Merge pull request #25919 from vespa-engine/toregge/pass-optional-serial-num-to-prepare-reconfigv8.121.38

Pass optional serial num to prepare reconfig

28 files changed, 116 insertions, 65 deletions

diff --git a/searchcore/src/tests/proton/attribute/attribute_manager/attribute_manager_test.cpp b/searchcore/src/tests/proton/attribute/attribute_manager/attribute_manager_test.cpp
index 29639448023..88d0752461b 100644
--- a/searchcore/src/tests/proton/attribute/attribute_manager/attribute_manager_test.cpp
+++ b/searchcore/src/tests/proton/attribute/attribute_manager/attribute_manager_test.cpp
@@ -214,6 +214,8 @@ struct Fixture : public BaseFixture, public AttributeManagerFixture
 struct SequentialAttributeManager
 {
     SequentialAttributesInitializer initializer;
+    uint32_t                 docid_limit;
+    SerialNum                serial_num;
     proton::AttributeManager mgr;
     SequentialAttributeManager(const AttributeManager &currMgr, AttrMgrSpec && newSpec);
     ~SequentialAttributeManager();
@@ -221,9 +223,11 @@ struct SequentialAttributeManager
 
 SequentialAttributeManager::SequentialAttributeManager(const AttributeManager &currMgr, AttrMgrSpec && newSpec)
     : initializer(newSpec.getDocIdLimit()),
+      docid_limit(newSpec.getDocIdLimit()),
+      serial_num(newSpec.getCurrentSerialNum().value_or(0)),
       mgr(currMgr, std::move(newSpec), initializer)
 {
-    mgr.addInitializedAttributes(initializer.getInitializedAttributes(), std::nullopt, std::nullopt);
+    mgr.addInitializedAttributes(initializer.getInitializedAttributes(), docid_limit, serial_num);
 }
 SequentialAttributeManager::~SequentialAttributeManager() = default;
 
diff --git a/searchcore/src/tests/proton/documentdb/configurer/configurer_test.cpp b/searchcore/src/tests/proton/documentdb/configurer/configurer_test.cpp
index 2877005e2c1..d7ce042a4d3 100644
--- a/searchcore/src/tests/proton/documentdb/configurer/configurer_test.cpp
+++ b/searchcore/src/tests/proton/documentdb/configurer/configurer_test.cpp
@@ -246,7 +246,7 @@ Fixture::reconfigure(const DocumentDBConfig& new_config_snapshot,
                      IDocumentDBReferenceResolver& resolver,
                      SerialNum serial_num)
 {
-    auto prepared_reconfig = _configurer->prepare_reconfig(new_config_snapshot, old_config_snapshot, reconfig_params);
+    auto prepared_reconfig = _configurer->prepare_reconfig(new_config_snapshot, old_config_snapshot, reconfig_params, serial_num);
     _configurer->reconfigure(new_config_snapshot, old_config_snapshot, reconfig_params, resolver, *prepared_reconfig, serial_num);
 }
 
@@ -258,7 +258,7 @@ Fixture::reconfigure(const DocumentDBConfig& new_config_snapshot,
                      IDocumentDBReferenceResolver& resolver,
                      SerialNum serial_num)
 {
-    auto prepared_reconfig = _configurer->prepare_reconfig(new_config_snapshot, old_config_snapshot, reconfig_params);
+    auto prepared_reconfig = _configurer->prepare_reconfig(new_config_snapshot, old_config_snapshot, reconfig_params, serial_num);
     return _configurer->reconfigure(new_config_snapshot, old_config_snapshot, std::move(attr_spec), reconfig_params, resolver, *prepared_reconfig, serial_num);
 }
 
@@ -341,7 +341,7 @@ FastAccessFixture::reconfigure(const DocumentDBConfig& new_config_snapshot,
                                SerialNum serial_num)
 {
     ReconfigParams reconfig_params{CCR()};
-    auto prepared_reconfig = _configurer.prepare_reconfig(new_config_snapshot, old_config_snapshot, reconfig_params);
+    auto prepared_reconfig = _configurer.prepare_reconfig(new_config_snapshot, old_config_snapshot, reconfig_params, serial_num);
     return _configurer.reconfigure(new_config_snapshot, old_config_snapshot, std::move(attr_spec), *prepared_reconfig, serial_num);
 }
 
