feat: ETLng extensions (#1967)

For #1599 #1597
2025-11-04 11:55:51 +00:00 · 2025-03-21 16:41:29 +00:00
parent df3f1865ae
commit 702ee0324e
25 changed files with 2167 additions and 147 deletions
--- a/src/data/BackendInterface.hpp
+++ b/src/data/BackendInterface.hpp
@@ -154,7 +154,7 @@ public:
    }
    virtual ~BackendInterface() = default;

-    // TODO: Remove this hack once old ETL is removed.
+    // TODO https://github.com/XRPLF/clio/issues/1956: Remove this hack once old ETL is removed.
    // Cache should not be exposed thru BackendInterface

    /**
@@ -648,6 +648,14 @@ public:
    virtual void
    writeAccountTransactions(std::vector<AccountTransactionsData> data) = 0;

+    /**
+     * @brief Write a new account transaction.
+     *
+     * @param record An object representing the account transaction
+     */
+    virtual void
+    writeAccountTransaction(AccountTransactionsData record) = 0;
+
    /**
     * @brief Write NFTs transactions.
     *
--- a/src/data/CassandraBackend.hpp
+++ b/src/data/CassandraBackend.hpp
@@ -46,6 +46,7 @@
 #include <xrpl/protocol/LedgerHeader.h>
 #include <xrpl/protocol/nft.h>

+#include <algorithm>
 #include <atomic>
 #include <chrono>
 #include <cstddef>
@@ -906,30 +907,42 @@ public:
        statements.reserve(data.size() * 10);  // assume 10 transactions avg

        for (auto& record : data) {
-            std::transform(
-                std::begin(record.accounts),
-                std::end(record.accounts),
-                std::back_inserter(statements),
-                [this, &record](auto&& account) {
-                    return schema_->insertAccountTx.bind(
-                        std::forward<decltype(account)>(account),
-                        std::make_tuple(record.ledgerSequence, record.transactionIndex),
-                        record.txHash
-                    );
-                }
-            );
+            std::ranges::transform(record.accounts, std::back_inserter(statements), [this, &record](auto&& account) {
+                return schema_->insertAccountTx.bind(
+                    std::forward<decltype(account)>(account),
+                    std::make_tuple(record.ledgerSequence, record.transactionIndex),
+                    record.txHash
+                );
+            });
        }

        executor_.write(std::move(statements));
    }

+    void
+    writeAccountTransaction(AccountTransactionsData record) override
+    {
+        std::vector<Statement> statements;
+        statements.reserve(record.accounts.size());
+
+        std::ranges::transform(record.accounts, std::back_inserter(statements), [this, &record](auto&& account) {
+            return schema_->insertAccountTx.bind(
+                std::forward<decltype(account)>(account),
+                std::make_tuple(record.ledgerSequence, record.transactionIndex),
+                record.txHash
+            );
+        });
+
+        executor_.write(std::move(statements));
+    }
+
    void
    writeNFTTransactions(std::vector<NFTTransactionsData> const& data) override
    {
        std::vector<Statement> statements;
        statements.reserve(data.size());

-        std::transform(std::cbegin(data), std::cend(data), std::back_inserter(statements), [this](auto const& record) {
+        std::ranges::transform(data, std::back_inserter(statements), [this](auto const& record) {
            return schema_->insertNFTTx.bind(
                record.tokenID, std::make_tuple(record.ledgerSequence, record.transactionIndex), record.txHash
            );
@@ -999,7 +1012,7 @@ public:
        std::vector<Statement> statements;
        statements.reserve(data.size());
        for (auto [mptId, holder] : data)
-            statements.push_back(schema_->insertMPTHolder.bind(std::move(mptId), std::move(holder)));
+            statements.push_back(schema_->insertMPTHolder.bind(mptId, holder));

        executor_.write(std::move(statements));
    }
--- a/src/data/DBHelpers.hpp
+++ b/src/data/DBHelpers.hpp
@@ -54,7 +54,7 @@ struct AccountTransactionsData {
     * @param meta The transaction metadata
     * @param txHash The transaction hash
     */
-    AccountTransactionsData(ripple::TxMeta& meta, ripple::uint256 const& txHash)
+    AccountTransactionsData(ripple::TxMeta const& meta, ripple::uint256 const& txHash)
        : accounts(meta.getAffectedAccounts())
        , ledgerSequence(meta.getLgrSeq())
        , transactionIndex(meta.getIndex())
--- a/src/data/LedgerCache.cpp
+++ b/src/data/LedgerCache.cpp
@@ -20,6 +20,7 @@
 #include "data/LedgerCache.hpp"

