Hyper log log plus plus(HLL++) #2522
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res-life
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ttnghia
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Nov 1, 2024
src/main/cpp/src/HLLPP.cu
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| rmm::cuda_stream_view stream, | ||
| rmm::device_async_resource_ref mr) | ||
| { | ||
| CUDF_EXPECTS(precision >= 4 && precision <= 18, "HLL++ requires precision in range: [4, 18]"); |
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We can use std::numeric_limits<>::digits instead of hardcoded values 4 and 18.
ttnghia
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Nov 1, 2024
| auto input_cols = std::vector<int64_t const*>(input_iter, input_iter + input.num_children()); | ||
| auto d_inputs = cudf::detail::make_device_uvector_async(input_cols, stream, mr); | ||
| auto result = cudf::make_numeric_column( | ||
| cudf::data_type{cudf::type_id::INT64}, input.size(), cudf::mask_state::ALL_VALID, stream); |
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Do we need such all-valid null mask? How about cudf::mask_state::UNALLOCATED?
ttnghia
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Nov 1, 2024
| auto result = cudf::make_numeric_column( | ||
| cudf::data_type{cudf::type_id::INT64}, input.size(), cudf::mask_state::ALL_VALID, stream); | ||
| // evaluate from struct<long, ..., long> | ||
| thrust::for_each_n(rmm::exec_policy(stream), |
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Try to use exec_policy_nosync as much as possible.
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| thrust::for_each_n(rmm::exec_policy(stream), | |
| thrust::for_each_n(rmm::exec_policy_nosync(stream), |
ttnghia
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Nov 1, 2024
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| * The input sketch values must be given in the format `LIST<INT8>`. | ||
| * | ||
| * @param input The sketch column which constains `LIST<INT8> values. |
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In addition, in estimate_from_hll_sketches I see that the input is STRUCT<LONG, LONG, ....> instead of LIST<>. Why?
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It's STRUCT<LONG, LONG, ....> consistent with Spark. The input is columnar data, e.g.: sketch 0 is composed of by all the data of the children at index 0.
Updated the function comments, refer to commit
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