Specify to_parquet keys explicitly to ensure ordering #3270
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Previously we used delayed functions here, which don't order things in
an obvious way. Our task ordering heuristics use keys as tie-breakers
so they were performing sub-optimally when writing parquet data to disk
In the future, when convenient, we should endeavor to make our keys look
like the following:
('name-hash', int)
| for filename, part in zip(filenames, df.to_delayed())] | ||
| token = str(uuid.uuid1().hex) | ||
| writes = [write(part, fs, path, filename, fmd, compression, partition_on, | ||
| dask_key_name=('write-parquet-%s' % token, i)) |
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...as easy as that! Perhaps this kind of thing should be documented in the devs pages.
|
I will probably wait on #3271 to deal with this |
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Previously we used delayed functions here, which don't order things in
an obvious way. Our task ordering heuristics use keys as tie-breakers
so they were performing sub-optimally when writing parquet data to disk
In the future, when convenient, we should endeavor to make our keys look
like the following:
flake8 daskdocs/source/changelog.rstfor all changesand one of the
docs/source/*-api.rstfiles for new API