 #include "data/Types.hpp"
+#include "etlng/Models.hpp"
 #include "util/Assert.hpp"

 #include <xrpl/basics/base_uint.h>
@@ -87,6 +88,42 @@ LedgerCache::update(std::vector<LedgerObject> const& objs, uint32_t seq, bool is
    }
 }

+void
+LedgerCache::update(std::vector<etlng::model::Object> const& objs, uint32_t seq)
+{
+    if (disabled_)
+        return;
+
+    std::scoped_lock const lck{mtx_};
+    if (seq > latestSeq_) {
+        ASSERT(
+            seq == latestSeq_ + 1 || latestSeq_ == 0,
+            "New sequence must be either next or first. seq = {}, latestSeq_ = {}",
+            seq,
+            latestSeq_
+        );
+        latestSeq_ = seq;
+    }
+
+    deleted_.clear();  // previous update's deletes no longer needed
+
+    for (auto const& obj : objs) {
+        if (!obj.data.empty()) {
+            auto& e = map_[obj.key];
+            if (seq > e.seq)
+                e = {.seq = seq, .blob = obj.data};
+        } else {
+            if (map_.contains(obj.key))
+                deleted_[obj.key] = map_[obj.key];
+
+            map_.erase(obj.key);
+            if (!full_)
+                deletes_.insert(obj.key);
+        }
+    }
+    cv_.notify_all();
+}
+
 std::optional<LedgerObject>
 LedgerCache::getSuccessor(ripple::uint256 const& key, uint32_t seq) const
 {
@@ -139,6 +176,29 @@ LedgerCache::get(ripple::uint256 const& key, uint32_t seq) const
    return {e->second.blob};
 }

+std::optional<Blob>
+LedgerCache::getDeleted(ripple::uint256 const& key, uint32_t seq) const
+{
+    if (disabled_)
+        return std::nullopt;
+
+    std::shared_lock const lck{mtx_};
+    if (seq > latestSeq_)
+        return std::nullopt;
+
+    ++objectReqCounter_.get();
+
+    auto e = deleted_.find(key);
+    if (e == deleted_.end())
+        return std::nullopt;
+
+    if (seq < e->second.seq)
+        return std::nullopt;
+
+    ++objectHitCounter_.get();
+    return {e->second.blob};
+}
+
 void
 LedgerCache::setDisabled()
 {
--- a/src/data/LedgerCache.hpp
+++ b/src/data/LedgerCache.hpp
@@ -21,6 +21,7 @@

 #include "data/LedgerCacheInterface.hpp"
 #include "data/Types.hpp"
+#include "etlng/Models.hpp"
 #include "util/prometheus/Bool.hpp"
 #include "util/prometheus/Counter.hpp"
 #include "util/prometheus/Label.hpp"
@@ -29,7 +30,6 @@
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/basics/hardened_hash.h>

-#include <atomic>
 #include <condition_variable>
 #include <cstddef>
 #include <cstdint>
@@ -74,6 +74,7 @@ class LedgerCache : public LedgerCacheInterface {
    )};

    std::map<ripple::uint256, CacheEntry> map_;
+    std::map<ripple::uint256, CacheEntry> deleted_;

    mutable std::shared_mutex mtx_;
    std::condition_variable_any cv_;
@@ -94,11 +95,17 @@ class LedgerCache : public LedgerCacheInterface {

 public:
    void
-    update(std::vector<LedgerObject> const& objs, uint32_t seq, bool isBackground = false) override;
+    update(std::vector<LedgerObject> const& objs, uint32_t seq, bool isBackground) override;
+
+    void
+    update(std::vector<etlng::model::Object> const& objs, uint32_t seq) override;

    std::optional<Blob>
    get(ripple::uint256 const& key, uint32_t seq) const override;

+    std::optional<Blob>
+    getDeleted(ripple::uint256 const& key, uint32_t seq) const override;
+
    std::optional<LedgerObject>
    getSuccessor(ripple::uint256 const& key, uint32_t seq) const override;

--- a/src/data/LedgerCacheInterface.hpp
+++ b/src/data/LedgerCacheInterface.hpp
@@ -20,6 +20,7 @@
 #pragma once

