diff --git a/src/datatypes/src/series.rs b/src/datatypes/src/series.rs
index e26d268a8b6..d5d11bfd5ec 100644
--- a/src/datatypes/src/series.rs
+++ b/src/datatypes/src/series.rs
@@ -17,7 +17,6 @@ pub mod samples;
 pub mod time;
 
 #[cfg(test)]
-#[path = "series/tests.rs"]
 mod tests;
 
 use std::sync::Arc;
diff --git a/src/datatypes/src/series/histogram.rs b/src/datatypes/src/series/histogram.rs
index 9b9322c2774..4aae9c2c4f3 100644
--- a/src/datatypes/src/series/histogram.rs
+++ b/src/datatypes/src/series/histogram.rs
@@ -345,14 +345,15 @@ impl Default for HistogramBatchBuilder {
 impl HistogramBatchBuilder {
     /// Creates an empty builder.
     pub fn new() -> Self {
+        // Avoid reserving Arrow's large default capacity for small histogram batches.
         Self {
-            schema: Int32Builder::new(),
-            threshold: Float64Builder::new(),
-            sum: Float64Builder::new(),
-            count: Float64Builder::new(),
-            zero: Float64Builder::new(),
-            hint: Int32Builder::new(),
-            start: Int64Builder::new(),
+            schema: Int32Builder::with_capacity(0),
+            threshold: Float64Builder::with_capacity(0),
+            sum: Float64Builder::with_capacity(0),
+            count: Float64Builder::with_capacity(0),
+            zero: Float64Builder::with_capacity(0),
+            hint: Int32Builder::with_capacity(0),
+            start: Int64Builder::with_capacity(0),
             custom: lb64(),
             po: lb32(),
             pl: lb32(),
@@ -462,14 +463,14 @@ fn preflight(r: HistogramView<'_>, rows: usize, existing: [usize; 7]) -> Result<
     )
 }
 fn lb64() -> ListBuilder<Float64Builder> {
-    ListBuilder::new(Float64Builder::new()).with_field(Arc::new(Field::new(
+    ListBuilder::new(Float64Builder::with_capacity(0)).with_field(Arc::new(Field::new(
         "item",
         DataType::Float64,
         false,
     )))
 }
 fn lb32() -> ListBuilder<Int32Builder> {
-    ListBuilder::new(Int32Builder::new()).with_field(Arc::new(Field::new(
+    ListBuilder::new(Int32Builder::with_capacity(0)).with_field(Arc::new(Field::new(
         "item",
         DataType::Int32,
         false,
@@ -489,5 +490,4 @@ fn append32(b: &mut ListBuilder<Int32Builder>, v: &[i32]) {
 }
 
 #[cfg(test)]
-#[path = "histogram/tests.rs"]
 mod tests;
diff --git a/src/datatypes/src/series/histogram/tests.rs b/src/datatypes/src/series/histogram/tests.rs
index 58d761a5ac7..c81daef0270 100644
--- a/src/datatypes/src/series/histogram/tests.rs
+++ b/src/datatypes/src/series/histogram/tests.rs
@@ -44,6 +44,16 @@ fn batch() -> Arc<HistogramBatch> {
     b.finish().unwrap()
 }
 
+#[test]
+fn tiny_histogram_batch_does_not_retain_large_default_buffers() {
+    let mut builder = HistogramBatchBuilder::new();
+    builder.push(row(None, CounterResetHint::Unknown)).unwrap();
+    let batch = builder.finish().unwrap();
+    let retained = batch.as_arrow().get_buffer_memory_size();
+
+    assert!(retained < 4096, "retained {retained} bytes");
+}
+
 #[test]
 fn builder_views_and_arrow_buffer_borrowing() {
     let empty = HistogramBatchBuilder::new();
diff --git a/src/datatypes/src/series/tests.rs b/src/datatypes/src/series/tests.rs
index bf767529a06..18ce6ceeecc 100644
--- a/src/datatypes/src/series/tests.rs
+++ b/src/datatypes/src/series/tests.rs
@@ -54,7 +54,6 @@ fn metric_identity_uses_contents_and_distinguishes_absent_from_empty() {
     assert_eq!(one.get("empty"), Some(""));
     assert_eq!(one.get("missing"), None);
     assert_eq!(one.get("__name__"), Some("cpu"));
-    assert_eq!(one.get("__name_missing"), None);
 }
 
 #[test]
diff --git a/src/datatypes/src/series/time.rs b/src/datatypes/src/series/time.rs
index 8ba6f321d50..66da94684d7 100644
--- a/src/datatypes/src/series/time.rs
+++ b/src/datatypes/src/series/time.rs
@@ -20,7 +20,6 @@ use snafu::OptionExt;
 use crate::error::{InvalidSeriesSnafu, Result};
 
 #[cfg(test)]
-#[path = "time/tests.rs"]
 mod tests;
 
 /// Value description of a non-empty, fixed-step evaluation grid.