specification of the
> system catalog/db.
>
> Approach #3 would be consistent with other db objects and the "CREATE
> FUNCTION" statement.
> Adding system catalog/db seems rather complex, but then again how often do
> we expect users to override built-in functions? If this becomes a major
> issue, we can still add option #2 as an alias.
>
> Not sure what's the best approach from an internal point of view, but I
> certainly think that consistent behavior is important.
> Hence my votes are:
>
> -1 for #1
> 0 for #2
> 0 for #3
>
> Btw. Did we consider a completely separate command for overriding built-in
> functions like "ALTER BUILTIN FUNCTION xxx TEMPORARILY AS ..."?
>
> Cheers, Fabian
>
>
> Am Do., 19. Sept. 2019 um 11:03 Uhr schrieb JingsongLee
> <lzljs3620...@aliyun.com.invalid>:
>
>> I know Hive and Spark can shadow built-in functions by temporary function.
>> Mysql, Oracle, Sql server can not shadow.
>> User can use full names to access functions instead of shadowing.
>>
>> So I think it is a completely new thing, and the direct way to deal with
>> new things is to add new grammar. So,
>> +1 for #2, +0 for #3, -1 for #1
>>
>> Best,
>> Jingsong Lee
>>
>>
>> ------------------------------------------------------------------
>> From:Kurt Young <ykt...@gmail.com>
>> Send Time:2019年9月19日(星期四) 16:43
>> To:dev <dev@flink.apache.org>
>> Subject:Re: [DISCUSS] FLIP-57 - Rework FunctionCatalog
>>
>> And let me make my vote complete:
>>
>> -1 for #1
>> +1 for #2 with different keyword
>> -0 for #3
>>
>> Best,
>> Kurt
>>
>>
>> On Thu, Sep 19, 2019 at 4:40 PM Kurt Young <ykt...@gmail.com> wrote:
>>
>> > Looks like I'm the only person who is willing to +1 to #2 for now :-)
>> > But I would suggest to change the keyword from GLOBAL to
>> > something like BUILTIN.
>> >
>> > I think #2 and #3 are almost the same proposal, just with different
>> > format to indicate whether it want to override built-in functions.
>> >
>> > My biggest reason to choose it is I want this behavior be consistent
>> > with temporal tables. I will give some examples to show the behavior
>> > and also make sure I'm not misunderstanding anything here.
>> >
>> > For most DBs, when user create a temporary table with:
>> >
>> > CREATE TEMPORARY TABLE t1
>> >
>> > It's actually equivalent with:
>> >
>> > CREATE TEMPORARY TABLE `curent_db`.t1
>> >
>> > If user change current database, they will not be able to access t1
>> without
>> > fully qualified name, .i.e db1.t1 (assuming db1 is current database when
>> > this temporary table is created).
>> >
>> > Only #2 and #3 followed this behavior and I would vote for this since
>> this
>> > makes such behavior consistent through temporal tables and functions.
>> >
>> > Why I'm not voting for #3 is a special catalog and database just looks
>> very
>> > hacky to me. It gave a imply that our built-in functions saved at a
>> > special
>> > catalog and database, which is actually not. Introducing a dedicated
>> > keyword
>> > like CREATE TEMPORARY BUILTIN FUNCTION looks more clear and
>> > straightforward. One can argue that we should avoid introducing new
>> > keyword,
>> > but it's also very rare that a system can overwrite built-in functions.
>> > Since we
>> > decided to support this, introduce a new keyword is not a big deal IMO.