 #include "data/Types.hpp"
+#include "etlng/Models.hpp"

 #include <xrpl/basics/base_uint.h>
 #include <xrpl/basics/hardened_hash.h>
@@ -55,6 +56,15 @@ public:
    virtual void
    update(std::vector<LedgerObject> const& objs, uint32_t seq, bool isBackground = false) = 0;

+    /**
+     * @brief Update the cache with new ledger objects.
+     *
+     * @param objs The ledger objects to update cache with
+     * @param seq The sequence to update cache for
+     */
+    virtual void
+    update(std::vector<etlng::model::Object> const& objs, uint32_t seq) = 0;
+
    /**
     * @brief Fetch a cached object by its key and sequence number.
     *
@@ -65,6 +75,16 @@ public:
    virtual std::optional<Blob>
    get(ripple::uint256 const& key, uint32_t seq) const = 0;

+    /**
+     * @brief Fetch a recently deleted object by its key and sequence number.
+     *
+     * @param key The key to fetch for
+     * @param seq The sequence to fetch for
+     * @return If found in deleted cache, will return the cached Blob; otherwise nullopt is returned
+     */
+    virtual std::optional<Blob>
+    getDeleted(ripple::uint256 const& key, uint32_t seq) const = 0;
+
    /**
     * @brief Gets a cached successor.
     *
--- a/src/etlng/CMakeLists.txt
+++ b/src/etlng/CMakeLists.txt
@@ -9,6 +9,10 @@ target_sources(
          impl/Loading.cpp
          impl/Monitor.cpp
          impl/TaskManager.cpp
+          impl/ext/Cache.cpp
+          impl/ext/Core.cpp
+          impl/ext/NFT.cpp
+          impl/ext/Successor.cpp
 )

