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[WIP] Use sort-merge joins based on approximate cardinality count of keys #106

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[WIP] Use sort-merge joins based on approximate cardinality count of keys #106

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7 changes: 7 additions & 0 deletions velox/experimental/cudf/CudfConfig.h
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,8 @@ struct CudfConfig {
"cudf.ast_expression_priority"};
static constexpr const char* kCudfAllowCpuFallback{"cudf.allow_cpu_fallback"};
static constexpr const char* kCudfLogFallback{"cudf.log_fallback"};
static constexpr const char* kCudfSortMergeJoinCardinalityThreshold{
"cudf.sort_merge_join.cardinality_threshold"};

/// Singleton CudfConfig instance.
/// Clients must set the configs below before invoking registerCudf().
Expand Down Expand Up @@ -78,6 +80,11 @@ struct CudfConfig {

/// Whether to log a reason for falling back to Velox CPU execution.
bool logFallback{true};

/// Cardinality threshold for sort-merge join. When the ratio of distinct keys
/// to total rows in the build table is below this threshold, sort-merge join
/// is used instead of hash join for inner and left joins.
double sortMergeJoinCardinalityThreshold{0.1};
};

} // namespace facebook::velox::cudf_velox
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