rdettai commented on a change in pull request #8917:
URL: https://github.com/apache/arrow/pull/8917#discussion_r544351700
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File path: rust/datafusion/src/datasource/datasource.rs
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@@ -34,6 +35,23 @@ pub struct Statistics {
pub total_byte_size: Option<usize>,
}
+/// Indicates whether and how a filter expression can be handled by a
+/// TableProvider for table scans.
+#[derive(Debug, Clone)]
+pub enum TableProviderFilterPushDown {
+ /// The expression cannot be used by the provider.
+ Unsupported,
+ /// The expression can be used to help minimise the data retrieved,
+ /// but the provider cannot guarantee that all returned tuples
Review comment:
I agree the names are explicit!
I am challenging whether having 3 values is necessary. `Unsupported` vs
`Inexact` is something that you don't need to expose publicly here as they are
used internally by the the TableProvider when they will be passed back to the
`scan()` method (or not). Said otherwise, you can leave it to the the
implementation of `scan()` to decide what to do with the expressions, you don't
need to do it with `supports_filter_pushdown()`. Only `Exact` vs
`Unsupported|Inexact` really needs to be exposed because it is used externally
(by the planner)
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