>> >
>> > Best,
>> > Kurt
>> >
>> >
>> > On Thu, Sep 19, 2019 at 3:07 PM Piotr Nowojski <pi...@ververica.com>
>> > wrote:
>> >
>> >> Hi,
>> >>
>> >> It is a quite long discussion to follow and I hope I didn’t
>> misunderstand
>> >> anything. From the proposals presented by Xuefu I would vote:
>> >>
>> >> -1 for #1 and #2
>> >> +1 for #3
>> >>
>> >> Besides #3 being IMO more general and more consistent, having qualified
>> >> names (#3) would help/make easier for someone to use cross
>> >> databases/catalogs queries (joining multiple data sets/streams). For
>> >> example with some functions to manipulate/clean up/convert the stored
>> data
>> >> in different catalogs registered in the respective catalogs.
>> >>
>> >> Piotrek
>> >>
>> >> > On 19 Sep 2019, at 06:35, Jark Wu <imj...@gmail.com> wrote:
>> >> >
>> >> > I agree with Xuefu that inconsistent handling with all the other
>> >> objects is
>> >> > not a big problem.
>> >> >
>> >> > Regarding to option#3, the special "system.system" namespace may
>> confuse
>> >> > users.
>> >> > Users need to know the set of built-in function names to know when to
>> >> use
>> >> > "system.system" namespace.
>> >> > What will happen if user registers a non-builtin function name under
>> the
>> >> > "system.system" namespace?
>> >> > Besides, I think it doesn't solve the "explode" problem I mentioned
>> at
>> >> the
>> >> > beginning of this thread.
>> >> >
>> >> > So here is my vote:
>> >> >
>> >> > +1 for #1
>> >> > 0 for #2
>> >> > -1 for #3
>> >> >
>> >> > Best,
>> >> > Jark
>> >> >
>> >> >
>> >> > On Thu, 19 Sep 2019 at 08:38, Xuefu Z <usxu...@gmail.com> wrote:
>> >> >
>> >> >> @Dawid, Re: we also don't need additional referencing the
>> >> specialcatalog
>> >> >> anywhere.
>> >> >>
>> >> >> True. But once we allow such reference, then user can do so in any
>> >> possible
>> >> >> place where a function name is expected, for which we have to
>> handle.
>> >> >> That's a big difference, I think.
>> >> >>
>> >> >> Thanks,
>> >> >> Xuefu
>> >> >>
>> >> >> On Wed, Sep 18, 2019 at 5:25 PM Dawid Wysakowicz <
>> >> >> wysakowicz.da...@gmail.com>
>> >> >> wrote:
>> >> >>
>> >> >>> @Bowen I am not suggesting introducing additional catalog. I think
>> we
>> >> >> need
>> >> >>> to get rid of the current built-in catalog.
>> >> >>>
>> >> >>> @Xuefu in option #3 we also don't need additional referencing the
>> >> special
>> >> >>> catalog anywhere else besides in the CREATE statement. The
>> resolution
>> >> >>> behaviour is exactly the same in both options.
>> >> >>>
>> >> >>> On Thu, 19 Sep 2019, 08:17 Xuefu Z, <usxu...@gmail.com> wrote:
>> >> >>>
>> >> >>>> Hi Dawid,
>> >> >>>>
>> >> >>>> "GLOBAL" is a temporary keyword that was given to the approach. It
>> >> can
>> >> >> be
>> >> >>>> changed to something else for better.
>> >> >>>>
>> >> >>>> The difference between this and the #3 approach is that we only
>> need
>> >> >> the
>> >> >>>> keyword for this create DDL. For other places (such as function
>> >> >>>> referencing), no keyword or special namespace is needed.
>> >> >>>>
>> >> >>>> Thanks,
>> >> >>>> Xuefu
>> >> >>>>
>> >> >>>> On Wed, Sep 18, 2019 at 4:32 PM Dawid Wysakowicz <
>> >> >>>> wysakowicz.da...@gmail.com>
>> >> >>>> wrote:
>> >> >>>>
>> >> >>>>> Hi,
>> >> >>>>> I think it makes sense to start voting at this point.
