fix: Prevent DISTINCT ON internal sorting from leaking past joins #5633
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Per the PRQL spec, `group` resets the order - any `sort` inside a group is for internal row selection (determining which row to keep), not output ordering. Previously, when using DISTINCT ON (Postgres), this internal sorting was incorrectly propagating to the outer query after a join. This fix tracks whether sorting originated from DISTINCT ON and clears it at join boundaries, while preserving explicit user-requested sorts that come after the group. Fixes PRQL#4633 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <[email protected]>
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Summary
Fixes #4633 - sort inside group should not leak to outer query after join.
Per the PRQL spec,
groupresets the order. When usinggroup (sort x | take 1), the sorting is for row selection (which row to keep per group), not output ordering. Previously, this internal DISTINCT ON sorting was incorrectly propagating to the outer query after a join.Changes:
Why DISTINCT ON specifically?
SqlTransform::Sortfollowed byDistinctOntake > 1or non-Postgres) embeds sorting in the window function, so it doesn't have this issueTest plan
task prqlc:pull-requestpasses🤖 Generated with Claude Code