 target_link_libraries(clio_etlng PUBLIC clio_data)
--- a/src/etlng/impl/ext/Cache.cpp
+++ b/src/etlng/impl/ext/Cache.cpp
@@ -0,0 +1,59 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2025, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include "etlng/impl/ext/Cache.hpp"
+
+#include "data/LedgerCacheInterface.hpp"
+#include "etlng/Models.hpp"
+#include "util/log/Logger.hpp"
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+namespace etlng::impl {
+
+CacheExt::CacheExt(data::LedgerCacheInterface& cache) : cache_(cache)
+{
+}
+
+void
+CacheExt::onLedgerData(model::LedgerData const& data) const
+{
+    cache_.get().update(data.objects, data.seq);
+    LOG(log_.trace()) << "got data. objects cnt = " << data.objects.size();
+}
+
+void
+CacheExt::onInitialData(model::LedgerData const& data) const
+{
+    LOG(log_.trace()) << "got initial data. objects cnt = " << data.objects.size();
+    cache_.get().update(data.objects, data.seq);
+    cache_.get().setFull();
+}
+
+void
+CacheExt::onInitialObjects(uint32_t seq, std::vector<model::Object> const& objs, [[maybe_unused]] std::string lastKey)
+    const
+{
+    LOG(log_.trace()) << "got initial objects cnt = " << objs.size();
+    cache_.get().update(objs, seq);
+}
+
+}  // namespace etlng::impl
--- a/src/etlng/impl/ext/Cache.hpp
+++ b/src/etlng/impl/ext/Cache.hpp
@@ -0,0 +1,51 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2025, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#pragma once
+
+#include "data/LedgerCacheInterface.hpp"
+#include "etlng/Models.hpp"
+#include "util/log/Logger.hpp"
+
+#include <cstdint>
+#include <functional>
+#include <string>
+#include <vector>
+
+namespace etlng::impl {
+
+class CacheExt {
+    std::reference_wrapper<data::LedgerCacheInterface> cache_;
+
+    util::Logger log_{"ETL"};
+
+public:
+    CacheExt(data::LedgerCacheInterface& cache);
+
+    void
+    onLedgerData(model::LedgerData const& data) const;
+
+    void
+    onInitialData(model::LedgerData const& data) const;
+
+    void
+    onInitialObjects(uint32_t seq, std::vector<model::Object> const& objs, [[maybe_unused]] std::string lastKey) const;
+};
+
+}  // namespace etlng::impl
--- a/src/etlng/impl/ext/Core.cpp
+++ b/src/etlng/impl/ext/Core.cpp
@@ -0,0 +1,85 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2025, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include "etlng/impl/ext/Core.hpp"
+
+#include "data/BackendInterface.hpp"
+#include "etlng/Models.hpp"
+#include "util/log/Logger.hpp"
+
+#include <xrpl/basics/base_uint.h>
+
+#include <cstdint>
+#include <memory>
+#include <utility>
+
+namespace etlng::impl {
+
+CoreExt::CoreExt(std::shared_ptr<BackendInterface> backend) : backend_(std::move(backend))
+{
+}
+
+void
+CoreExt::onLedgerData(model::LedgerData const& data) const
+{
+    LOG(log_.debug()) << "Loading ledger data for " << data.seq;
+    backend_->writeLedger(data.header, auto{data.rawHeader});
+    insertTransactions(data);
+}
+
+void
+CoreExt::onInitialData(model::LedgerData const& data) const
+{
+    LOG(log_.info()) << "Loading initial ledger data for " << data.seq;
+    backend_->writeLedger(data.header, auto{data.rawHeader});
+    insertTransactions(data);
+}
+
+void
+CoreExt::onInitialObject(uint32_t seq, model::Object const& obj) const
+{
+    LOG(log_.trace()) << "got initial OBJ = " << obj.key << " for seq " << seq;
+    backend_->writeLedgerObject(auto{obj.keyRaw}, seq, auto{obj.dataRaw});
+}
+
+void
+CoreExt::onObject(uint32_t seq, model::Object const& obj) const
+{
+    LOG(log_.trace()) << "got OBJ = " << obj.key << " for seq " << seq;
+    backend_->writeLedgerObject(auto{obj.keyRaw}, seq, auto{obj.dataRaw});
+}
+
+void
+CoreExt::insertTransactions(model::LedgerData const& data) const
+{
+    for (auto const& txn : data.transactions) {
+        LOG(log_.trace()) << "Inserting transaction = " << txn.sttx.getTransactionID();
+
+        backend_->writeAccountTransaction({txn.meta, txn.sttx.getTransactionID()});
+        backend_->writeTransaction(
+            auto{txn.key},
+            data.seq,
+            data.header.closeTime.time_since_epoch().count(),  // This is why we can't use 'onTransaction'
+            auto{txn.raw},
+            auto{txn.metaRaw}
+        );
+    }
+}
+
+}  // namespace etlng::impl