diff --git a/searchcore/src/tests/proton/documentdb/document_subdbs/document_subdbs_test.cpp b/searchcore/src/tests/proton/documentdb/document_subdbs/document_subdbs_test.cpp
index 307695c4f4b..f49c46d81e8 100644
--- a/searchcore/src/tests/proton/documentdb/document_subdbs/document_subdbs_test.cpp
+++ b/searchcore/src/tests/proton/documentdb/document_subdbs/document_subdbs_test.cpp
@@ -379,7 +379,7 @@ struct FixtureBase
         cmpResult.documentTypeRepoChanged = true;
         MyDocumentDBReferenceResolver resolver;
         ReconfigParams reconfig_params(cmpResult);
-        auto prepared_reconfig = _subDb.prepare_reconfig(*newCfg->_cfg, *_snapshot->_cfg, reconfig_params);
+        auto prepared_reconfig = _subDb.prepare_reconfig(*newCfg->_cfg, *_snapshot->_cfg, reconfig_params, serialNum);
         auto tasks = _subDb.applyConfig(*newCfg->_cfg, *_snapshot->_cfg,
                                         serialNum, reconfig_params, resolver, *prepared_reconfig);
         prepared_reconfig.reset();
diff --git a/searchcore/src/vespa/searchcore/proton/attribute/attribute_manager_initializer.cpp b/searchcore/src/vespa/searchcore/proton/attribute/attribute_manager_initializer.cpp
index c15a15e44e5..77cc1142f75 100644
--- a/searchcore/src/vespa/searchcore/proton/attribute/attribute_manager_initializer.cpp
+++ b/searchcore/src/vespa/searchcore/proton/attribute/attribute_manager_initializer.cpp
@@ -86,7 +86,7 @@ void
 AttributeManagerInitializerTask::run()
 {
     _attrMgr->addExtraAttribute(_documentMetaStore);
-    _attrMgr->addInitializedAttributes(_attributesResult.get(), std::nullopt, std::nullopt);
+    _attrMgr->addInitializedAttributes(_attributesResult.get(), 1, _configSerialNum);
     _attrMgr->pruneRemovedFields(_configSerialNum);
     _promise.set_value();
 }
diff --git a/searchcore/src/vespa/searchcore/proton/attribute/attribute_manager_reconfig.cpp b/searchcore/src/vespa/searchcore/proton/attribute/attribute_manager_reconfig.cpp
index 2942256f534..06c03c80785 100644
--- a/searchcore/src/vespa/searchcore/proton/attribute/attribute_manager_reconfig.cpp
+++ b/searchcore/src/vespa/searchcore/proton/attribute/attribute_manager_reconfig.cpp
@@ -17,7 +17,7 @@ AttributeManagerReconfig::AttributeManagerReconfig(std::shared_ptr<AttributeMana
 AttributeManagerReconfig::~AttributeManagerReconfig() = default;
 
 std::shared_ptr<AttributeManager>
-AttributeManagerReconfig::create(std::optional<uint32_t> docid_limit, std::optional<search::SerialNum> serial_num)
+AttributeManagerReconfig::create(uint32_t docid_limit, search::SerialNum serial_num)
 {
     assert(_mgr);
     _mgr->addInitializedAttributes(_initializer->getInitializedAttributes(), docid_limit, serial_num);
diff --git a/searchcore/src/vespa/searchcore/proton/attribute/attribute_manager_reconfig.h b/searchcore/src/vespa/searchcore/proton/attribute/attribute_manager_reconfig.h
index da8ae163fb5..9e4f8b71a7a 100644
--- a/searchcore/src/vespa/searchcore/proton/attribute/attribute_manager_reconfig.h
+++ b/searchcore/src/vespa/searchcore/proton/attribute/attribute_manager_reconfig.h
@@ -22,7 +22,7 @@ public:
     AttributeManagerReconfig(std::shared_ptr<AttributeManager> mgr,
                              std::unique_ptr<SequentialAttributesInitializer> initializer);
     ~AttributeManagerReconfig();
-    std::shared_ptr<AttributeManager> create(std::optional<uint32_t> docid_limit, std::optional<search::SerialNum> serial_num);
+    std::shared_ptr<AttributeManager> create(uint32_t docid_limit, search::SerialNum serial_num);
 };
 
 }
diff --git a/searchcore/src/vespa/searchcore/proton/attribute/attributemanager.cpp b/searchcore/src/vespa/searchcore/proton/attribute/attributemanager.cpp
index e27fae65de3..dd6cc1bdb85 100644
--- a/searchcore/src/vespa/searchcore/proton/attribute/attributemanager.cpp
+++ b/searchcore/src/vespa/searchcore/proton/attribute/attributemanager.cpp
@@ -325,16 +325,24 @@ AttributeManager::addAttribute(AttributeSpec && spec, uint64_t serialNum)
 }
 
 void
-AttributeManager::addInitializedAttributes(const std::vector<AttributeInitializerResult> &attributes, std::optional<uint32_t> docid_limit, std::optional<SerialNum> serial_num)
+AttributeManager::addInitializedAttributes(const std::vector<AttributeInitializerResult> &attributes, uint32_t docid_limit, SerialNum serial_num)
 {
+    /*
+     * Called (indirectly) by
+     * DocumentSubDBCollection::complete_prepare_reconfig to complete
+     * setup of new attribute manager.
+     */
     for (const auto &result : attributes) {
         assert(result);
         auto attr = result.getAttribute();
-        if (docid_limit.has_value()) {
-            AttributeManager::padAttribute(*attr, docid_limit.value());
-        }
-        if (serial_num.has_value()) {
-            attr->setCreateSerialNum(serial_num.value());
+        if (attr->getCreateSerialNum() == 0) {
+            /*
+             * The attribute vector is empty (not loaded from disk)
+             * and has been added as part of live reconfig. Make it
+             * ready for use by setting size and create serial num.
+             */
+            AttributeManager::padAttribute(*attr, docid_limit);
+            attr->setCreateSerialNum(serial_num);
         }
         attr->setInterlock(_interlock);
         auto shrinker = allocShrinker(attr, _attributeFieldWriter, *_diskLayout);
@@ -503,8 +511,10 @@ proton::IAttributeManager::SP
 AttributeManager::create(Spec&& spec) const
 {
     assert(spec.getCurrentSerialNum().has_value());
+    auto docid_limit = spec.getDocIdLimit();
+    auto serial_num = spec.getCurrentSerialNum().value();
     auto prepared_result = prepare_create(std::move(spec));
-    return prepared_result->create(std::nullopt, std::nullopt);
+    return prepared_result->create(docid_limit, serial_num);
 }
 