>> >> >>>>>
>> >> >>>>> Option 1: Only 1-part identifiers
>> >> >>>>> PROS:
>> >> >>>>> - allows shadowing built-in functions
>> >> >>>>> CONS:
>> >> >>>>> - incosistent with all the other objects, both permanent &
>> temporary
>> >> >>>>> - does not allow shadowing catalog functions
>> >> >>>>>
>> >> >>>>> Option 2: Special keyword for built-in function
>> >> >>>>> I think this is quite similar to the special catalog/db. The
>> thing I
>> >> >> am
>> >> >>>>> strongly against in this proposal is the GLOBAL keyword. This
>> >> keyword
>> >> >>>> has a
>> >> >>>>> meaning in rdbms systems and means a function that is present
>> for a
>> >> >>>>> lifetime of a session in which it was created, but available in
>> all
>> >> >>> other
>> >> >>>>> sessions. Therefore I really don't want to use this keyword in a
>> >> >>>> different
>> >> >>>>> context.
>> >> >>>>>
>> >> >>>>> Option 3: Special catalog/db
>> >> >>>>>
>> >> >>>>> PROS:
>> >> >>>>> - allows shadowing built-in functions
>> >> >>>>> - allows shadowing catalog functions
>> >> >>>>> - consistent with other objects
>> >> >>>>> CONS:
>> >> >>>>> - we introduce a special namespace for built-in functions
>> >> >>>>>
>> >> >>>>> I don't see a problem with introducing the special namespace. In
>> the
>> >> >>> end
>> >> >>>> it
>> >> >>>>> is very similar to the keyword approach. In this case the
>> catalog/db
>> >> >>>>> combination would be the "keyword"
>> >> >>>>>
>> >> >>>>> Therefore my votes:
>> >> >>>>> Option 1: -0
>> >> >>>>> Option 2: -1 (I might change to +0 if we can come up with a
>> better
>> >> >>>> keyword)
>> >> >>>>> Option 3: +1
>> >> >>>>>
>> >> >>>>> Best,
>> >> >>>>> Dawid
>> >> >>>>>
>> >> >>>>>
>> >> >>>>> On Thu, 19 Sep 2019, 05:12 Xuefu Z, <usxu...@gmail.com> wrote:
>> >> >>>>>
>> >> >>>>>> Hi Aljoscha,
>> >> >>>>>>
>> >> >>>>>> Thanks for the summary and these are great questions to be
>> >> >> answered.
>> >> >>>> The
>> >> >>>>>> answer to your first question is clear: there is a general
>> >> >> agreement
>> >> >>> to
>> >> >>>>>> override built-in functions with temp functions.
>> >> >>>>>>
>> >> >>>>>> However, your second and third questions are sort of related,
>> as a
>> >> >>>>> function
>> >> >>>>>> reference can be either just function name (like "func") or in
>> the
>> >> >>> form
>> >> >>>>> or
>> >> >>>>>> "cat.db.func". When a reference is just function name, it can
>> mean
>> >> >>>>> either a
>> >> >>>>>> built-in function or a function defined in the current cat/db.
>> If
>> >> >> we
>> >> >>>>>> support overriding a built-in function with a temp function,
>> such
>> >> >>>>>> overriding can also cover a function in the current cat/db.
>> >> >>>>>>
>> >> >>>>>> I think what Timo referred as "overriding a catalog function"
>> >> >> means a
>> >> >>>>> temp
>> >> >>>>>> function defined as "cat.db.func" overrides a catalog function
>> >> >> "func"
>> >> >>>> in
>> >> >>>>>> cat/db even if cat/db is not current. To support this, temp
>> >> >> function
>> >> >>>> has
>> >> >>>>> to
>> >> >>>>>> be tied to a cat/db. What's why I said above that the 2nd and
>> 3rd
>> >> >>>>> questions
>> >> >>>>>> are related. The problem with such support is the ambiguity when
>> >> >> user
>> >> >>>>>> defines a function w/o namespace, "CREATE TEMPORARY FUNCTION
>> func
>> >> >>> ...".
