diff --git a/memtable.hh b/memtable.hh
index da0c994d93..51085bc6bd 100644
--- a/memtable.hh
+++ b/memtable.hh
@@ -70,6 +70,14 @@ public:
         return allocator.object_memory_size_in_allocator(this) + external_memory_usage_without_rows();
     }
 
+    size_t size_in_allocator(allocation_strategy& allocator) {
+        auto size = size_in_allocator_without_rows(allocator);
+        for (auto&& v : _pe.versions()) {
+            size += v.size_in_allocator(allocator);
+        }
+        return size;
+    }
+
     struct compare {
         dht::decorated_key::less_comparator _c;
 
diff --git a/partition_version.cc b/partition_version.cc
index ef66d34e57..5e05e182d4 100644
--- a/partition_version.cc
+++ b/partition_version.cc
@@ -63,6 +63,11 @@ partition_version::~partition_version()
     }
 }
 
+size_t partition_version::size_in_allocator(allocation_strategy& allocator) const {
+    return allocator.object_memory_size_in_allocator(this) +
+           partition().external_memory_usage();
+}
+
 namespace {
 
 GCC6_CONCEPT(
diff --git a/partition_version.hh b/partition_version.hh
index dae916e802..89140e9ffa 100644
--- a/partition_version.hh
+++ b/partition_version.hh
@@ -130,6 +130,8 @@ public:
 
     bool is_referenced() const { return _backref; }
     partition_version_ref& back_reference() { return *_backref; }
+
+    size_t size_in_allocator(allocation_strategy& allocator) const;
 };
 
 using partition_version_range = anchorless_list_base_hook<partition_version>::range;