 std::vector<IFlushTarget::SP>
diff --git a/searchcore/src/vespa/searchcore/proton/attribute/attributemanager.h b/searchcore/src/vespa/searchcore/proton/attribute/attributemanager.h
index 35895e5422c..c8c5da7f4e4 100644
--- a/searchcore/src/vespa/searchcore/proton/attribute/attributemanager.h
+++ b/searchcore/src/vespa/searchcore/proton/attribute/attributemanager.h
@@ -123,7 +123,7 @@ public:
 
     AttributeVectorSP addAttribute(AttributeSpec && spec, uint64_t serialNum);
 
-    void addInitializedAttributes(const std::vector<AttributeInitializerResult> &attributes, std::optional<uint32_t> docid_limit, std::optional<SerialNum> serial_num);
+    void addInitializedAttributes(const std::vector<AttributeInitializerResult> &attributes, uint32_t docid_limit, SerialNum serial_num);
 
     void addExtraAttribute(const AttributeVectorSP &attribute);
 
diff --git a/searchcore/src/vespa/searchcore/proton/server/document_db_reconfig.cpp b/searchcore/src/vespa/searchcore/proton/server/document_db_reconfig.cpp
index 903c9d0a899..f0d028f924f 100644
--- a/searchcore/src/vespa/searchcore/proton/server/document_db_reconfig.cpp
+++ b/searchcore/src/vespa/searchcore/proton/server/document_db_reconfig.cpp
@@ -5,8 +5,8 @@
 
 namespace proton {
 
-DocumentDBReconfig::DocumentDBReconfig(std::unique_ptr<const DocumentSubDBReconfig> ready_reconfig_in,
-                                       std::unique_ptr<const DocumentSubDBReconfig> not_ready_reconfig_in)
+DocumentDBReconfig::DocumentDBReconfig(std::unique_ptr<DocumentSubDBReconfig> ready_reconfig_in,
+                                       std::unique_ptr<DocumentSubDBReconfig> not_ready_reconfig_in)
     : _ready_reconfig(std::move(ready_reconfig_in)),
       _not_ready_reconfig(std::move(not_ready_reconfig_in))
 {
diff --git a/searchcore/src/vespa/searchcore/proton/server/document_db_reconfig.h b/searchcore/src/vespa/searchcore/proton/server/document_db_reconfig.h
index 21ea117f7e9..d35a2211397 100644
--- a/searchcore/src/vespa/searchcore/proton/server/document_db_reconfig.h
+++ b/searchcore/src/vespa/searchcore/proton/server/document_db_reconfig.h
@@ -10,26 +10,31 @@ class DocumentSubDBReconfig;
 /**
  * Class representing the result of the prepare step of a DocumentDB reconfig.
  *
- * The reconfig is performed in two steps:
+ * The reconfig is performed in three steps:
  * Prepare:
  * Based on the config that is changed, new components are instantiated in each subdb.
  * This can be costly and is handled by helper threads from the shared executor pool.
  *
+ * Complete prepare:
+ * Docid limit and serial number are used to complete prepared reconfig.
+ *
  * Apply:
  * The new components are swapped with the old ones in the DocumentDB master write thread.
  */
 class DocumentDBReconfig {
 private:
-    std::unique_ptr<const DocumentSubDBReconfig> _ready_reconfig;
-    std::unique_ptr<const DocumentSubDBReconfig> _not_ready_reconfig;
+    std::unique_ptr<DocumentSubDBReconfig> _ready_reconfig;
+    std::unique_ptr<DocumentSubDBReconfig> _not_ready_reconfig;
 
 public:
-    DocumentDBReconfig(std::unique_ptr<const DocumentSubDBReconfig> ready_reconfig_in,
-                       std::unique_ptr<const DocumentSubDBReconfig> not_ready_reconfig_in);
+    DocumentDBReconfig(std::unique_ptr<DocumentSubDBReconfig> ready_reconfig_in,
+                       std::unique_ptr<DocumentSubDBReconfig> not_ready_reconfig_in);
     ~DocumentDBReconfig();
 
-    const DocumentSubDBReconfig& ready_reconfig() const { return *_ready_reconfig; }
-    const DocumentSubDBReconfig& not_ready_reconfig() const { return *_not_ready_reconfig; }
+    const DocumentSubDBReconfig& ready_reconfig() const noexcept { return *_ready_reconfig; }
+    DocumentSubDBReconfig& ready_reconfig() noexcept { return *_ready_reconfig; }
+    const DocumentSubDBReconfig& not_ready_reconfig() const noexcept { return *_not_ready_reconfig; }
+    DocumentSubDBReconfig& not_ready_reconfig() noexcept { return *_not_ready_reconfig; }
 };
 
 }
diff --git a/searchcore/src/vespa/searchcore/proton/server/document_subdb_reconfig.cpp b/searchcore/src/vespa/searchcore/proton/server/document_subdb_reconfig.cpp
index 2fd222338e7..60514b91aab 100644
--- a/searchcore/src/vespa/searchcore/proton/server/document_subdb_reconfig.cpp
+++ b/searchcore/src/vespa/searchcore/proton/server/document_subdb_reconfig.cpp
@@ -12,5 +12,12 @@ DocumentSubDBReconfig::DocumentSubDBReconfig(std::shared_ptr<Matchers> matchers_
 
