Phoenix500526 commented on code in PR #23201:
URL: https://github.com/apache/datafusion/pull/23201#discussion_r3491386349
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datafusion/execution/src/cache/mod.rs:
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@@ -165,3 +168,145 @@ impl Display for TableScopedPath {
}
}
}
+
+/// A fingerprint of the `file_schema` used to compute a file's statistics.
+///
+/// Captures exactly the attributes that determine the layout and meaning of
+/// `Statistics::column_statistics`: each column's name, data type and
+/// nullability, in order. It deliberately excludes field/schema metadata,
which
+/// cannot affect statistics — including it would needlessly fragment the
cache.
+#[derive(Clone, Debug)]
+pub struct SchemaFingerprint {
Review Comment:
After adding the schema key hash, the performance regression was indeed
fixed. I originally wanted to profile the change to determine whether schema
key hashing is on the hot path, but my local machine is not powerful enough and
the test takes too long to complete, so I’m unable to continue profiling it for
now.
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