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PERF: to_datetime doesn't recognise Arrow date time dtypes and converts them again #52545

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@phofl

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@phofl

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  • I have confirmed this issue exists on the latest version of pandas.

  • I have confirmed this issue exists on the main branch of pandas.

Reproducible Example

In [3]: dr = pd.date_range("2019-12-31", periods=1_000_000, freq="s").astype(pd.ArrowDtype(pa.timestamp(unit="ns")))

In [4]: %timeit pd.to_datetime(dr)
1.84 s ± 8 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)

this should be instant and not take close to 2 seconds

cc @MarcoGorelli

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main

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Arrowpyarrow functionalityDatetimeDatetime data dtypePerformanceMemory or execution speed performance

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