diff --git a/core/storage/btree.rs b/core/storage/btree.rs
index 002459955..d4f58151a 100644
--- a/core/storage/btree.rs
+++ b/core/storage/btree.rs
@@ -2501,22 +2501,28 @@ impl BTreeCursor {
     /// Search for a key in an Index Btree. Looking up indexes that need to be unique, we cannot compare the rowid
     pub fn key_exists_in_index(&mut self, key: &ImmutableRecord) -> Result<CursorResult<bool>> {
         return_if_io!(self.do_seek(SeekKey::IndexKey(key), SeekOp::GE));
-        if let Some(record) = self.record().as_ref() {
-            // get existing record, excluding the rowid
-            assert!(record.len() > 0);
-            let existing_key = &record.get_values()[..record.count() - 1];
-            let inserted_key_vals = &key.get_values();
-            if existing_key
-                .iter()
-                .zip(inserted_key_vals.iter())
-                .all(|(a, b)| a == b)
-            {
-                return Ok(CursorResult::Ok(true)); // duplicate
+
+        let record_opt = self.record();
+        match record_opt.as_ref() {
+            Some(record) => {
+                // Existing record found — compare prefix
+                let existing_key = &record.get_values()[..record.count().saturating_sub(1)];
+                let inserted_key_vals = &key.get_values();
+                if existing_key
+                    .iter()
+                    .zip(inserted_key_vals.iter())
+                    .all(|(a, b)| a == b)
+                {
+                    return Ok(CursorResult::Ok(true)); // duplicate
+                }
+            }
+            None => {
+                // Cursor not pointing at a record — table is empty or past last
+                return Ok(CursorResult::Ok(false));
             }
-        } else {
-            return Err(LimboError::InvalidArgument("Expected Record key".into()));
         }
-        Ok(CursorResult::Ok(false)) // no matching key found
+
+        Ok(CursorResult::Ok(false)) // not a duplicate
     }
 
     pub fn exists(&mut self, key: &OwnedValue) -> Result<CursorResult<bool>> {
diff --git a/core/translate/index.rs b/core/translate/index.rs
index c9a474cab..32d7cd2e9 100644
--- a/core/translate/index.rs
+++ b/core/translate/index.rs
@@ -62,13 +62,13 @@ pub fn translate_create_index(
         unique: unique_if_not_exists.0,
     });
 
-    // Allocate the necessary cursors.
+    // Allocate the necessary cursors:
     //
-    // 1. sqlite_schema_cursor_id - for the sqlite_schema table
-    // 2. btree_cursor_id - for the index btree
-    // 3. table_cursor_id - for the table we are creating the index on
-    // 4. sorter_cursor_id - for the sorter
-    // 5. pseudo_cursor_id - for the pseudo table to store the sorted index values
+    // 1. sqlite_schema_cursor_id - sqlite_schema table
+    // 2. btree_cursor_id         - new index btree
+    // 3. table_cursor_id         - table we are creating the index on
+    // 4. sorter_cursor_id        - sorter
+    // 5. pseudo_cursor_id        - pseudo table to store the sorted index values
     let sqlite_table = schema.get_btree_table(SQLITE_TABLEID).unwrap();
     let sqlite_schema_cursor_id = program.alloc_cursor_id(
         Some(SQLITE_TABLEID.to_owned()),
@@ -292,7 +292,7 @@ fn create_idx_stmt_to_sql(
     unique_if_not_exists: (bool, bool),
     cols: &[((usize, &Column), SortOrder)],
 ) -> String {
-    let mut sql = String::new();
+    let mut sql = String::with_capacity(128);
     sql.push_str("CREATE ");
     if unique_if_not_exists.0 {
         sql.push_str("UNIQUE ");