Grow string dictionary dynamically in Parquet writer #17061
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krlmlr
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Grow string dictionary dynamically in Parquet writer (duckdb/duckdb#17061)
krlmlr
added a commit
to duckdb/duckdb-r
that referenced
this pull request
May 18, 2025
Grow string dictionary dynamically in Parquet writer (duckdb/duckdb#17061)
krlmlr
added a commit
to duckdb/duckdb-r
that referenced
this pull request
May 18, 2025
Grow string dictionary dynamically in Parquet writer (duckdb/duckdb#17061)
krlmlr
added a commit
to duckdb/duckdb-r
that referenced
this pull request
May 19, 2025
Grow string dictionary dynamically in Parquet writer (duckdb/duckdb#17061)
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The
PrimitiveDictionarythat we've added for dictionary compression in Parquet (only onmainnow, and will be released in v1.3.0) would statically allocateSTRING_DICTIONARY_PAGE_SIZE_LIMITbytes for the strings. It defaults to 1 MB. If the total string size exceeds this, DuckDB bails on dictionary compression.This is a bit restrictive, and does not work well when there are many long strings that aren't unique. This PR makes it so that we initialize at 1 MB, and then we dynamically grow until
STRING_DICTIONARY_PAGE_SIZE_LIMIT, which now defaults to 1 GB. This allows large strings to still be dictionary-compressed by our writer.