diff --git a/rust/lance-index/src/vector/pq/distance.rs b/rust/lance-index/src/vector/pq/distance.rs
index a0124012f67..9c6c25bcfc2 100644
--- a/rust/lance-index/src/vector/pq/distance.rs
+++ b/rust/lance-index/src/vector/pq/distance.rs
@@ -4,13 +4,11 @@
 use core::panic;
 use std::cmp::{max, min};
 
+use super::{num_centroids, utils::get_sub_vector_centroids};
 use lance_core::assume_eq;
 use lance_linalg::distance::{dot_distance_batch, l2_distance_batch, Dot, L2};
 use lance_linalg::simd::u8::u8x16;
 use lance_linalg::simd::{Shuffle, SIMD};
-use lance_table::utils::LanceIteratorExtension;
-
-use super::{num_centroids, utils::get_sub_vector_centroids};
 
 // for quantizing the distance table, we need to know the max possible distance,
 // so we perform a flat search on the first `FLAT_NUM_4BIT_PQ` rows.
@@ -43,16 +41,17 @@ pub fn build_distance_table_l2_impl<const NUM_BITS: u32, T: L2>(
     let dimension = query.len();
     let sub_vector_length = dimension / num_sub_vectors;
     let num_centroids = 2_usize.pow(NUM_BITS);
-    query
-        .chunks_exact(sub_vector_length)
-        .enumerate()
-        .flat_map(|(i, sub_vec)| {
-            let subvec_centroids =
-                get_sub_vector_centroids::<NUM_BITS, _>(codebook, dimension, num_sub_vectors, i);
-            l2_distance_batch(sub_vec, subvec_centroids, sub_vector_length)
-        })
-        .exact_size(num_sub_vectors * num_centroids)
-        .collect()
+    let mut result = Vec::with_capacity(num_sub_vectors * num_centroids);
+    for (i, sub_vec) in query.chunks_exact(sub_vector_length).enumerate() {
+        let subvec_centroids =
+            get_sub_vector_centroids::<NUM_BITS, _>(codebook, dimension, num_sub_vectors, i);
+        result.extend(l2_distance_batch(
+            sub_vec,
+            subvec_centroids,
+            sub_vector_length,
+        ));
+    }
+    result
 }
 
 /// Build a Distance Table from the query to each PQ centroid
@@ -79,16 +78,17 @@ pub fn build_distance_table_dot_impl<const NUM_BITS: u32, T: Dot>(
     let dimension = query.len();
     let sub_vector_length = dimension / num_sub_vectors;
     let num_centroids = 2_usize.pow(NUM_BITS);
-    query
-        .chunks_exact(sub_vector_length)
-        .enumerate()
-        .flat_map(|(i, sub_vec)| {
-            let subvec_centroids =
-                get_sub_vector_centroids::<NUM_BITS, _>(codebook, dimension, num_sub_vectors, i);
-            dot_distance_batch(sub_vec, subvec_centroids, sub_vector_length)
-        })
-        .exact_size(num_sub_vectors * num_centroids)
-        .collect()
+    let mut result = Vec::with_capacity(num_sub_vectors * num_centroids);
+    for (i, sub_vec) in query.chunks_exact(sub_vector_length).enumerate() {
+        let subvec_centroids =
+            get_sub_vector_centroids::<NUM_BITS, _>(codebook, dimension, num_sub_vectors, i);
+        result.extend(dot_distance_batch(
+            sub_vec,
+            subvec_centroids,
+            sub_vector_length,
+        ));
+    }
+    result
 }
 
 /// Compute L2 distance from the query to all code.