# Python/Arrow boundary experiment

Diagnostic evidence; no established baseline. Seconds: median [IQR].
Consumer import and profiling are combined. Lazy stream preparation is inside that timer.
End-to-end includes both independent exports. RSS is a process lifetime high-water mark,
including imports and warmups, not per-stage allocation or a Python allocation count.

| Case (producer/rows/chunk/offset) | Condition | Prepare | Import + profile | Dict | JSON | End-to-end |
| --- | --- | --- | --- | --- | --- | --- |
| arrow_array/1000/1000/offset-0 | fresh | 0.135536 [0.003819] | 0.005084 [0.000562] | 0.000118 [0.000009] | 0.000053 [0.000014] | 0.140791 [0.003280] |
| arrow_array/1000/1000/offset-0 | warm | 0.000492 [0.000003] | 0.001317 [0.000018] | 0.000085 [0.000001] | 0.000040 [0.000000] | 0.001934 [0.000022] |
| arrow_array/1000/1000/offset-3 | fresh | 0.136664 [0.000184] | 0.004533 [0.000049] | 0.000123 [0.000006] | 0.000041 [0.000001] | 0.141361 [0.000240] |
| arrow_array/1000/1000/offset-3 | warm | 0.000485 [0.000016] | 0.001346 [0.000024] | 0.000081 [0.000002] | 0.000040 [0.000000] | 0.001952 [0.000038] |
| arrow_table/1000/250/offset-0 | fresh | 0.137592 [0.000022] | 0.005404 [0.000610] | 0.000111 [0.000002] | 0.000041 [0.000000] | 0.143149 [0.000630] |
| arrow_table/1000/250/offset-0 | warm | 0.000559 [0.000010] | 0.001392 [0.000004] | 0.000081 [0.000000] | 0.000040 [0.000001] | 0.002072 [0.000007] |
| arrow_table/1000/250/offset-3 | fresh | 0.150680 [0.022900] | 0.005096 [0.000170] | 0.000108 [0.000004] | 0.000041 [0.000001] | 0.155925 [0.023075] |
| arrow_table/1000/250/offset-3 | warm | 0.000605 [0.000031] | 0.001426 [0.000032] | 0.000087 [0.000002] | 0.000041 [0.000001] | 0.002160 [0.000066] |
| arrow_table/1000/1000/offset-0 | fresh | 0.133647 [0.003753] | 0.005536 [0.000207] | 0.000121 [0.000007] | 0.000041 [0.000001] | 0.139344 [0.003540] |
| arrow_table/1000/1000/offset-0 | warm | 0.000452 [0.000030] | 0.001355 [0.000022] | 0.000078 [0.000001] | 0.000040 [0.000001] | 0.001924 [0.000008] |
| arrow_table/1000/1000/offset-3 | fresh | 0.137791 [0.003203] | 0.005474 [0.000415] | 0.000109 [0.000003] | 0.000041 [0.000001] | 0.143415 [0.003622] |
| arrow_table/1000/1000/offset-3 | warm | 0.000450 [0.000029] | 0.001369 [0.000048] | 0.000080 [0.000000] | 0.000038 [0.000001] | 0.001938 [0.000078] |
| pandas/1000/250/offset-0 | fresh | 0.003833 [0.000113] | 0.007438 [0.001073] | 0.000098 [0.000001] | 0.000054 [0.000012] | 0.011423 [0.001175] |
| pandas/1000/250/offset-0 | warm | 0.000938 [0.000061] | 0.002005 [0.000048] | 0.000076 [0.000001] | 0.000039 [0.000001] | 0.003057 [0.000110] |
| pandas/1000/250/offset-3 | fresh | 0.004045 [0.000086] | 0.006382 [0.000138] | 0.000112 [0.000015] | 0.000043 [0.000001] | 0.010583 [0.000241] |
| pandas/1000/250/offset-3 | warm | 0.001082 [0.000022] | 0.002170 [0.000014] | 0.000077 [0.000001] | 0.000040 [0.000002] | 0.003369 [0.000038] |
| pandas/1000/1000/offset-0 | fresh | 0.003638 [0.000089] | 0.006912 [0.000136] | 0.000092 [0.000000] | 0.000040 [0.000000] | 0.010682 [0.000047] |
| pandas/1000/1000/offset-0 | warm | 0.001138 [0.000168] | 0.003028 [0.001083] | 0.000237 [0.000159] | 0.000100 [0.000045] | 0.004502 [0.001455] |
| pandas/1000/1000/offset-3 | fresh | 0.003873 [0.000081] | 0.006744 [0.000008] | 0.000097 [0.000005] | 0.000043 [0.000002] | 0.010758 [0.000092] |