--- a/src/etlng/impl/ext/Core.hpp
+++ b/src/etlng/impl/ext/Core.hpp
@@ -0,0 +1,58 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2025, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#pragma once
+
+#include "data/BackendInterface.hpp"
+#include "etlng/Models.hpp"
+#include "util/log/Logger.hpp"
+
+#include <xrpl/basics/base_uint.h>
+
+#include <cstdint>
+#include <memory>
+
+namespace etlng::impl {
+
+class CoreExt {
+    std::shared_ptr<BackendInterface> backend_;
+
+    util::Logger log_{"ETL"};
+
+public:
+    CoreExt(std::shared_ptr<BackendInterface> backend);
+
+    void
+    onLedgerData(model::LedgerData const& data) const;
+
+    void
+    onInitialData(model::LedgerData const& data) const;
+
+    void
+    onInitialObject(uint32_t seq, model::Object const& obj) const;
+
+    void
+    onObject(uint32_t seq, model::Object const& obj) const;
+
+private:
+    void
+    insertTransactions(model::LedgerData const& data) const;
+};
+
+}  // namespace etlng::impl
--- a/src/etlng/impl/ext/NFT.cpp
+++ b/src/etlng/impl/ext/NFT.cpp
@@ -0,0 +1,77 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2025, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include "etlng/impl/ext/NFT.hpp"
+
+#include "data/BackendInterface.hpp"
+#include "data/DBHelpers.hpp"
+#include "etl/NFTHelpers.hpp"
+#include "etlng/Models.hpp"
+#include "util/log/Logger.hpp"
+
+#include <cstdint>
+#include <memory>
+#include <utility>
+#include <vector>
+
+namespace etlng::impl {
+
+NFTExt::NFTExt(std::shared_ptr<BackendInterface> backend) : backend_(std::move(backend))
+{
+}
+
+void
+NFTExt::onLedgerData(model::LedgerData const& data) const
+{
+    writeNFTs(data);
+}
+
+void
+NFTExt::onInitialObject(uint32_t seq, model::Object const& obj) const
+{
+    LOG(log_.trace()) << "got initial object with key = " << obj.key;
+    backend_->writeNFTs(etl::getNFTDataFromObj(seq, obj.keyRaw, obj.dataRaw));
+}
+
+void
+NFTExt::onInitialData(model::LedgerData const& data) const
+{
+    LOG(log_.trace()) << "got initial TXS cnt = " << data.transactions.size();
+    writeNFTs(data);
+}
+
+void
+NFTExt::writeNFTs(model::LedgerData const& data) const
+{
+    std::vector<NFTsData> nfts;
+    std::vector<NFTTransactionsData> nftTxs;
+
+    for (auto const& tx : data.transactions) {
+        auto const [txs, maybeNFT] = etl::getNFTDataFromTx(tx.meta, tx.sttx);
+        nftTxs.insert(nftTxs.end(), txs.begin(), txs.end());
+        if (maybeNFT)
+            nfts.push_back(*maybeNFT);
+    }
+
+    // This is uniqued so that we only write latest modification (as in previous implementation)
+    backend_->writeNFTs(etl::getUniqueNFTsDatas(nfts));
+    backend_->writeNFTTransactions(nftTxs);
+}
+
+}  // namespace etlng::impl
--- a/src/etlng/impl/ext/NFT.hpp
+++ b/src/etlng/impl/ext/NFT.hpp
@@ -0,0 +1,56 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2025, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#pragma once
+
+#include "data/BackendInterface.hpp"
+#include "data/DBHelpers.hpp"
+#include "etl/NFTHelpers.hpp"
+#include "etlng/Models.hpp"
+#include "util/log/Logger.hpp"
+
+#include <cstdint>
+#include <memory>
+#include <utility>
+#include <vector>
+
+namespace etlng::impl {
+
+class NFTExt {
+    std::shared_ptr<BackendInterface> backend_;
+    util::Logger log_{"ETL"};
+
+public:
+    NFTExt(std::shared_ptr<BackendInterface> backend);
+
+    void
+    onLedgerData(model::LedgerData const& data) const;
+
+    void
+    onInitialObject(uint32_t seq, model::Object const& obj) const;
+
+    void
+    onInitialData(model::LedgerData const& data) const;
+
+private:
+    void
+    writeNFTs(model::LedgerData const& data) const;
+};
+
+}  // namespace etlng::impl
--- a/src/etlng/impl/ext/Successor.cpp
+++ b/src/etlng/impl/ext/Successor.cpp
@@ -0,0 +1,222 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2025, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include "etlng/impl/ext/Successor.hpp"
+
+#include "data/BackendInterface.hpp"
+#include "data/DBHelpers.hpp"
+#include "data/LedgerCacheInterface.hpp"
+#include "data/Types.hpp"
+#include "etlng/Models.hpp"
+#include "util/Assert.hpp"
+#include "util/log/Logger.hpp"
+
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/basics/strHex.h>
+
+#include <cstdint>
+#include <memory>
+#include <optional>
