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fix(bigquery): Fix timestamp scientific notation handling in _helpers.py #17278

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fix(bigquery): Fix timestamp scientific notation handling in _helpers.py #17278

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2 changes: 1 addition & 1 deletion packages/google-cloud-bigquery/google/cloud/bigquery/_helpers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -261,7 +261,7 @@ def timestamp_to_py(self, value, field) -> Union[datetime.datetime, str, None]:
return value
if _not_null(value, field):
# value will be a integer in seconds, to microsecond precision, in UTC.
return _datetime_from_microseconds(int(value))
return _datetime_from_microseconds(int(float(value)))
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@gemini-code-assist gemini-code-assist Bot May 27, 2026

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medium

Directly casting all values to float before converting to int can lead to precision loss for very large integer values (specifically, integers greater than 2^53 - 1, which corresponds to timestamps beyond the year 2285). Since BigQuery supports timestamps up to the year 9999, we should attempt to parse the value as an integer first to preserve full precision, and only fall back to float parsing if a ValueError occurs (e.g., when scientific notation or a decimal point is present).

            try:
                microseconds = int(value)
            except ValueError:
                microseconds = int(float(value))
            return _datetime_from_microseconds(microseconds)

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@pkenjora pkenjora May 27, 2026

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Sure.

return None

def datetime_to_py(self, value, field):
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