Use tree reduce for aggregation #204
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freeman-lab
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Use tree reduce for aggregation
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This PR changes the core aggregation functions to use
treeReduceinstead ofreduce. In large-scale testing, this change improved performance by anywhere from a factor of 2-5x when performing reductions (e.g.sum) on very large records (each individual record 200-500 MB), without noticeably affecting performance on reduces with much smaller records.Initial testing suggests that this change may also eliminate various memory-related errors we were encountering on large reduces, but further testing is required to confirm.