>> >> >>>>>> Here "func" can means a global temp function, or a temp
>> function in
>> >> >>>>> current
>> >> >>>>>> cat/db. If we can assume the former, this creates an
>> inconsistency
>> >> >>>>> because
>> >> >>>>>> "CREATE FUNCTION func" actually means a function in current
>> cat/db.
>> >> >>> If
>> >> >>>> we
>> >> >>>>>> assume the latter, then there is no way for user to create a
>> global
>> >> >>>> temp
>> >> >>>>>> function.
>> >> >>>>>>
>> >> >>>>>> Giving a special namespace for built-in functions may solve the
>> >> >>>> ambiguity
>> >> >>>>>> problem above, but it also introduces artificial
>> catalog/database
>> >> >>> that
>> >> >>>>>> needs special treatment and pollutes the cleanness of  the
>> code. I
>> >> >>>> would
>> >> >>>>>> rather introduce a syntax in DDL to solve the problem, like
>> "CREATE
>> >> >>>>>> [GLOBAL] TEMPORARY FUNCTION func".
>> >> >>>>>>
>> >> >>>>>> Thus, I'd like to summarize a few candidate proposals for voting
>> >> >>>>> purposes:
>> >> >>>>>>
>> >> >>>>>> 1. Support only global, temporary functions without namespace.
>> Such
>> >> >>>> temp
>> >> >>>>>> functions overrides built-in functions and catalog functions in
>> >> >>> current
>> >> >>>>>> cat/db. The resolution order is: temp functions -> built-in
>> >> >> functions
>> >> >>>> ->
>> >> >>>>>> catalog functions. (Partially or fully qualified functions has
>> no
>> >> >>>>>> ambiguity!)
>> >> >>>>>>
>> >> >>>>>> 2. In addition to #1, support creating and referencing temporary
>> >> >>>>> functions
>> >> >>>>>> associated with a cat/db with "GLOBAL" qualifier in DDL for
>> global
>> >> >>> temp
>> >> >>>>>> functions. The resolution order is: global temp functions ->
>> >> >> built-in
>> >> >>>>>> functions -> temp functions in current cat/db -> catalog
>> function.
>> >> >>>>>> (Resolution for partially or fully qualified function reference
>> is:
>> >> >>>> temp
>> >> >>>>>> functions -> persistent functions.)
>> >> >>>>>>
>> >> >>>>>> 3. In addition to #1, support creating and referencing temporary
>> >> >>>>> functions
>> >> >>>>>> associated with a cat/db with a special namespace for built-in
>> >> >>>> functions
>> >> >>>>>> and global temp functions. The resolution is the same as #2,
>> except
>> >> >>>> that
>> >> >>>>>> the special namespace might be prefixed to a reference to a
>> >> >> built-in
>> >> >>>>>> function or global temp function. (In absence of the special
>> >> >>> namespace,
>> >> >>>>> the
>> >> >>>>>> resolution order is the same as in #2.)
>> >> >>>>>>
>> >> >>>>>> My personal preference is #1, given the unknown use case and
>> >> >>> introduced
>> >> >>>>>> complexity for #2 and #3. However, #2 is an acceptable
>> alternative.
>> >> >>>> Thus,
>> >> >>>>>> my votes are:
>> >> >>>>>>
>> >> >>>>>> +1 for #1
>> >> >>>>>> +0 for #2
>> >> >>>>>> -1 for #3
>> >> >>>>>>
>> >> >>>>>> Everyone, please cast your vote (in above format please!), or
>> let
>> >> >> me
>> >> >>>> know
>> >> >>>>>> if you have more questions or other candidates.
