[Pulp-dev] the "relative path" problem

[Daniel Alley]

Bump, this item needs to move forwards soon.  Does anyone have any thoughts?

On Wed, Apr 1, 2020 at 9:40 AM Pavel Picka <ppicka at redhat.com> wrote:

> Hi,
> I'd like to add one more question to this topic. Do you think it is a
> blocker for PRs [0] & [1] as by testing [2] this features I haven't run
> into real world example where two really same name packages appears.
> I think this is a 'must have' feature but until we solve/decide it we can
> have two features working may with warning in docs for users that can
> happen in some 'special' repositories.
>
> To follow topic directly I like proposed move to 'RepositoryContent' and
> add it to its uniqueness constraint (if I understand well).
>
> [0] https://github.com/pulp/pulp_rpm/pull/1657
> [1] https://github.com/pulp/pulp_rpm/pull/1642
> [2] tested with centos 7, 8, opensuse and SLE repositories
>
> On Wed, Apr 1, 2020 at 3:22 PM Daniel Alley <dalley at redhat.com> wrote:
>
>> We'd like to start a discussion on the "relative path problem" identified
>> recently.
>> Problem:
>>
>> Currently, a relative_path is tied to content in Pulp. This means that if
>> a content unit exists in two places within a repository or across
>> repositories, it has to be stored as two separate content units. This
>> creates redundant data and potential confusion for users.
>>
>> As a specific example, we need to support mirroring content in pulp_rpm
>> <https://pulp.plan.io/issues/6353>. Currently, for each location at
>> which a single package is stored, we’ll need to create a content unit. We
>> could end up with several records representing a single package. Users may
>> be confused about why they see multiple records for a package and they may
>> have trouble for example deciding which content unit to copy.
>> Proposed Solution:
>>
>> Move “relative_path” from its current location on ContentArtifact, to
>> RepositoryContent. This will require a sizable data migration. It is
>> possibly the case that in rare cases, repository versions may change
>> slightly due to deduplication.
>>
>> A repository-version-wide uniqueness constraint will be present on
>> “relative_path”, independently of any other repository uniquness
>> constraints (repo_key_fields) defined by the plugin writer.
>>
>> Modify the Stages API so that the relative_path can be processed in the
>> correct location – instead of “DeclarativeArtifact” it will likely need to
>> go on “DeclarativeContent”
>>
>> Remove “location_href” from the RPM Package content model – it was never
>> a true part of the RPM (file) metadata, it is derived from the repository
>> metadata. So storing it as a part of the Content unit doesn’t entirely make
>> sense.
>> Alternatives
>>
>> In most cases, a content unit will have a single relative path for a
>> content unit. Creating a general solution to solve a one-off problem is
>> usually not a good idea. As an alternative, we could look at another
>> solution for mirroring content. One example might be to create a new object
>> (e.g. RpmRepoMirrorContentMapping) that maps content to specific paths
>> within a repo or repo version.
>> Questions
>>
>>    - How do we handle this in pulp_file? How are content units
>>    identified in pulp_file without relative_path?
>>       - Checksum?
>>       - How was this problem handled in Pulp 2?
>>
>>
>> Please weigh in if you have any input on potential problems with the
>> proposal, potential alternate solutions, or other insights or questions!
>> _______________________________________________
>> Pulp-dev mailing list
>> Pulp-dev at redhat.com
>> https://www.redhat.com/mailman/listinfo/pulp-dev
>>
>
>
> --
> Pavel Picka
> Red Hat
>
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