 DocumentSubDBReconfig::~DocumentSubDBReconfig() = default;
 
+void
+DocumentSubDBReconfig::complete(uint32_t docid_limit, search::SerialNum serial_num)
+{
+    (void) docid_limit;
+    (void) serial_num;
+}
+
 }
 
diff --git a/searchcore/src/vespa/searchcore/proton/server/document_subdb_reconfig.h b/searchcore/src/vespa/searchcore/proton/server/document_subdb_reconfig.h
index 89129a6b0d0..0554056100e 100644
--- a/searchcore/src/vespa/searchcore/proton/server/document_subdb_reconfig.h
+++ b/searchcore/src/vespa/searchcore/proton/server/document_subdb_reconfig.h
@@ -1,6 +1,7 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 #pragma once
 
+#include <vespa/searchlib/common/serialnum.h>
 #include <memory>
 
 namespace proton {
@@ -26,7 +27,8 @@ public:
         return _old_matchers != _new_matchers;
     }
     std::shared_ptr<Matchers> matchers() const { return _new_matchers; }
+
+    void complete(uint32_t docid_limit, search::SerialNum serial_num);
 };
 
 }
-
diff --git a/searchcore/src/vespa/searchcore/proton/server/documentdb.cpp b/searchcore/src/vespa/searchcore/proton/server/documentdb.cpp
index 110b0324dc3..a217e3b719e 100644
--- a/searchcore/src/vespa/searchcore/proton/server/documentdb.cpp
+++ b/searchcore/src/vespa/searchcore/proton/server/documentdb.cpp
@@ -349,7 +349,7 @@ DocumentDB::initFinish(DocumentDBConfig::SP configSnapshot)
 }
 
 std::unique_ptr<DocumentDBReconfig>
-DocumentDB::prepare_reconfig(const DocumentDBConfig& new_config_snapshot)
+DocumentDB::prepare_reconfig(const DocumentDBConfig& new_config_snapshot, std::optional<SerialNum> serial_num)
 {
     auto active_config_snapshot = getActiveConfig();
     auto cmpres = active_config_snapshot->compare(new_config_snapshot);
@@ -357,7 +357,7 @@ DocumentDB::prepare_reconfig(const DocumentDBConfig& new_config_snapshot)
         cmpres.importedFieldsChanged = true;
     }
     const ReconfigParams reconfig_params(cmpres);
-    return _subDBs.prepare_reconfig(new_config_snapshot, *active_config_snapshot, reconfig_params);
+    return _subDBs.prepare_reconfig(new_config_snapshot, *active_config_snapshot, reconfig_params, serial_num);
 }
 
 void
@@ -423,7 +423,7 @@ DocumentDB::applySubDBConfig(const DocumentDBConfig &newConfigSnapshot,
 }
 
 void
-DocumentDB::applyConfig(DocumentDBConfig::SP configSnapshot, SerialNum serialNum, std::unique_ptr<const DocumentDBReconfig> prepared_reconfig)
+DocumentDB::applyConfig(DocumentDBConfig::SP configSnapshot, SerialNum serialNum, std::unique_ptr<DocumentDBReconfig> prepared_reconfig)
 {
     // Always called by executor thread:
     // Called by performReconfig() by executor thread during normal
@@ -472,6 +472,7 @@ DocumentDB::applyConfig(DocumentDBConfig::SP configSnapshot, SerialNum serialNum
         bool elidedConfigSave = equalReplayConfig && tlsReplayDone;
         forceCommitAndWait(*_feedView.get(), elidedConfigSave ? serialNum : serialNum - 1, std::move(commit_result));
     }
+    _subDBs.complete_prepare_reconfig(*prepared_reconfig, serialNum);
     if (params.shouldMaintenanceControllerChange()) {
         _maintenanceController.killJobs();
     }
@@ -796,7 +797,7 @@ DocumentDB::reconfigure(DocumentDBConfig::SP snapshot)
     assert(active_snapshot);
     assert(_state.getAllowReconfig());
     snapshot = DocumentDBConfig::makeDelayedAttributeAspectConfig(snapshot, *active_snapshot);
-    auto prepared_reconfig = prepare_reconfig(*snapshot);
+    auto prepared_reconfig = prepare_reconfig(*snapshot, std::nullopt);
     masterExecute([this, snapshot, prepared_reconfig = std::move(prepared_reconfig)]() mutable { performReconfig(snapshot, std::move(prepared_reconfig)); });
     // Wait for config to be applied, or for document db close
     std::unique_lock<std::mutex> guard(_configMutex);
@@ -835,7 +836,7 @@ DocumentDB::enterApplyLiveConfigState()
         (void) _state.enterApplyLiveConfigState();
     }
     auto new_config_snapshot = _pendingConfigSnapshot.get();
-    auto prepared_reconfig = prepare_reconfig(*new_config_snapshot);
+    auto prepared_reconfig = prepare_reconfig(*new_config_snapshot, std::nullopt);
     masterExecute([this, new_config_snapshot, prepared_reconfig = std::move(prepared_reconfig)]() mutable
                   {
                       performReconfig(std::move(new_config_snapshot), std::move(prepared_reconfig));
@@ -896,7 +897,7 @@ DocumentDB::replayConfig(search::SerialNum serialNum)
     configSnapshot = DocumentDBConfigScout::scout(configSnapshot, *_pendingConfigSnapshot.get());
     // Ignore configs that are not relevant during replay of transaction log
     configSnapshot = DocumentDBConfig::makeReplayConfig(configSnapshot);
-    auto prepared_reconfig = prepare_reconfig(*configSnapshot);
+    auto prepared_reconfig = prepare_reconfig(*configSnapshot, serialNum);
     applyConfig(configSnapshot, serialNum, std::move(prepared_reconfig));
     LOG(info, "DocumentDB(%s): Replayed config with serialNum=%" PRIu64,
               _docTypeName.toString().c_str(), serialNum);
diff --git a/searchcore/src/vespa/searchcore/proton/server/documentdb.h b/searchcore/src/vespa/searchcore/proton/server/documentdb.h
index 2b3e6ef4052..6e611917a79 100644
--- a/searchcore/src/vespa/searchcore/proton/server/documentdb.h
+++ b/searchcore/src/vespa/searchcore/proton/server/documentdb.h
@@ -156,7 +156,7 @@ private:
     void applySubDBConfig(const DocumentDBConfig &newConfigSnapshot,
                           SerialNum serialNum, const ReconfigParams &params,
                           const DocumentDBReconfig& prepared_reconfig);
-    void applyConfig(DocumentDBConfigSP configSnapshot, SerialNum serialNum, std::unique_ptr<const DocumentDBReconfig> prepared_reconfig);
+    void applyConfig(DocumentDBConfigSP configSnapshot, SerialNum serialNum, std::unique_ptr<DocumentDBReconfig> prepared_reconfig);
 