>> >> >>>>>>
>> >> >>>>>> Thanks,
>> >> >>>>>> Xuefu
>> >> >>>>>>
>> >> >>>>>>
>> >> >>>>>>
>> >> >>>>>>
>> >> >>>>>>
>> >> >>>>>>
>> >> >>>>>>
>> >> >>>>>> On Wed, Sep 18, 2019 at 6:42 AM Aljoscha Krettek <
>> >> >>> aljos...@apache.org>
>> >> >>>>>> wrote:
>> >> >>>>>>
>> >> >>>>>>> Hi,
>> >> >>>>>>>
>> >> >>>>>>> I think this discussion and the one for FLIP-64 are very
>> >> >> connected.
>> >> >>>> To
>> >> >>>>>>> resolve the differences, think we have to think about the basic
>> >> >>>>>> principles
>> >> >>>>>>> and find consensus there. The basic questions I see are:
>> >> >>>>>>>
>> >> >>>>>>> - Do we want to support overriding builtin functions?
>> >> >>>>>>> - Do we want to support overriding catalog functions?
>> >> >>>>>>> - And then later: should temporary functions be tied to a
>> >> >>>>>>> catalog/database?
>> >> >>>>>>>
>> >> >>>>>>> I don’t have much to say about these, except that we should
>> >> >>> somewhat
>> >> >>>>>> stick
>> >> >>>>>>> to what the industry does. But I also understand that the
>> >> >> industry
>> >> >>> is
>> >> >>>>>>> already very divided on this.
>> >> >>>>>>>
>> >> >>>>>>> Best,
>> >> >>>>>>> Aljoscha
>> >> >>>>>>>
>> >> >>>>>>>> On 18. Sep 2019, at 11:41, Jark Wu <imj...@gmail.com> wrote:
>> >> >>>>>>>>
>> >> >>>>>>>> Hi,
>> >> >>>>>>>>
>> >> >>>>>>>> +1 to strive for reaching consensus on the remaining topics.
>> We
>> >> >>> are
>> >> >>>>>>> close to the truth. It will waste a lot of time if we resume
>> the
>> >> >>>> topic
>> >> >>>>>> some
>> >> >>>>>>> time later.
>> >> >>>>>>>>
>> >> >>>>>>>> +1 to “1-part/override” and I’m also fine with Timo’s
>> >> >>> “cat.db.fun”
>> >> >>>>> way
>> >> >>>>>>> to override a catalog function.
>> >> >>>>>>>>
>> >> >>>>>>>> I’m not sure about “system.system.fun”, it introduces a
>> >> >>> nonexistent
>> >> >>>>> cat
>> >> >>>>>>> & db? And we still need to do special treatment for the
>> dedicated
>> >> >>>>>>> system.system cat & db?
>> >> >>>>>>>>
>> >> >>>>>>>> Best,
>> >> >>>>>>>> Jark
>> >> >>>>>>>>
>> >> >>>>>>>>
>> >> >>>>>>>>> 在 2019年9月18日,06:54,Timo Walther <twal...@apache.org> 写道:
>> >> >>>>>>>>>
>> >> >>>>>>>>> Hi everyone,
>> >> >>>>>>>>>
>> >> >>>>>>>>> @Xuefu: I would like to avoid adding too many things
>> >> >>>> incrementally.
>> >> >>>>>>> Users should be able to override all catalog objects
>> consistently
>> >> >>>>>> according
>> >> >>>>>>> to FLIP-64 (Support for Temporary Objects in Table module). If
>> >> >>>>> functions
>> >> >>>>>>> are treated completely different, we need more code and special
>> >> >>>> cases.
>> >> >>>>>> From
>> >> >>>>>>> an implementation perspective, this topic only affects the
>> lookup
>> >> >>>> logic
>> >> >>>>>>> which is rather low implementation effort which is why I would
>> >> >> like
>> >> >>>> to
>> >> >>>>>>> clarify the remaining items. As you said, we have a slight
>> >> >> consenus
>> >> >>>> on
>> >> >>>>>>> overriding built-in functions; we should also strive for
>> reaching
>> >> >>>>>> consensus
>> >> >>>>>>> on the remaining topics.