| pandas/1000/1000/offset-3 | warm | 0.000911 [0.000048] | 0.002019 [0.000049] | 0.000077 [0.000002] | 0.000040 [0.000001] | 0.003047 [0.000096] |
| polars/1000/250/offset-0 | fresh | 0.138789 [0.001956] | 0.005677 [0.000005] | 0.000117 [0.000001] | 0.000041 [0.000001] | 0.144624 [0.001949] |
| polars/1000/250/offset-0 | warm | 0.000816 [0.000050] | 0.001530 [0.000010] | 0.000086 [0.000001] | 0.000043 [0.000001] | 0.002475 [0.000038] |
| polars/1000/250/offset-3 | fresh | 0.131215 [0.001698] | 0.005264 [0.000382] | 0.000113 [0.000008] | 0.000041 [0.000001] | 0.136633 [0.001325] |
| polars/1000/250/offset-3 | warm | 0.000831 [0.000019] | 0.001462 [0.000030] | 0.000091 [0.000004] | 0.000041 [0.000000] | 0.002425 [0.000046] |
| polars/1000/1000/offset-0 | fresh | 0.141028 [0.000362] | 0.005354 [0.000213] | 0.000118 [0.000006] | 0.000057 [0.000007] | 0.146557 [0.000151] |
| polars/1000/1000/offset-0 | warm | 0.000655 [0.000033] | 0.001338 [0.000003] | 0.000084 [0.000001] | 0.000040 [0.000000] | 0.002117 [0.000034] |
| polars/1000/1000/offset-3 | fresh | 0.137571 [0.010698] | 0.005695 [0.000683] | 0.000111 [0.000007] | 0.000045 [0.000003] | 0.143421 [0.011390] |
| polars/1000/1000/offset-3 | warm | 0.000660 [0.000001] | 0.001382 [0.000006] | 0.000082 [0.000005] | 0.000040 [0.000001] | 0.002164 [0.000013] |
| arrow_stream/1000/250/offset-0 | fresh | 0.000098 [0.000004] | 0.141874 [0.004780] | 0.000118 [0.000013] | 0.000043 [0.000002] | 0.142133 [0.004761] |
| arrow_stream/1000/250/offset-0 | warm | 0.000067 [0.000030] | 0.001755 [0.000071] | 0.000086 [0.000002] | 0.000039 [0.000001] | 0.001946 [0.000105] |
| arrow_stream/1000/250/offset-3 | fresh | 0.000084 [0.000010] | 0.144676 [0.006776] | 0.000100 [0.000003] | 0.000040 [0.000000] | 0.144900 [0.006790] |
| arrow_stream/1000/250/offset-3 | warm | 0.000063 [0.000026] | 0.001799 [0.000040] | 0.000084 [0.000008] | 0.000039 [0.000001] | 0.001986 [0.000076] |
| arrow_stream/1000/1000/offset-0 | fresh | 0.000089 [0.000001] | 0.138067 [0.001035] | 0.000097 [0.000000] | 0.000039 [0.000000] | 0.138292 [0.001036] |
| arrow_stream/1000/1000/offset-0 | warm | 0.000065 [0.000029] | 0.001704 [0.000050] | 0.000082 [0.000004] | 0.000041 [0.000001] | 0.001891 [0.000084] |
| arrow_stream/1000/1000/offset-3 | fresh | 0.000095 [0.000006] | 0.139350 [0.005586] | 0.000096 [0.000002] | 0.000039 [0.000000] | 0.139580 [0.005593] |
| arrow_stream/1000/1000/offset-3 | warm | 0.000066 [0.000025] | 0.001603 [0.000013] | 0.000088 [0.000008] | 0.000041 [0.000001] | 0.001798 [0.000048] |
| arrow_stream/4000/250/offset-3 | fresh | 0.000080 [0.000007] | 0.145258 [0.004314] | 0.000107 [0.000001] | 0.000041 [0.000001] | 0.145487 [0.004321] |
| arrow_stream/4000/250/offset-3 | warm | 0.000067 [0.000029] | 0.005836 [0.000030] | 0.000086 [0.000000] | 0.000042 [0.000001] | 0.006031 [0.000059] |

Skipped `arrow_array/1000/250/offset-0`: C Array exports one batch; chunked input uses Table or C Stream
Skipped `arrow_array/1000/250/offset-3`: C Array exports one batch; chunked input uses Table or C Stream

All serialized column metrics and absence match a single-batch reference exactly.
Producer preflight also verifies exact int64 values above 2^53, nulls and order.
Raw samples, warmups, preflights, memory observations and fingerprints: results.json.