Improve the performance of the latest publication lookup when serving content from a repository-backed distribution. - #8135
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Distribution.get_repository_publication_and_version() resolves the newest publication for a repository-backed distribution with repository_version__in=repository.versions.all(). Django renders that as a subquery joined on pulp_id, which hides repository_id from the planner. It cannot use the (repository_id, number) unique index and instead scans the global index on number, filtering each row by repository. Since number is a per-repository counter and that index is global, the work is set by the total number of repository versions across all repositories rather than by the size of the repository being served. On an installation with a large number of repository versions this scans a substantial portion of core_repositoryversion to return a single row, and every repository degrades as any of them grow. Filtering with repository_version__repository selects the same rows but keeps repository_id visible, so the planner uses the (repository_id, number) index and the lookup becomes a short index scan. The same query also pulled repository_version.content_ids in via select_related. Nothing on this path reads it, and it holds every content unit UUID in the version, so defer it. closes pulp#1995 Assisted-by: Claude Opus 5 (GitHub Copilot)
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Backport to 3.119: 💚 backport PR created✅ Backport PR branch: Backported as #8138 🤖 @patchback |
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Distribution.get_repository_publication_and_version() resolves the newest publication for a repository-backed distribution with repository_version__in=repository.versions.all(). Django renders that as a subquery joined on pulp_id, which hides repository_id from the planner. It cannot use the (repository_id, number) unique index and instead scans the global index on number, filtering each row by repository.
Since number is a per-repository counter and that index is global, the work is set by the total number of repository versions across all repositories rather than by the size of the repository being served. On an installation with a large number of repository versions this scans a substantial portion of core_repositoryversion to return a single row, and every repository degrades as any of them grow.
Filtering with repository_version__repository selects the same rows but keeps repository_id visible, so the planner uses the (repository_id, number) index and the lookup becomes a short index scan.
The same query was also hydrating
repository_version.content_idsthroughselect_related, which nothing on this path reads; it is now deferred.closes #1995
Assisted-by: Claude Opus 5 (GitHub Copilot)
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