Thanks Jane for starting the discussion.
Regarding #1, I also prefer `USE MODULES` syntax. It can be interpreted as
"setting the current order of modules", which is similar to "setting the
current catalog" for `USE CATALOG`.
Regarding #3, I'm fine to map modules purely by name because I think it
satisfies all the use cases we have at hand. But I guess we need to make
sure we're backward compatible, i.e. users don't need to change their yaml
files to configure the modules.
On Mon, Feb 1, 2021 at 3:10 PM Jark Wu <imj...@gmail.com> wrote:
> Thanks Jane for the summary and starting the discussion in the mailing
> list.
>
> Here are my thoughts:
>
> 1) syntax to reorder modules
> I agree with Rui Li it would be quite useful if we can have some syntax to
> reorder modules.
> I slightly prefer `USE MODULES x, y, z` than `RELOAD MODULES x, y, z`,
> because USE has a more sense of effective and specifying ordering, than
> RELOAD.
> From my feeling, RELOAD just means we unregister and register x,y,z modules
> again,
> it sounds like other registered modules are still in use and in the order.
>
> 3) mapping modules purely by name
> This can definitely improve the usability of loading modules, because
> the 'type=' property
> looks really redundant. We can think of this as a syntax sugar that the
> default type value is the module name.
> And we can support to specify 'type=' property in the future to allow
> multiple modules for one module type.
>
> Besides, I would like to mention one more change, that the module name
> proposed in FLIP-68 is a string literal.
> But I think we are all on the same page to change it into a simple
> (non-compound) identifier.
>
> LOAD/UNLOAD MODULE 'core'
> ==>
> LOAD/UNLOAD MODULE core
>
>
> Best,
> Jark
>
>
> On Sat, 30 Jan 2021 at 04:00, Jane Chan <qingyue....@gmail.com> wrote:
>
> > Hi everyone,
> >
> > I would like to start a discussion on FLINK-21045 [1] about supporting
> > `LOAD MODULE` and `UNLOAD MODULE` SQL syntax. It's first proposed by
> > FLIP-68 [2] as following.
> >
> > -- load a module with the given name and append it to the end of the
> module
> > list
> > LOAD MODULE 'name' [WITH ('type'='xxx', 'prop'='myProp', ...)]
> >
> > --unload a module by name from the module list and other modules remain
> in
> > the same relative positions
> > UNLOAD MODULE 'name'
> >
> > After a round of discussion on the Jira ticket, it seems some unanswered
> > questions need more opinions and suggestions.
> >
> > 1. The way to redefine resolution order easily
> >
> > Rui Li suggested introducing `USE MODULES` and adding similar
> > functionality to the API because
> >
> > > 1) It's very tedious to unload old modules just to reorder them.
> >
> > 2) Users may not even know how to "re-load" an old module if it was not
> > > initially loaded by the user, e.g. don't know which type to use.
> >
> >
> > Jane Chan wondered that module is not like the catalog which has a
> > concept of namespace could specify, and `USE` sounds like a
> > mutual-exclusive concept.
> > Maybe `RELOAD MODULES` can express upgrading the priority of the
> loaded
> > module(s).
> >
> >
> > 2. `LOAD/UNLOAD MODULE` v.s. `CREATE/DROP MODULE` syntax
> > Jark Wu and Nicholas Jiang proposed to use `CREATE/DROP MODULE`
> instead
> > of `LOAD/UNLOAD MODULE` because
> >
> > > 1) From a pure SQL user's perspective, maybe `CREATE MODULE + USE
> > MODULE`
> > > is easier to use rather than `LOAD/UNLOAD`.
> > > 2) This will be very similar to what the catalog used now.
> >
> >
> > Timo Walther would rather stick to the agreed design because
> > loading/unloading modules is a concept known from kernels etc.
> >
> > 3. Simplify the module design by mapping modules purely by name
> >
> > LOAD MODULE geo_utils
> > LOAD MODULE hive WITH ('version'='2.1') -- no dedicated
> 'type='/'module='
> > but allow only 1 module to be loaded parameterized
> > UNLOAD hive
> > USE MODULES hive, core
> >
> >
> > Please find more details in the reference link. Looking forward to your
> > feedback.
> >
> > [1] https://issues.apache.org/jira/browse/FLINK-21045#
> > <
> >
> https://cwiki.apache.org/confluence/display/FLINK/FLIP-68%3A+Extend+Core+Table+System+with+Pluggable+Modules
> > >
> > [2]
> >
> >
> https://cwiki.apache.org/confluence/display/FLINK/FLIP-68%3A+Extend+Core+Table+System+with+Pluggable+Modules
> >
> > Best,
> > Jane
> >
>
--
Best regards!
Rui Li
