I really like this proposal. I think it has narrowed down and solved the
essential problem of not shuffling excess redundant data, and also provides
the vast majority of the functionality that a lambda would, with
significantly better debugability and usability too, since the dynamic
destination pattern string can be in display data, etc.
Kenn
On Wed, Mar 27, 2024 at 1:58 PM Robert Bradshaw via dev <dev@beam.apache.org>
wrote:
> On Wed, Mar 27, 2024 at 10:20 AM Reuven Lax <re...@google.com> wrote:
>
>> Can the prefix still be generated programmatically at graph creation time?
>>
>
> Yes. It's just a property of the transform passed by the user at
> configuration time.
>
>
>> On Wed, Mar 27, 2024 at 9:40 AM Robert Bradshaw <rober...@google.com>
>> wrote:
>>
>>> On Wed, Mar 27, 2024 at 9:12 AM Reuven Lax <re...@google.com> wrote:
>>>
>>>> This does seem like the best compromise, though I think there will
>>>> still end up being performance issues. A common pattern I've seen is that
>>>> there is a long common prefix to the dynamic destination followed the
>>>> dynamic component. e.g. the destination might be
>>>> long/common/path/to/destination/files/<per-user-file>. In this case, the
>>>> prefix is often much larger than messages themselves and is what gets
>>>> effectively encoded in the lambda.
>>>>
>>>
>>> The idea here is that the destination would be given as a format string,
>>> say, "long/common/path/to/destination/files/{dest_info.user}". Another way
>>> to put this is that we support (only) "lambdas" that are represented as
>>> string substitutions. (The fact that dest_info does not have to be part of
>>> the record, and can be the output of an arbitrary map if need be, makes
>>> this restriction not so bad.)
>>>
>>> As well as solving the performance issues, I think this is actually a
>>> pretty convenient and natural way for the user to name their destination
>>> (for the common usecase, even easier than providing a lambda), and has the
>>> benefit of being much more transparent than an arbitrary callable as well
>>> for introspection (for both machine and human that may look at the
>>> resulting pipeline).
>>>
>>>
>>>> I'm not entirely sure how to address this in a portable context. We
>>>> might simply have to accept the extra overhead when going cross language.
>>>>
>>>> Reuven
>>>>
>>>> On Wed, Mar 27, 2024 at 8:51 AM Robert Bradshaw via dev <
>>>> dev@beam.apache.org> wrote:
>>>>
>>>>> Thanks for putting this together, it will be a really useful feature
>>>>> to have.
>>>>>
>>>>> I am in favor of the string-pattern approaches. I think we need to
>>>>> support both the {record=..., dest_info=...} and the elide-fields
>>>>> approaches, as the former is nicer when one has a fixed representation for
>>>>> the output record (e.g. a proto or avro schema) and the flattened form for
>>>>> ease of use in more free-form contexts (e.g. when producing records from
>>>>> YAML and SQL).
>>>>>
>>>>> Also left some comments on the doc.
>>>>>
>>>>>
>>>>> On Wed, Mar 27, 2024 at 6:51 AM Ahmed Abualsaud via dev <
>>>>> dev@beam.apache.org> wrote:
>>>>>
>>>>>> Hey all,
>>>>>>
>>>>>> There have been some conversations lately about how best to enable
>>>>>> dynamic destinations in a portable context. Usually, this comes up for
>>>>>> cross-language transforms and more recently for Beam YAML.
>>>>>>
>>>>>> I've started a short doc outlining some routes we could take. The
>>>>>> purpose is to establish a good standard for supporting dynamic
>>>>>> destinations
>>>>>> with portability, one that can be applied to most use cases and IOs.
>>>>>> Please
>>>>>> take a look and add any thoughts!
>>>>>>
>>>>>> https://s.apache.org/portable-dynamic-destinations
>>>>>>
>>>>>> Best,
>>>>>> Ahmed
>>>>>>
>>>>>
