From ab70b02d86288dc081e1b8a0a81ff8a84e74b793 Mon Sep 17 00:00:00 2001
From: Alexey Bashtanov <alexey.bashtanov@redpanda.com>
Date: Thu, 15 Jan 2026 12:10:05 +0000
Subject: [PATCH] c/topic_table: use chunked_hash_map for lifecycle markers

to avoid oversized allocations

(cherry picked from commit efc8a8013cd693f2c11c20cdfc5092df269b2fff)
---
 src/v/cluster/archival/purger.cc    | 5 +++--
 src/v/cluster/controller_snapshot.h | 2 +-
 src/v/cluster/topic_table.cc        | 3 ++-
 src/v/cluster/topic_table.h         | 2 +-
 src/v/redpanda/admin/server.cc      | 5 +++--
 5 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/v/cluster/archival/purger.cc b/src/v/cluster/archival/purger.cc
index 8f6f70250127d..b4889dac17547 100644
--- a/src/v/cluster/archival/purger.cc
+++ b/src/v/cluster/archival/purger.cc
@@ -25,6 +25,7 @@
 #include "cluster/topics_frontend.h"
 #include "config/configuration.h"
 #include "config/node_config.h"
+#include "container/chunked_hash_map.h"
 #include "hashing/xx.h"
 
 namespace {
@@ -355,8 +356,8 @@ ss::future<housekeeping_job::run_result> purger::run(run_quota_t quota) {
     }
 
     // Take a copy, as we will iterate over it asynchronously
-    cluster::topic_table::lifecycle_markers_t markers
-      = _topic_table.get_lifecycle_markers();
+    chunked_vector<cluster::topic_table::lifecycle_markers_t::value_type>
+      markers{std::from_range, _topic_table.get_lifecycle_markers()};
 
     const auto my_global_position = get_global_position();
 
diff --git a/src/v/cluster/controller_snapshot.h b/src/v/cluster/controller_snapshot.h
index ad17400834696..0665f3b768758 100644
--- a/src/v/cluster/controller_snapshot.h
+++ b/src/v/cluster/controller_snapshot.h
@@ -184,7 +184,7 @@ struct topics_t
     chunked_hash_map<model::topic_namespace, topic_t> topics;
     raft::group_id highest_group_id;
 
-    absl::node_hash_map<
+    chunked_hash_map<
       nt_revision,
       nt_lifecycle_marker,
       nt_revision_hash,
diff --git a/src/v/cluster/topic_table.cc b/src/v/cluster/topic_table.cc
index eedac2fda7dd9..9a6ed5e78d2ee 100644
--- a/src/v/cluster/topic_table.cc
+++ b/src/v/cluster/topic_table.cc
@@ -1670,7 +1670,8 @@ ss::future<> topic_table::apply_snapshot(
 
     // Lifecycle markers is a simple static collection without notifications
     // etc, so we can just copy directly into place.
-    _lifecycle_markers = controller_snap.topics.lifecycle_markers;
+    _lifecycle_markers.replace(
+      controller_snap.topics.lifecycle_markers.values().copy());
 
     reset_partitions_to_force_reconfigure(
       controller_snap.topics.partitions_to_force_recover);
diff --git a/src/v/cluster/topic_table.h b/src/v/cluster/topic_table.h
index 812a266371a90..b1dcf143a389e 100644
--- a/src/v/cluster/topic_table.h
+++ b/src/v/cluster/topic_table.h
@@ -424,7 +424,7 @@ class topic_table {
         topic_id_mapping_t _by_id;
     };
 
-    using lifecycle_markers_t = absl::node_hash_map<
+    using lifecycle_markers_t = chunked_hash_map<
       nt_revision,
       nt_lifecycle_marker,
       nt_revision_hash,
diff --git a/src/v/redpanda/admin/server.cc b/src/v/redpanda/admin/server.cc
index e82b764591214..5efabc5182763 100644
--- a/src/v/redpanda/admin/server.cc
+++ b/src/v/redpanda/admin/server.cc
@@ -143,6 +143,7 @@
 #include <limits>
 #include <memory>
 #include <numeric>
+#include <ranges>
 #include <stdexcept>
 #include <system_error>
 #include <type_traits>
@@ -4495,8 +4496,8 @@ admin_server::get_cloud_storage_lifecycle(std::unique_ptr<ss::http::request>) {
 
     auto& topic_table = _controller->get_topics_state().local();
 
-    cluster::topic_table::lifecycle_markers_t markers
-      = topic_table.get_lifecycle_markers();
+    chunked_vector<cluster::topic_table::lifecycle_markers_t::value_type>
+      markers{std::from_range, topic_table.get_lifecycle_markers()};
 
     // Hack: persuade json response to always include the field even if empty
     response.markers._set = true;