+#include <ranges>
+#include <stdexcept>
+#include <string>
+#include <utility>
+#include <vector>
+
+namespace etlng::impl {
+
+SuccessorExt::SuccessorExt(std::shared_ptr<BackendInterface> backend, data::LedgerCacheInterface& cache)
+    : backend_(std::move(backend)), cache_(cache)
+{
+}
+
+void
+SuccessorExt::onInitialData(model::LedgerData const& data) const
+{
+    ASSERT(cache_.get().isFull(), "Cache must be full at this point");
+    ASSERT(data.edgeKeys.has_value(), "Expecting to have edge keys on initial data load");
+    ASSERT(data.objects.empty(), "Should not have objects from initial data");
+    writeSuccessors(data.seq);
+    writeEdgeKeys(data.seq, data.edgeKeys.value());
+}
+
+void
+SuccessorExt::onInitialObjects(
+    uint32_t seq,
+    [[maybe_unused]] std::vector<model::Object> const& objs,
+    std::string lastKey
+) const
+{
+    for (auto const& obj : objs) {
+        if (!lastKey.empty())
+            backend_->writeSuccessor(std::move(lastKey), seq, auto{obj.keyRaw});
+        lastKey = obj.keyRaw;
+    }
+}
+
+void
+SuccessorExt::onLedgerData(model::LedgerData const& data) const
+{
+    namespace vs = std::views;
+
+    LOG(log_.info()) << "Received ledger data for successor ext; obj cnt = " << data.objects.size()
+                     << "; got successors = " << data.successors.has_value() << "; cache is "
+                     << (cache_.get().isFull() ? "FULL" : "Not full");
+
+    auto filteredObjects = data.objects  //
+        | vs::filter([](auto const& obj) { return obj.type != model::Object::ModType::Modified; });
+
+    if (data.successors.has_value()) {
+        for (auto const& successor : data.successors.value())
+            writeIncludedSuccessor(data.seq, successor);
+
+        for (auto const& obj : filteredObjects)
+            writeIncludedSuccessor(data.seq, obj);
+    } else {
+        if (not cache_.get().isFull() or cache_.get().latestLedgerSequence() != data.seq)
+            throw std::logic_error("Cache is not full, but object neighbors were not included");
+
+        for (auto const& obj : filteredObjects)
+            updateSuccessorFromCache(data.seq, obj);
+    }
+}
+
+void
+SuccessorExt::writeIncludedSuccessor(uint32_t seq, model::BookSuccessor const& succ) const
+{
+    auto firstBook = succ.firstBook;
+    if (firstBook.empty())
+        firstBook = uint256ToString(data::kLAST_KEY);
+
+    backend_->writeSuccessor(auto{succ.bookBase}, seq, std::move(firstBook));
+}
+
+void
+SuccessorExt::writeIncludedSuccessor(uint32_t seq, model::Object const& obj) const
+{
+    ASSERT(obj.type != model::Object::ModType::Modified, "Attempt to write successor for a modified object");
+
+    // TODO: perhaps make these optionals inside of obj and move value_or here
+    auto pred = obj.predecessor;
+    auto succ = obj.successor;
+
+    if (obj.type == model::Object::ModType::Deleted) {
+        backend_->writeSuccessor(std::move(pred), seq, std::move(succ));
+    } else if (obj.type == model::Object::ModType::Created) {
+        backend_->writeSuccessor(std::move(pred), seq, auto{obj.keyRaw});
+        backend_->writeSuccessor(auto{obj.keyRaw}, seq, std::move(succ));
+    }
+}
+
+void
+SuccessorExt::updateSuccessorFromCache(uint32_t seq, model::Object const& obj) const
+{
+    auto const lb =
+        cache_.get().getPredecessor(obj.key, seq).value_or(data::LedgerObject{.key = data::kFIRST_KEY, .blob = {}});
+    auto const ub =
+        cache_.get().getSuccessor(obj.key, seq).value_or(data::LedgerObject{.key = data::kLAST_KEY, .blob = {}});
+
+    auto checkBookBase = false;
+    auto const isDeleted = obj.data.empty();
+
+    if (isDeleted) {
+        backend_->writeSuccessor(uint256ToString(lb.key), seq, uint256ToString(ub.key));
+    } else {
+        backend_->writeSuccessor(uint256ToString(lb.key), seq, uint256ToString(obj.key));
+        backend_->writeSuccessor(uint256ToString(obj.key), seq, uint256ToString(ub.key));
+    }
+
+    if (isDeleted) {
+        auto const old = cache_.get().getDeleted(obj.key, seq - 1);
+        ASSERT(old.has_value(), "Deleted object {} must be in cache", ripple::strHex(obj.key));
+
+        checkBookBase = isBookDir(obj.key, *old);
+    } else {
+        checkBookBase = isBookDir(obj.key, obj.data);
+    }
+
+    if (checkBookBase) {
