Simplify tie-breaker start bound and doc comment

columnar/src/column/serialize.rs

@@ -31,7 +31,7 @@ pub(crate) fn serialize_generated_tie_breaker_column(
     output: &mut impl Write,
 ) -> io::Result<()> {
     // TODO: Lift this temporary u32 limit once downstream consumers support the full u64 range.
-    let max_start = u64::from(u32::MAX - num_docs.saturating_sub(1));
+    let max_start = (u32::MAX - num_docs) as u64;
     let start: u64 = rand::rng().random_range(0..=max_start);
     let end = start + num_docs as u64;
     let values = start..end;

src/schema/schema.rs

@@ -59,13 +59,11 @@ impl SchemaBuilder {
 
     /// Adds a generated tie-breaker fast field.
     ///
-    /// The field is exposed as a `u64` fast field. Its generated values are temporarily limited
-    /// to the `u32` range for downstream compatibility; this limit will eventually be lifted.
-    /// Values supplied by documents for this field are ignored.
+    /// The field is exposed as a `u64` fast field. Values are consecutive within a segment,
+    /// starting at a random offset. Ranges of different segments may overlap, so values are
+    /// almost always distinct but not guaranteed to be unique.
     ///
-    /// Values are consecutive within a segment, starting at a random offset. Ranges of
-    /// different segments may overlap, so values are almost always distinct but not
-    /// guaranteed to be unique.
+    /// Values supplied by documents for this field are ignored.
     ///
     /// # Panics
     ///