[GitHub] [arrow] alamb commented on a change in pull request #8633: ARROW-10547: Do not lose Filters with UserDefined plan nodes

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

alamb commented on a change in pull request #8633:
URL: https://github.com/apache/arrow/pull/8633#discussion_r520919459



##########
File path: rust/datafusion/src/optimizer/filter_push_down.rs
##########
@@ -126,13 +126,13 @@ impl OptimizerRule for FilterPushDown {
             }
 
             // AND filter expressions that would be placed on the same depth
-            if let Some(existing_expression) = new_filtersnew_filters.get(&new_depth) {

Review comment:
       I am not sure what was going on with this variable name, but I figured I would reduce the replication ;)

##########
File path: rust/datafusion/src/optimizer/filter_push_down.rs
##########
@@ -214,6 +214,36 @@ fn analyze_plan(plan: &LogicalPlan, depth: usize) -> Result<AnalysisResult> {
             result.break_points.insert(depth, columns);
             Ok(result)
         }
+        LogicalPlan::Extension { node } => {
+            let inputs = node.inputs();
+
+            let mut result = match inputs.len() {
+                0 => AnalysisResult {
+                    break_points: BTreeMap::new(),
+                    filters: BTreeMap::new(),
+                    projections: BTreeMap::new(),
+                },
+                1 => analyze_plan(inputs[0], depth + 1)?,
+                _ => {
+                    return Err(DataFusionError::NotImplemented(

Review comment:
       
   More generally, I am not sure how / if this filter pushdown logic will work if there are multiple child inputs as no existing LogicalPlan variant his multiple inputs at this time. We will have to handle this when / if we want to support joins as well . For now I returned a "Not Yet Implemented" type error




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