     /**
      * Save initial config if we don't have any saved config snapshots.
@@ -382,7 +382,7 @@ public:
     bool getDelayedConfig() const { return _state.getDelayedConfig(); }
     void replayConfig(SerialNum serialNum) override;
     const DocTypeName & getDocTypeName() const { return _docTypeName; }
-    std::unique_ptr<DocumentDBReconfig> prepare_reconfig(const DocumentDBConfig& new_config_snapshot);
+    std::unique_ptr<DocumentDBReconfig> prepare_reconfig(const DocumentDBConfig& new_config_snapshot, std::optional<SerialNum> serial_num);
     void reconfigure(DocumentDBConfigSP snapshot) override;
     int64_t getActiveGeneration() const;
     /*
diff --git a/searchcore/src/vespa/searchcore/proton/server/documentsubdbcollection.cpp b/searchcore/src/vespa/searchcore/proton/server/documentsubdbcollection.cpp
index 573683c21a9..73f90df11ab 100644
--- a/searchcore/src/vespa/searchcore/proton/server/documentsubdbcollection.cpp
+++ b/searchcore/src/vespa/searchcore/proton/server/documentsubdbcollection.cpp
@@ -251,14 +251,21 @@ DocumentSubDBCollection::pruneRemovedFields(SerialNum serialNum)
 }
 
 std::unique_ptr<DocumentDBReconfig>
-DocumentSubDBCollection::prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params)
+DocumentSubDBCollection::prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params, std::optional<SerialNum> serial_num)
 {
-    auto ready_reconfig = getReadySubDB()->prepare_reconfig(new_config_snapshot, old_config_snapshot, reconfig_params);
-    auto not_ready_reconfig = getNotReadySubDB()->prepare_reconfig(new_config_snapshot, old_config_snapshot, reconfig_params);
+    auto ready_reconfig = getReadySubDB()->prepare_reconfig(new_config_snapshot, old_config_snapshot, reconfig_params, serial_num);
+    auto not_ready_reconfig = getNotReadySubDB()->prepare_reconfig(new_config_snapshot, old_config_snapshot, reconfig_params, serial_num);
     return std::make_unique<DocumentDBReconfig>(std::move(ready_reconfig), std::move(not_ready_reconfig));
 }
 
 void
+DocumentSubDBCollection::complete_prepare_reconfig(DocumentDBReconfig& prepared_reconfig, SerialNum serial_num)
+{
+    getReadySubDB()->complete_prepare_reconfig(prepared_reconfig.ready_reconfig(), serial_num);
+    getNotReadySubDB()->complete_prepare_reconfig(prepared_reconfig.not_ready_reconfig(), serial_num);
+}
+
+void
 DocumentSubDBCollection::applyConfig(const DocumentDBConfig &newConfigSnapshot,
                                      const DocumentDBConfig &oldConfigSnapshot,
                                      SerialNum serialNum,
@@ -271,7 +278,7 @@ DocumentSubDBCollection::applyConfig(const DocumentDBConfig &newConfigSnapshot,
     _reprocessingRunner.addTasks(tasks);
     tasks = getNotReadySubDB()->applyConfig(newConfigSnapshot, oldConfigSnapshot, serialNum, params, resolver, prepared_reconfig.not_ready_reconfig());
     _reprocessingRunner.addTasks(tasks);
-    auto removed_reconfig = getRemSubDB()->prepare_reconfig(newConfigSnapshot, oldConfigSnapshot, params);
+    auto removed_reconfig = getRemSubDB()->prepare_reconfig(newConfigSnapshot, oldConfigSnapshot, params, serialNum);
     tasks = getRemSubDB()->applyConfig(newConfigSnapshot, oldConfigSnapshot, serialNum, params, resolver, *removed_reconfig);
     removed_reconfig.reset();
     _reprocessingRunner.addTasks(tasks);
diff --git a/searchcore/src/vespa/searchcore/proton/server/documentsubdbcollection.h b/searchcore/src/vespa/searchcore/proton/server/documentsubdbcollection.h
index 21f36c7ca3e..a359ee8f0f3 100644
--- a/searchcore/src/vespa/searchcore/proton/server/documentsubdbcollection.h
+++ b/searchcore/src/vespa/searchcore/proton/server/documentsubdbcollection.h
@@ -9,6 +9,7 @@
 #include <vespa/vespalib/util/varholder.h>
 #include <vespa/vespalib/util/idestructorcallback.h>
 #include <mutex>
+#include <optional>
 
