polars 1.44.2, python 3.12.13, arm64, threads 10, POLARS_ENGINE_AFFINITY=(unset)

query                             wrong first purchase over 10 runs  median time
join -> first()                min   0.0%  median   0.0%  max   0.0%      10 ms
same, engine='in-memory'       min   0.0%  median   0.0%  max   0.0%      10 ms
join(maintain_order='left')    min   0.0%  median   0.0%  max   0.0%      10 ms
min('ts') instead of first()   min   0.0%  median   0.0%  max   0.0%      11 ms
no join, group_by -> first()   min   0.0%  median   0.0%  max   0.0%       5 ms

polars 2.1.0, python 3.12.13, arm64, threads 10, POLARS_ENGINE_AFFINITY=(unset)

query                             wrong first purchase over 10 runs  median time
join -> first()                min   0.2%  median  48.4%  max  99.1%       9 ms
same, engine='in-memory'       min   0.0%  median   0.0%  max   0.0%      10 ms
join(maintain_order='left')    min   0.0%  median   0.0%  max   0.0%      16 ms
min('ts') instead of first()   min   0.0%  median   0.0%  max   0.0%       8 ms
no join, group_by -> first()   min   0.0%  median   0.0%  max   0.0%       7 ms

polars 2.1.0, python 3.12.13, arm64, threads 2, POLARS_ENGINE_AFFINITY=(unset)

query                             wrong first purchase over 10 runs  median time
join -> first()                min   0.0%  median  37.3%  max  75.9%      14 ms
same, engine='in-memory'       min   0.0%  median   0.0%  max   0.0%      20 ms
join(maintain_order='left')    min   0.0%  median   0.0%  max   0.0%      26 ms
min('ts') instead of first()   min   0.0%  median   0.0%  max   0.0%      13 ms
no join, group_by -> first()   min   0.0%  median   0.0%  max   0.0%       8 ms

polars 2.1.0, python 3.12.13, arm64, threads 1, POLARS_ENGINE_AFFINITY=(unset)

query                             wrong first purchase over 10 runs  median time
join -> first()                min   0.0%  median   0.0%  max   0.0%      19 ms
same, engine='in-memory'       min   0.0%  median   0.0%  max   0.0%      26 ms
join(maintain_order='left')    min   0.0%  median   0.0%  max   0.0%      20 ms
min('ts') instead of first()   min   0.0%  median   0.0%  max   0.0%      19 ms
no join, group_by -> first()   min   0.0%  median   0.0%  max   0.0%      12 ms

polars 2.1.0, python 3.12.13, arm64, threads 10, POLARS_ENGINE_AFFINITY=in-memory

query                             wrong first purchase over 10 runs  median time
join -> first()                min   0.0%  median   0.0%  max   0.0%      10 ms
same, engine='in-memory'       min   0.0%  median   0.0%  max   0.0%      10 ms
join(maintain_order='left')    min   0.0%  median   0.0%  max   0.0%      11 ms
min('ts') instead of first()   min   0.0%  median   0.0%  max   0.0%      11 ms
no join, group_by -> first()   min   0.0%  median   0.0%  max   0.0%       5 ms