>> >> >>>>>>>>>
>> >> >>>>>>>>> @Dawid: I like your idea as it ensures registering catalog
>> >> >>> objects
>> >> >>>>>>> consistent and the overriding of built-in functions more
>> >> >> explicit.
>> >> >>>>>>>>>
>> >> >>>>>>>>> Thanks,
>> >> >>>>>>>>> Timo
>> >> >>>>>>>>>
>> >> >>>>>>>>>
>> >> >>>>>>>>> On 17.09.19 11:59, kai wang wrote:
>> >> >>>>>>>>>> hi, everyone
>> >> >>>>>>>>>> I think this flip is very meaningful. it supports functions
>> >> >>> that
>> >> >>>>> can
>> >> >>>>>> be
>> >> >>>>>>>>>> shared by different catalogs and dbs, reducing the
>> >> >> duplication
>> >> >>> of
>> >> >>>>>>> functions.
>> >> >>>>>>>>>>
>> >> >>>>>>>>>> Our group based on flink's sql parser module implements
>> >> >> create
>> >> >>>>>> function
>> >> >>>>>>>>>> feature, stores the parsed function metadata and schema into
>> >> >>>> mysql,
>> >> >>>>>> and
>> >> >>>>>>>>>> also customizes the catalog, customizes sql-client to
>> support
>> >> >>>>> custom
>> >> >>>>>>>>>> schemas and functions. Loaded, but the function is currently
>> >> >>>>> global,
>> >> >>>>>>> and is
>> >> >>>>>>>>>> not subdivided according to catalog and db.
>> >> >>>>>>>>>>
>> >> >>>>>>>>>> In addition, I very much hope to participate in the
>> >> >> development
>> >> >>>> of
>> >> >>>>>> this
>> >> >>>>>>>>>> flip, I have been paying attention to the community, but
>> >> >> found
>> >> >>> it
>> >> >>>>> is
>> >> >>>>>>> more
>> >> >>>>>>>>>> difficult to join.
>> >> >>>>>>>>>> thank you.
>> >> >>>>>>>>>>
>> >> >>>>>>>>>> Xuefu Z <usxu...@gmail.com> 于2019年9月17日周二 上午11:19写道:
>> >> >>>>>>>>>>
>> >> >>>>>>>>>>> Thanks to Tmo and Dawid for sharing thoughts.
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> It seems to me that there is a general consensus on having
>> >> >>> temp
>> >> >>>>>>> functions
>> >> >>>>>>>>>>> that have no namespaces and overwrite built-in functions.
>> >> >> (As
>> >> >>> a
>> >> >>>>> side
>> >> >>>>>>> note
>> >> >>>>>>>>>>> for comparability, the current user defined functions are
>> >> >> all
>> >> >>>>>>> temporary and
>> >> >>>>>>>>>>> having no namespaces.)
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> Nevertheless, I can also see the merit of having namespaced
>> >> >>> temp
>> >> >>>>>>> functions
>> >> >>>>>>>>>>> that can overwrite functions defined in a specific cat/db.
>> >> >>>>> However,
>> >> >>>>>>> this
>> >> >>>>>>>>>>> idea appears orthogonal to the former and can be added
>> >> >>>>>> incrementally.
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> How about we first implement non-namespaced temp functions
>> >> >> now
>> >> >>>> and
>> >> >>>>>>> leave
>> >> >>>>>>>>>>> the door open for namespaced ones for later releases as the
>> >> >>>>>>> requirement
>> >> >>>>>>>>>>> might become more crystal? This also helps shorten the
>> >> >> debate
>> >> >>>> and
>> >> >>>>>>> allow us
>> >> >>>>>>>>>>> to make some progress along this direction.
