Replace hash join internals with HashCSR - #23640
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rootjalex
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Aug 12, 2026
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| auto const rank = slot_count_ref.fetch_add(size_type{1}, cuda::memory_order_relaxed); | ||
| build_positions[index] = {slot, rank}; |
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This, storing rank AOT, is a nice optimization the original implementation did not have! :)
rootjalex
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Aug 12, 2026
| probe_slots[index] = found ? static_cast<size_type>(slot) : CUDF_SIZE_TYPE_SENTINEL; | ||
| } | ||
| if (match_counts != nullptr) { | ||
| match_counts[index] = IsOuter ? cuda::std::max(count, size_type{1}) : count; |
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I think this should be IsOuterOrLeft ?
rootjalex
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Aug 12, 2026
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| if (found && matched_slots != nullptr) { | ||
| auto matched_slot_ref = | ||
| cuda::atomic_ref<std::uint32_t, cuda::thread_scope_device>{matched_slots[slot]}; | ||
| auto expected = std::uint32_t{0}; | ||
| if (matched_slot_ref.compare_exchange_strong( | ||
| expected, std::uint32_t{1}, cuda::memory_order_relaxed)) { | ||
| cuda::atomic_ref<unsigned long long, cuda::thread_scope_device>{*matched_build_rows} | ||
| .fetch_add(static_cast<unsigned long long>(count), cuda::memory_order_relaxed); | ||
| } | ||
| } |
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I'm a bit confused by this. Some comments could help with it. Is this implementing the right/outer join matching array we discussed?
rootjalex
reviewed
Aug 12, 2026
| } | ||
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| template <bool IsOuter> | ||
| CUDF_KERNEL void hash_csr_retrieve_kernel(std::int64_t output_size, |
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I don't see the logic for handling right/outer joins emission here. Is the IsOuter flag only for left joins for now?
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Following the design proposed by @rootjalex
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