perf: make dask_write a tree reduction
#4301
| Job | Run time |
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| 1m 47s | |
| 1m 47s | |
| 3m 29s | |
| 3m 29s | |
| 4m 50s | |
| 4m 50s | |
| 2m 20s | |
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| 4m 7s | |
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| 2m 12s | |
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| 7m 7s | |
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| 3m 12s | |
| 3m 12s | |
| 8m 2s | |
| 8m 2s | |
| 6m 59s | |
| 6m 59s | |
| 7m 25s | |
| 7m 25s | |
| 7m 36s | |
| 7m 36s | |
| 4m 50s | |
| 4m 50s | |
| 6m 1s | |
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| 4m 6s | |
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| 4m 43s | |
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| 4m 14s | |
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| 5m 13s | |
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| 41s | |
| 6m 22s | |
| 21s | |
| 4m 22s | |
| 29s | |
| 4m 17s | |
| 4m 34s | |
| 4m 34s | |
| 4s | |
| 2s | |
| 3h 22m 12s |