+        auto const current = cache_.get().get(obj.key, seq);
+        auto const bookBase = getBookBase(obj.key);
+
+        if (isDeleted and not current.has_value()) {
+            updateBookSuccessor(cache_.get().getSuccessor(bookBase, seq), seq, bookBase);
+        } else if (current.has_value()) {
+            auto const successor = cache_.get().getSuccessor(bookBase, seq);
+            ASSERT(successor.has_value(), "Book base must have a successor for seq = {}", seq);
+
+            if (successor->key == obj.key) {
+                updateBookSuccessor(successor, seq, bookBase);
+            }
+        }
+    }
+}
+
+void
+SuccessorExt::updateBookSuccessor(
+    std::optional<data::LedgerObject> const& maybeSuccessor,
+    auto seq,
+    ripple::uint256 const& bookBase
+) const
+{
+    if (maybeSuccessor.has_value()) {
+        backend_->writeSuccessor(uint256ToString(bookBase), seq, uint256ToString(maybeSuccessor->key));
+    } else {
+        backend_->writeSuccessor(uint256ToString(bookBase), seq, uint256ToString(data::kLAST_KEY));
+    }
+}
+
+void
+SuccessorExt::writeSuccessors(uint32_t seq) const
+{
+    ripple::uint256 prev = data::kFIRST_KEY;
+    while (auto cur = cache_.get().getSuccessor(prev, seq)) {
+        if (prev == data::kFIRST_KEY)
+            backend_->writeSuccessor(uint256ToString(prev), seq, uint256ToString(cur->key));
+
+        if (isBookDir(cur->key, cur->blob)) {
+            auto base = getBookBase(cur->key);
+
+            // make sure the base is not an actual object
+            if (not cache_.get().get(base, seq)) {
+                auto succ = cache_.get().getSuccessor(base, seq);
+                ASSERT(succ.has_value(), "Book base {} must have a successor", ripple::strHex(base));
+
+                if (succ->key == cur->key)
+                    backend_->writeSuccessor(uint256ToString(base), seq, uint256ToString(cur->key));
+            }
+        }
+
+        prev = cur->key;
+    }
+
+    backend_->writeSuccessor(uint256ToString(prev), seq, uint256ToString(data::kLAST_KEY));
+}
+
+void
+SuccessorExt::writeEdgeKeys(std::uint32_t seq, auto const& edgeKeys) const
+{
+    for (auto const& key : edgeKeys) {
+        auto succ = cache_.get().getSuccessor(*ripple::uint256::fromVoidChecked(key), seq);
+        if (succ)
+            backend_->writeSuccessor(auto{key}, seq, uint256ToString(succ->key));
+    }
+}
+
+}  // namespace etlng::impl
--- a/src/etlng/impl/ext/Successor.hpp
+++ b/src/etlng/impl/ext/Successor.hpp
@@ -0,0 +1,82 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2025, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#pragma once
+
+#include "data/BackendInterface.hpp"
+#include "data/LedgerCacheInterface.hpp"
+#include "data/Types.hpp"
+#include "etlng/Models.hpp"
+#include "util/log/Logger.hpp"
+
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/basics/strHex.h>
+
+#include <cstdint>
+#include <functional>
+#include <memory>
+#include <optional>
+#include <string>
+#include <vector>
+
+namespace etlng::impl {
+
+class SuccessorExt {
+    std::shared_ptr<BackendInterface> backend_;
+    std::reference_wrapper<data::LedgerCacheInterface> cache_;
+
+    util::Logger log_{"ETL"};
+
+public:
+    SuccessorExt(std::shared_ptr<BackendInterface> backend, data::LedgerCacheInterface& cache);
+
+    void
+    onInitialData(model::LedgerData const& data) const;
+
+    void
+    onInitialObjects(uint32_t seq, [[maybe_unused]] std::vector<model::Object> const& objs, std::string lastKey) const;
+
+    void
+    onLedgerData(model::LedgerData const& data) const;
+
+private:
+    void
+    writeIncludedSuccessor(uint32_t seq, model::BookSuccessor const& succ) const;
+
+    void
+    writeIncludedSuccessor(uint32_t seq, model::Object const& obj) const;
+
+    void
+    updateSuccessorFromCache(uint32_t seq, model::Object const& obj) const;
+
+    void
+    updateBookSuccessor(
+        std::optional<data::LedgerObject> const& maybeSuccessor,
+        auto seq,
+        ripple::uint256 const& bookBase
+    ) const;
+
+    void
+    writeSuccessors(uint32_t seq) const;
+
+    void
+    writeEdgeKeys(std::uint32_t seq, auto const& edgeKeys) const;
+};
+
+}  // namespace etlng::impl
--- a/tests/common/util/BinaryTestObject.cpp
+++ b/tests/common/util/BinaryTestObject.cpp
@@ -19,134 +19,31 @@