 namespace vespalib {
     class Clock;
@@ -137,7 +138,8 @@ public:
 
     void pruneRemovedFields(SerialNum serialNum);
 
-    std::unique_ptr<DocumentDBReconfig> prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params);
+    std::unique_ptr<DocumentDBReconfig> prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params, std::optional<SerialNum> serial_num);
+    void complete_prepare_reconfig(DocumentDBReconfig& prepared_reconfig, SerialNum serial_num);
     void applyConfig(const DocumentDBConfig &newConfigSnapshot, const DocumentDBConfig &oldConfigSnapshot,
                      SerialNum serialNum, const ReconfigParams &params, IDocumentDBReferenceResolver &resolver, const DocumentDBReconfig& prepared_reconfig);
 
diff --git a/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb.cpp b/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb.cpp
index 5a2e9447f9c..eef605cea3c 100644
--- a/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb.cpp
+++ b/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb.cpp
@@ -243,10 +243,10 @@ FastAccessDocSubDB::initViews(const DocumentDBConfig &configSnapshot)
     }
 }
 
-std::unique_ptr<const DocumentSubDBReconfig>
-FastAccessDocSubDB::prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params)
+std::unique_ptr<DocumentSubDBReconfig>
+FastAccessDocSubDB::prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params, std::optional<SerialNum> serial_num)
 {
-    return _configurer.prepare_reconfig(new_config_snapshot, old_config_snapshot, reconfig_params);
+    return _configurer.prepare_reconfig(new_config_snapshot, old_config_snapshot, reconfig_params, serial_num);
 }
 
 IReprocessingTask::List
diff --git a/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb.h b/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb.h
index cec2e8595cf..e4c140e43e6 100644
--- a/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb.h
+++ b/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb.h
@@ -110,8 +110,8 @@ public:
     void setup(const DocumentSubDbInitializerResult &initResult) override;
     void initViews(const DocumentDBConfig &configSnapshot) override;
 
-    std::unique_ptr<const DocumentSubDBReconfig>
-    prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params) override;
+    std::unique_ptr<DocumentSubDBReconfig>
+    prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params, std::optional<SerialNum> serial_num) override;
     IReprocessingTask::List
     applyConfig(const DocumentDBConfig &newConfigSnapshot, const DocumentDBConfig &oldConfigSnapshot,
                 SerialNum serialNum, const ReconfigParams &params, IDocumentDBReferenceResolver &resolver, const DocumentSubDBReconfig& prepared_reconfig) override;
diff --git a/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb_configurer.cpp b/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb_configurer.cpp
index a8211d246e1..0a88b591f9f 100644
--- a/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb_configurer.cpp
+++ b/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb_configurer.cpp
@@ -45,13 +45,14 @@ FastAccessDocSubDBConfigurer::FastAccessDocSubDBConfigurer(FeedViewVarHolder &fe
 
 FastAccessDocSubDBConfigurer::~FastAccessDocSubDBConfigurer() = default;
 
-std::unique_ptr<const DocumentSubDBReconfig>
-FastAccessDocSubDBConfigurer::prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params)
+std::unique_ptr<DocumentSubDBReconfig>
+FastAccessDocSubDBConfigurer::prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params, std::optional<search::SerialNum> serial_num)
 {
     (void) new_config_snapshot;
     (void) old_config_snapshot;
     (void) reconfig_params;
-    return std::make_unique<const DocumentSubDBReconfig>(std::shared_ptr<Matchers>());
+    (void) serial_num;
+    return std::make_unique<DocumentSubDBReconfig>(std::shared_ptr<Matchers>());
 }
 
 IReprocessingInitializer::UP
diff --git a/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb_configurer.h b/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb_configurer.h
index 6d57a9cc3de..7a50aa35c81 100644
--- a/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb_configurer.h
+++ b/searchcore/src/vespa/searchcore/proton/server/fast_access_doc_subdb_configurer.h
@@ -33,7 +33,7 @@ public:
                                  const vespalib::string &subDbName);
     ~FastAccessDocSubDBConfigurer();
 
-    std::unique_ptr<const DocumentSubDBReconfig> prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params);
+    std::unique_ptr<DocumentSubDBReconfig> prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params, std::optional<search::SerialNum> serial_num);
 
