[GitHub] [arrow] alamb commented on a change in pull request #9342: ARROW-11405: [DataFusion] Support multiple custom logical nodes

[GitBox <gi...@apache.org>]

alamb commented on a change in pull request #9342:
URL: https://github.com/apache/arrow/pull/9342#discussion_r565655349



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File path: rust/datafusion/src/physical_plan/planner.rs
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@@ -50,29 +50,30 @@ use arrow::compute::SortOptions;
 use arrow::datatypes::{Schema, SchemaRef};
 use expressions::col;
 
-/// This trait permits the `DefaultPhysicalPlanner` to create plans for
-/// user defined `ExtensionPlanNode`s
+/// This trait exposes the ability to plan an [`ExecutionPlan`] out of a [`LogicalPlan`].
 pub trait ExtensionPlanner {
-    /// Create a physical plan for an extension node
+    /// Create a physical plan for a [`UserDefinedLogicalNode`].
+    /// This errors when the planner knows how to plan the concrete implementation of `node`
+    /// but errors while doing so, and `None` when the planner does not know how to plan the `node`
+    /// and wants to delegate the planning to another [`ExtensionPlanner`].

Review comment:
       This is a nice interface




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