parquet: Add option to cache file metadata #12548
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Inspired by datafusion-examples/examples/advanced_parquet_index.rs
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Closing in favor of #12593, which actually works and doesn't require extensive changes to Datafusion. |
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Inspired by datafusion-examples/examples/advanced_parquet_index.rs
Which issue does this PR close?
This was an attempt to solve #12547, but did not achieve it, and I am not sure it is the right approach.
Rationale for this change
On every query on Parquet ables, Datafusion re-opens every file, and parses its metadata. This takes a significant time for short queries (in my use case, there is usually a single hit in the Page Index).
My goal with to make these queries near-instant. Unfortunately, I realized after writing this code that the Page Index still needs to be parsed every time, because file metadata is lost through the
listinglayer (as mentioned in #9964).So this does spare some (negligible?) time parsing metadata. I'm not sure it's worth the extra complexity, especially in
ParquetFormat. What do you think?What changes are included in this PR?
ParquetFormatcarry state (it probably deserves a renaming then...)CachedParquetFileReaderFactoryas an alternative toDefaultParquetFileReaderFactory, and made it usable through a config optionAre these changes tested?
no
Are there any user-facing changes?
Added
datafusion.execution.parquet.cache_metadata