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> As to Dawid's idea of having a dedicated cat/db to host the
>> >> >>>>>> temporary
>> >> >>>>>>> temp
>> >> >>>>>>>>>>> functions that don't have namespaces, my only concern is
>> the
>> >> >>>>> special
>> >> >>>>>>>>>>> treatment for a cat/db, which makes code less clean, as
>> >> >>> evident
>> >> >>>> in
>> >> >>>>>>> treating
>> >> >>>>>>>>>>> the built-in catalog currently.
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> Thanks,
>> >> >>>>>>>>>>> Xuefiu
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> On Mon, Sep 16, 2019 at 5:07 PM Dawid Wysakowicz <
>> >> >>>>>>>>>>> wysakowicz.da...@gmail.com>
>> >> >>>>>>>>>>> wrote:
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>>> Hi,
>> >> >>>>>>>>>>>> Another idea to consider on top of Timo's suggestion. How
>> >> >>> about
>> >> >>>>> we
>> >> >>>>>>> have a
>> >> >>>>>>>>>>>> special namespace (catalog + database) for built-in
>> >> >> objects?
>> >> >>>> This
>> >> >>>>>>> catalog
>> >> >>>>>>>>>>>> would be invisible for users as Xuefu was suggesting.
>> >> >>>>>>>>>>>>
>> >> >>>>>>>>>>>> Then users could still override built-in functions, if
>> they
>> >> >>>> fully
>> >> >>>>>>> qualify
>> >> >>>>>>>>>>>> object with the built-in namespace, but by default the
>> >> >> common
>> >> >>>>> logic
>> >> >>>>>>> of
>> >> >>>>>>>>>>>> current dB & cat would be used.
>> >> >>>>>>>>>>>>
>> >> >>>>>>>>>>>> CREATE TEMPORARY FUNCTION func ...
>> >> >>>>>>>>>>>> registers temporary function in current cat & dB
>> >> >>>>>>>>>>>>
>> >> >>>>>>>>>>>> CREATE TEMPORARY FUNCTION cat.db.func ...
>> >> >>>>>>>>>>>> registers temporary function in cat db
>> >> >>>>>>>>>>>>
>> >> >>>>>>>>>>>> CREATE TEMPORARY FUNCTION system.system.func ...
>> >> >>>>>>>>>>>> Overrides built-in function with temporary function
>> >> >>>>>>>>>>>>
>> >> >>>>>>>>>>>> The built-in/system namespace would not be writable for
>> >> >>>> permanent
>> >> >>>>>>>>>>> objects.
>> >> >>>>>>>>>>>> WDYT?
>> >> >>>>>>>>>>>>
>> >> >>>>>>>>>>>> This way I think we can have benefits of both solutions.
>> >> >>>>>>>>>>>>
>> >> >>>>>>>>>>>> Best,
>> >> >>>>>>>>>>>> Dawid
>> >> >>>>>>>>>>>>
>> >> >>>>>>>>>>>>
>> >> >>>>>>>>>>>> On Tue, 17 Sep 2019, 07:24 Timo Walther, <
>> >> >> twal...@apache.org
>> >> >>>>
>> >> >>>>>> wrote:
>> >> >>>>>>>>>>>>
>> >> >>>>>>>>>>>>> Hi Bowen,
>> >> >>>>>>>>>>>>>
>> >> >>>>>>>>>>>>> I understand the potential benefit of overriding certain
>> >> >>>>> built-in
>> >> >>>>>>>>>>>>> functions. I'm open to such a feature if many people
>> >> >> agree.
>> >> >>>>>>> However, it
>> >> >>>>>>>>>>>>> would be great to still support overriding catalog
>> >> >> functions
>> >> >>>>> with
>> >> >>>>>>>>>>>>> temporary functions in order to prototype a query even
>> >> >>> though
>> >> >>>> a
>> >> >>>>>>>>>>>>> catalog/database might not be available currently or
>> >> >> should
>> >> >>>> not
>> >> >>>>> be
>> >> >>>>>>>>>>>>> modified yet. How about we support both cases?
