chore: simplification for new collector logic (#1265)

Author: georgeh0

src/builder/analyzer.rs

@@ -899,25 +899,16 @@ impl AnalyzerContext {
                     };
 
                     // Pre-compute field index mappings for efficient evaluation
-                    let field_name_to_index: HashMap<&FieldName, usize> = collector_schema
-                        .fields
+                    let field_name_to_index: HashMap<&FieldName, usize> = input_field_names
                         .iter()
                         .enumerate()
-                        .map(|(i, f)| (&f.name, i))
+                        .map(|(i, n)| (n, i))
                         .collect();
-                    let mut field_index_mapping: HashMap<usize, usize> = HashMap::new();
-                    for (input_idx, field_name) in input_field_names.iter().enumerate() {
-                        let collector_idx = field_name_to_index
-                            .get(field_name)
-                            .copied()
-                            .ok_or_else(|| {
-                                anyhow!(
-                                    "field `{}` not found in merged collector schema",
-                                    field_name
-                                )
-                            })?;
-                        field_index_mapping.insert(collector_idx, input_idx);
-                    }
+                    let field_index_mapping = collector_schema
+                        .fields
+                        .iter()
+                        .map(|field| field_name_to_index.get(&field.name).copied())
+                        .collect::<Vec<Option<usize>>>();
 
                     let collect_op = AnalyzedReactiveOp::Collect(AnalyzedCollectOp {
                         name: reactive_op_name,

src/builder/plan.rs

@@ -2,8 +2,6 @@ use crate::base::schema::FieldSchema;
 use crate::base::spec::FieldName;
 use crate::prelude::*;
 
-use std::collections::HashMap;
-
 use crate::ops::interface::*;
 use crate::utils::fingerprint::{Fingerprint, Fingerprinter};
 
@@ -97,7 +95,7 @@ pub struct AnalyzedCollectOp {
     pub collector_schema: Arc<schema::CollectorSchema>,
     pub collector_ref: AnalyzedCollectorReference,
     /// Pre-computed mapping from collector field index to input field index.
-    pub field_index_mapping: HashMap<usize, usize>,
+    pub field_index_mapping: Vec<Option<usize>>,
     /// Fingerprinter of the collector's schema. Used to decide when to reuse auto-generated UUIDs.
     pub fingerprinter: Fingerprinter,
 }

src/execution/evaluator.rs

@@ -522,13 +522,15 @@ async fn evaluate_op_scope(
                         .collect::<Result<Vec<_>>>()?;
 
                 // Create field_values vector for all fields in the merged schema
-                let mut field_values: Vec<value::Value> =
-                    vec![value::Value::Null; op.collector_schema.fields.len()];
-
-                // Use pre-computed field index mappings for O(1) field placement
-                for (&collector_idx, &input_idx) in op.field_index_mapping.iter() {
-                    field_values[collector_idx] = input_values[input_idx].clone();
-                }
+                let mut field_values = op
+                    .field_index_mapping
+                    .iter()
+                    .map(|idx| {
+                        idx.map_or(value::Value::Null, |input_idx| {
+                            input_values[input_idx].clone()
+                        })
+                    })
+                    .collect::<Vec<_>>();
 
                 // Handle auto_uuid_field (assumed to be at position 0 for efficiency)
                 if op.has_auto_uuid_field {