     IReprocessingInitializer::UP reconfigure(const DocumentDBConfig &newConfig,
                                              const DocumentDBConfig &oldConfig,
diff --git a/searchcore/src/vespa/searchcore/proton/server/idocumentsubdb.h b/searchcore/src/vespa/searchcore/proton/server/idocumentsubdb.h
index 99804fe253f..bdf3d7c7102 100644
--- a/searchcore/src/vespa/searchcore/proton/server/idocumentsubdb.h
+++ b/searchcore/src/vespa/searchcore/proton/server/idocumentsubdb.h
@@ -7,6 +7,7 @@
 #include <vespa/searchlib/util/searchable_stats.h>
 #include <vespa/vespalib/stllike/string.h>
 #include <vespa/vespalib/util/idestructorcallback.h>
+#include <optional>
 
 namespace search::index { class Schema; }
 
@@ -79,8 +80,9 @@ public:
     virtual void setup(const DocumentSubDbInitializerResult &initResult) = 0;
     virtual void initViews(const DocumentDBConfig &configSnapshot) = 0;
 
-    virtual std::unique_ptr<const DocumentSubDBReconfig>
-    prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params) = 0;
+    virtual std::unique_ptr<DocumentSubDBReconfig>
+    prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params, std::optional<SerialNum> serial_num) = 0;
+    virtual void complete_prepare_reconfig(DocumentSubDBReconfig& prepared_reconfig, SerialNum serial_num) = 0;
     virtual IReprocessingTask::List
     applyConfig(const DocumentDBConfig &newConfigSnapshot, const DocumentDBConfig &oldConfigSnapshot,
                 SerialNum serialNum, const ReconfigParams &params, IDocumentDBReferenceResolver &resolver, const DocumentSubDBReconfig& prepared_reconfig) = 0;
diff --git a/searchcore/src/vespa/searchcore/proton/server/searchable_doc_subdb_configurer.cpp b/searchcore/src/vespa/searchcore/proton/server/searchable_doc_subdb_configurer.cpp
index a934a445470..fa4340f7659 100644
--- a/searchcore/src/vespa/searchcore/proton/server/searchable_doc_subdb_configurer.cpp
+++ b/searchcore/src/vespa/searchcore/proton/server/searchable_doc_subdb_configurer.cpp
@@ -140,10 +140,11 @@ SearchableDocSubDBConfigurer::reconfigureIndexSearchable()
     reconfigureMatchView(indexManager->getSearchable());
 }
 
-std::unique_ptr<const DocumentSubDBReconfig>
-SearchableDocSubDBConfigurer::prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params)
+std::unique_ptr<DocumentSubDBReconfig>
+SearchableDocSubDBConfigurer::prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params, std::optional<search::SerialNum> serial_num)
 {
     (void) old_config_snapshot;
+    (void) serial_num;
     auto old_matchers = _searchView.get()->getMatchers();
     auto reconfig = std::make_unique<DocumentSubDBReconfig>(std::move(old_matchers));
     if (reconfig_params.shouldMatchersChange()) {
diff --git a/searchcore/src/vespa/searchcore/proton/server/searchable_doc_subdb_configurer.h b/searchcore/src/vespa/searchcore/proton/server/searchable_doc_subdb_configurer.h
index b3ec169afeb..e6b0ebda7c1 100644
--- a/searchcore/src/vespa/searchcore/proton/server/searchable_doc_subdb_configurer.h
+++ b/searchcore/src/vespa/searchcore/proton/server/searchable_doc_subdb_configurer.h
@@ -78,7 +78,7 @@ public:
 
     void reconfigureIndexSearchable();
 
-    std::unique_ptr<const DocumentSubDBReconfig> prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params);
+    std::unique_ptr<DocumentSubDBReconfig> prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params, std::optional<search::SerialNum> serial_num);
 
     void reconfigure(const DocumentDBConfig &newConfig,
                      const DocumentDBConfig &oldConfig,
diff --git a/searchcore/src/vespa/searchcore/proton/server/searchabledocsubdb.cpp b/searchcore/src/vespa/searchcore/proton/server/searchabledocsubdb.cpp
index 89925e8a77d..187be079d03 100644
--- a/searchcore/src/vespa/searchcore/proton/server/searchabledocsubdb.cpp
+++ b/searchcore/src/vespa/searchcore/proton/server/searchabledocsubdb.cpp
@@ -132,10 +132,10 @@ reconfigureMatchingMetrics(const RankProfilesConfig &cfg)
     }
 }
 
-std::unique_ptr<const DocumentSubDBReconfig>
-SearchableDocSubDB::prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params)
+std::unique_ptr<DocumentSubDBReconfig>
+SearchableDocSubDB::prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params, std::optional<SerialNum> serial_num)
 {
-    return _configurer.prepare_reconfig(new_config_snapshot, old_config_snapshot, reconfig_params);
+    return _configurer.prepare_reconfig(new_config_snapshot, old_config_snapshot, reconfig_params, serial_num);
 }
 
 IReprocessingTask::List
diff --git a/searchcore/src/vespa/searchcore/proton/server/searchabledocsubdb.h b/searchcore/src/vespa/searchcore/proton/server/searchabledocsubdb.h
index 63100f7e6a9..522ccd69b2a 100644
--- a/searchcore/src/vespa/searchcore/proton/server/searchabledocsubdb.h
+++ b/searchcore/src/vespa/searchcore/proton/server/searchabledocsubdb.h
@@ -100,8 +100,8 @@ public:
     void setup(const DocumentSubDbInitializerResult &initResult) override;
     void initViews(const DocumentDBConfig &configSnapshot) override;
 
