Parquet Reader: avoid caching the compressed buffer in the ColumnReader #16263
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krlmlr
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Parquet Reader: avoid caching the compressed buffer in the ColumnReader (duckdb/duckdb#16263)
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Currently we keep the compressed buffer around, when we really only need it for a short amount of time (when we read data to then decompress it). Since we keep the compressed buffer around per column, these resizeable buffers can grow to a rather substantial amount of memory, which can lead to us using 50-100% extra memory when reading Parquet files. Destroying and re-allocating the buffer does not seem to greatly affect performance - below are ClickBench timings ran on my laptop on a single big file (which is when caching matters the most given that caches are re-instantiated between files anyway):
We can perhaps do something more clever where we keep around a single cache that we share across readers, but not for the bug-fix release.