Wrap fetch methods in asyncio.to_thread for aio pandas/arrow/polars cursors#674
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laughingman7743 merged 4 commits intomasterfrom Feb 21, 2026
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…ursors Override fetchone(), fetchmany(), fetchall(), and __anext__() in AioPandasCursor, AioArrowCursor, and AioPolarsCursor to use asyncio.to_thread(), preventing event loop blocking when chunksize triggers lazy S3 reads. This unifies the API so all aio cursors require await for fetch operations, consistent with AioCursor and AioS3FSCursor. Fixes #672 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Tests were calling fetchone(), fetchmany(), fetchall() without await, producing "coroutine was never awaited" warnings and incorrect assertions (comparing coroutine objects instead of results). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
…ning pytest-asyncio warns that future versions will default the loop scope for async fixtures to function scope. Set it explicitly to "function" to suppress the deprecation warning and ensure consistent behavior. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
fetchone(),fetchmany(),fetchall(), and__anext__()inAioPandasCursor,AioArrowCursor, andAioPolarsCursorto wrap calls inasyncio.to_thread()chunksizetriggers lazy S3 reads (pandasTextFileReader/ polars batch generator)awaitfor fetch, consistent withAioCursorandAioS3FSCursorFixes #672
Test plan
make fmtpassesmake chkpasses (ruff lint + format + mypy)make testpassesAioPandasCursorwithchunksizeno longer blocks event loop during fetchAioPolarsCursorwithchunksizeno longer blocks event loop during fetchawait cursor.fetchone()works for all aio cursors🤖 Generated with Claude Code