-    std::unique_ptr<const DocumentSubDBReconfig>
-    prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params) override;
+    std::unique_ptr<DocumentSubDBReconfig>
+    prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params, std::optional<SerialNum> serial_num) override;
     IReprocessingTask::List
     applyConfig(const DocumentDBConfig &newConfigSnapshot, const DocumentDBConfig &oldConfigSnapshot,
                 SerialNum serialNum, const ReconfigParams &params, IDocumentDBReferenceResolver &resolver, const DocumentSubDBReconfig& prepared_reconfig) override;
diff --git a/searchcore/src/vespa/searchcore/proton/server/storeonlydocsubdb.cpp b/searchcore/src/vespa/searchcore/proton/server/storeonlydocsubdb.cpp
index 22aeeec4ef6..e3cf394c143 100644
--- a/searchcore/src/vespa/searchcore/proton/server/storeonlydocsubdb.cpp
+++ b/searchcore/src/vespa/searchcore/proton/server/storeonlydocsubdb.cpp
@@ -405,13 +405,20 @@ StoreOnlyDocSubDB::getSubDbName() const {
     return vespalib::make_string("%s.%s", _owner.getName().c_str(), _subName.c_str());
 }
 
-std::unique_ptr<const DocumentSubDBReconfig>
-StoreOnlyDocSubDB::prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params)
+std::unique_ptr<DocumentSubDBReconfig>
+StoreOnlyDocSubDB::prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params, std::optional<SerialNum> serial_num)
 {
     (void) new_config_snapshot;
     (void) old_config_snapshot;
     (void) reconfig_params;
-    return std::make_unique<const DocumentSubDBReconfig>(std::shared_ptr<Matchers>());
+    (void) serial_num;
+    return std::make_unique<DocumentSubDBReconfig>(std::shared_ptr<Matchers>());
+}
+
+void
+StoreOnlyDocSubDB::complete_prepare_reconfig(DocumentSubDBReconfig& prepared_reconfig, SerialNum serial_num)
+{
+    prepared_reconfig.complete(_dms->getCommittedDocIdLimit(), serial_num);
 }
 
 IReprocessingTask::List
diff --git a/searchcore/src/vespa/searchcore/proton/server/storeonlydocsubdb.h b/searchcore/src/vespa/searchcore/proton/server/storeonlydocsubdb.h
index f547ced67c7..0abb06a76aa 100644
--- a/searchcore/src/vespa/searchcore/proton/server/storeonlydocsubdb.h
+++ b/searchcore/src/vespa/searchcore/proton/server/storeonlydocsubdb.h
@@ -200,8 +200,9 @@ public:
 
     void validateDocStore(FeedHandler & feedHandler, SerialNum serialNum) const override;
 
-    std::unique_ptr<const DocumentSubDBReconfig>
-    prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params) override;
+    std::unique_ptr<DocumentSubDBReconfig>
+    prepare_reconfig(const DocumentDBConfig& new_config_snapshot, const DocumentDBConfig& old_config_snapshot, const ReconfigParams& reconfig_params, std::optional<SerialNum> serial_num) override;
+    void complete_prepare_reconfig(DocumentSubDBReconfig& prepared_reconfig, SerialNum serial_num) override;
     IReprocessingTask::List
     applyConfig(const DocumentDBConfig &newConfigSnapshot, const DocumentDBConfig &oldConfigSnapshot,
                 SerialNum serialNum, const ReconfigParams &params, IDocumentDBReferenceResolver &resolver, const DocumentSubDBReconfig &prepared_reconfig) override;
diff --git a/searchcore/src/vespa/searchcore/proton/test/dummy_document_sub_db.h b/searchcore/src/vespa/searchcore/proton/test/dummy_document_sub_db.h
index 85315158c3c..5ab0109578c 100644
--- a/searchcore/src/vespa/searchcore/proton/test/dummy_document_sub_db.h
+++ b/searchcore/src/vespa/searchcore/proton/test/dummy_document_sub_db.h
@@ -52,9 +52,10 @@ struct DummyDocumentSubDb : public IDocumentSubDB
     }
     void setup(const DocumentSubDbInitializerResult &) override {}
     void initViews(const DocumentDBConfig &) override {}
-    std::unique_ptr<const DocumentSubDBReconfig> prepare_reconfig(const DocumentDBConfig&, const DocumentDBConfig&, const ReconfigParams&) override {
-        return std::make_unique<const DocumentSubDBReconfig>(std::shared_ptr<Matchers>());
+    std::unique_ptr<DocumentSubDBReconfig> prepare_reconfig(const DocumentDBConfig&, const DocumentDBConfig&, const ReconfigParams&, std::optional<SerialNum>) override {
+        return std::make_unique<DocumentSubDBReconfig>(std::shared_ptr<Matchers>());
     }
+    void complete_prepare_reconfig(DocumentSubDBReconfig&, SerialNum) override { }
     IReprocessingTask::List applyConfig(const DocumentDBConfig &, const DocumentDBConfig &,
                                         SerialNum, const ReconfigParams &, IDocumentDBReferenceResolver &, const DocumentSubDBReconfig&) override
     {