v4.2.1

Improvements

• Faster conversion of timestamp, date, time, timestamp with time zone, and time with time zone values in the rows of Cursor, DictCursor, S3FSCursor, and their async variants, of the timestamp with time zone, time, and time with time zone values in the rows of ArrowCursor and PolarsCursor, and of time columns in PandasCursor's CSV reads (#1308, #1312).
• With Polars 1.x, an unchunked PolarsCursor read of a CSV result no longer holds a second copy of the result file, so its peak memory returns to that of 4.1.0 (#1307, #1313).

Bug fixes

• PandasCursor no longer fails when parse_dates leaves out a time column, or when index_col names a time column (#1308, #1312).

Behavior changes

• The temporal converters parse with fromisoformat(), which accepts more ISO 8601 forms than the previous strptime() formats, such as a T separator, basic forms like 20240102, and a trailing offset. Athena does not write these forms, so only text from other sources is affected: it now converts instead of raising ValueError (#1312).
• An encoding other than UTF-8 given to PolarsCursor.execute() is not decoded for an unchunked CSV read and makes the read fail with OperationalError, as in 4.1.0. Athena writes CSV results in UTF-8 (#1313).

What's Changed

• Record the PyAthena 4.2.0 benchmark runs by @laughingman7743 in #1310
• Parse temporal text with fromisoformat and convert PandasCursor time columns after reading (GH-1308) by @laughingman7743 in #1312
• Pass the open CSV result file to Polars instead of its bytes (GH-1307) by @laughingman7743 in #1313
• Bump certifi from 2024.12.14 to 2026.10.19 by @dependabot[bot] in #1314

Full Changelog: v4.2.0...v4.2.1