Lower row group size default to 256MB - #5994
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clairemcginty wants to merge 1 commit into
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Lower row group size default to 256MB to relieve read-time memory pressure.
Note: Row group size is very much a tradeoff and there's no blanket one-size-fits-all best option. Each row group adds a bit of extra overhead to the file footer/row group dictionaries, however, for low-to-moderate cardinality datasets, the default compression algorithm (ZSTD) largely reduces any storage overhead.
Possibly we could go even smaller--Iceberg defaults to 128 MB row groups, for example. But I think this PR is a good starting point. In practice, without explicit configuration, Parquet writes over Dataflow seems to produce files in the realm of 200-300MB compressed (and 2-3x that size uncompressed)--thus, this change would result in a modest increase from 1 row group per file to 2-3.