---
id: pr-cccl-cub-8439
repo: NVIDIA/cccl
pr: 8439
title: Swap the `store_algorithm` and `scan_algorithm` in `scan_by_key_policy`
author: bernhardmgruber
date: '2026-04-15'
url: https://github.com/NVIDIA/cccl/pull/8439
source_category: upstream-code
architectures:
- sm100
tags:
- scan
techniques: []
hardware_features: []
kernel_types:
- scan
languages: []
captured_at: '2026-05-16'
status: merged
merge_sha: ebc3e8125953aaf27f5e86ef4411844082b3b8fa
inclusion_reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.
changed_paths:
- cub/benchmarks/bench/scan/exclusive/by_key.cu
- cub/cub/device/dispatch/tuning/tuning_scan_by_key.cuh
artifact_dir: evidence/pull-bundles/cccl-cub/gh-8439
head_ref_oid: 36912ec44ae16019e2d4a82f1fbf7909fb731efb
---
# Swap the `store_algorithm` and `scan_algorithm` in `scan_by_key_policy`

- Repository: `NVIDIA/cccl`
- PR: [8439](https://github.com/NVIDIA/cccl/pull/8439)
- Decision: `Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.`
- Reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.

## Changed Paths

- `cub/benchmarks/bench/scan/exclusive/by_key.cu`
- `cub/cub/device/dispatch/tuning/tuning_scan_by_key.cuh`

## Evidence Bundle

`evidence/pull-bundles/cccl-cub/gh-8439`