>> >> >>>>>>>>>>>>>
>> >> >>>>>>>>>>>>> CREATE TEMPORARY FUNCTION abs
>> >> >>>>>>>>>>>>> -> creates/overrides a built-in function and never
>> >> >>> consideres
>> >> >>>>>>> current
>> >> >>>>>>>>>>>>> catalog and database; inconsistent with other DDL but
>> >> >>>> acceptable
>> >> >>>>>> for
>> >> >>>>>>>>>>>>> functions I guess.
>> >> >>>>>>>>>>>>> CREATE TEMPORARY FUNCTION cat.db.fun
>> >> >>>>>>>>>>>>> -> creates/overrides a catalog function
>> >> >>>>>>>>>>>>>
>> >> >>>>>>>>>>>>> Regarding "Flink don't have any other built-in objects
>> >> >>>> (tables,
>> >> >>>>>>> views)
>> >> >>>>>>>>>>>>> except functions", this might change in the near future.
>> >> >>> Take
>> >> >>>>>>>>>>>>> https://issues.apache.org/jira/browse/FLINK-13900 as an
>> >> >>>>> example.
>> >> >>>>>>>>>>>>>
>> >> >>>>>>>>>>>>> Thanks,
>> >> >>>>>>>>>>>>> Timo
>> >> >>>>>>>>>>>>>
>> >> >>>>>>>>>>>>> On 14.09.19 01:40, Bowen Li wrote:
>> >> >>>>>>>>>>>>>> Hi Fabian,
>> >> >>>>>>>>>>>>>>
>> >> >>>>>>>>>>>>>> Yes, I agree 1-part/no-override is the least favorable
>> >> >>> thus I
>> >> >>>>>>> didn't
>> >> >>>>>>>>>>>>>> include that as a voting option, and the discussion is
>> >> >>> mainly
>> >> >>>>>>> between
>> >> >>>>>>>>>>>>>> 1-part/override builtin and 3-part/not override builtin.
>> >> >>>>>>>>>>>>>>
>> >> >>>>>>>>>>>>>> Re > However, it means that temp functions are
>> >> >> differently
>> >> >>>>>> treated
>> >> >>>>>>>>>>> than
>> >> >>>>>>>>>>>>>> other db objects.
>> >> >>>>>>>>>>>>>> IMO, the treatment difference results from the fact that
>> >> >>>>>> functions
>> >> >>>>>>>>>>> are
>> >> >>>>>>>>>>>> a
>> >> >>>>>>>>>>>>>> bit different from other objects - Flink don't have any
>> >> >>> other
>> >> >>>>>>>>>>> built-in
>> >> >>>>>>>>>>>>>> objects (tables, views) except functions.
>> >> >>>>>>>>>>>>>>
>> >> >>>>>>>>>>>>>> Cheers,
>> >> >>>>>>>>>>>>>> Bowen
>> >> >>>>>>>>>>>>>>
>> >> >>>>>>>>>>>>>
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> --
>> >> >>>>>>>>>>> Xuefu Zhang
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>>> "In Honey We Trust!"
>> >> >>>>>>>>>>>
>> >> >>>>>>>>>
>> >> >>>>>>>>
>> >> >>>>>>>
>> >> >>>>>>>
>> >> >>>>>>
>> >> >>>>>> --
>> >> >>>>>> Xuefu Zhang
>> >> >>>>>>
>> >> >>>>>> "In Honey We Trust!"
>> >> >>>>>>
>> >> >>>>>
>> >> >>>>
>> >> >>>>
>> >> >>>> --
>> >> >>>> Xuefu Zhang
>> >> >>>>
>> >> >>>> "In Honey We Trust!"
>> >> >>>>
>> >> >>>
>> >> >>
>> >> >>
>> >> >> --
>> >> >> Xuefu Zhang
>> >> >>
>> >> >> "In Honey We Trust!"
>> >> >>
>> >>
>> >>
>>
>

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