 #include "util/BinaryTestObject.hpp"

+#include "data/DBHelpers.hpp"
 #include "etlng/Models.hpp"
 #include "etlng/impl/Extraction.hpp"
 #include "util/StringUtils.hpp"
+#include "util/TestObject.hpp"

 #include <gtest/gtest.h>
 #include <org/xrpl/rpc/v1/ledger.pb.h>
+#include <xrpl/basics/Blob.h>
+#include <xrpl/basics/StringUtilities.h>
 #include <xrpl/basics/base_uint.h>
 #include <xrpl/proto/org/xrpl/rpc/v1/get_ledger.pb.h>
+#include <xrpl/protocol/AccountID.h>
 #include <xrpl/protocol/STTx.h>
 #include <xrpl/protocol/Serializer.h>
 #include <xrpl/protocol/TxFormats.h>
 #include <xrpl/protocol/TxMeta.h>

+#include <optional>
 #include <string>
 #include <utility>

 namespace {

 constinit auto const kSEQ = 30;
-
-constinit auto const kTXN_HEX =
-    "1200192200000008240011CC9B201B001F71D6202A0000000168400000"
-    "000000000C7321ED475D1452031E8F9641AF1631519A58F7B8681E172E"
-    "4838AA0E59408ADA1727DD74406960041F34F10E0CBB39444B4D4E577F"
-    "C0B7E8D843D091C2917E96E7EE0E08B30C91413EC551A2B8A1D405E8BA"
-    "34FE185D8B10C53B40928611F2DE3B746F0303751868747470733A2F2F"
-    "677265677765697362726F642E636F6D81146203F49C21D5D6E022CB16"
-    "DE3538F248662FC73C";
-
-constinit auto const kTXN_META =
-    "201C00000001F8E511005025001F71B3556ED9C9459001E4F4A9121F4E"
-    "07AB6D14898A5BBEF13D85C25D743540DB59F3CF566203F49C21D5D6E0"
-    "22CB16DE3538F248662FC73CFFFFFFFFFFFFFFFFFFFFFFFFE6FAEC5A00"
-    "0800006203F49C21D5D6E022CB16DE3538F248662FC73C8962EFA00000"
-    "0006751868747470733A2F2F677265677765697362726F642E636F6DE1"
-    "EC5A000800006203F49C21D5D6E022CB16DE3538F248662FC73C93E8B1"
-    "C200000028751868747470733A2F2F677265677765697362726F642E63"
-    "6F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F248662FC73C"
-    "9808B6B90000001D751868747470733A2F2F677265677765697362726F"
-    "642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F24866"
-    "2FC73C9C28BBAC00000012751868747470733A2F2F6772656777656973"
-    "62726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538"
-    "F248662FC73CA048C0A300000007751868747470733A2F2F6772656777"
-    "65697362726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16"
-    "DE3538F248662FC73CAACE82C500000029751868747470733A2F2F6772"
-    "65677765697362726F642E636F6DE1EC5A000800006203F49C21D5D6E0"
-    "22CB16DE3538F248662FC73CAEEE87B80000001E751868747470733A2F"
-    "2F677265677765697362726F642E636F6DE1EC5A000800006203F49C21"
-    "D5D6E022CB16DE3538F248662FC73CB30E8CAF00000013751868747470"
-    "733A2F2F677265677765697362726F642E636F6DE1EC5A000800006203"
-    "F49C21D5D6E022CB16DE3538F248662FC73CB72E91A200000008751868"
-    "747470733A2F2F677265677765697362726F642E636F6DE1EC5A000800"
-    "006203F49C21D5D6E022CB16DE3538F248662FC73CC1B453C40000002A"
-    "751868747470733A2F2F677265677765697362726F642E636F6DE1EC5A"
-    "000800006203F49C21D5D6E022CB16DE3538F248662FC73CC5D458BB00"
-    "00001F751868747470733A2F2F677265677765697362726F642E636F6D"
-    "E1EC5A000800006203F49C21D5D6E022CB16DE3538F248662FC73CC9F4"
-    "5DAE00000014751868747470733A2F2F677265677765697362726F642E"
-    "636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F248662FC7"
-    "3CCE1462A500000009751868747470733A2F2F67726567776569736272"
-    "6F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F248"
-    "662FC73CD89A24C70000002B751868747470733A2F2F67726567776569"
-    "7362726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE35"
-    "38F248662FC73CDCBA29BA00000020751868747470733A2F2F67726567"
-    "7765697362726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB"
-    "16DE3538F248662FC73CE0DA2EB100000015751868747470733A2F2F67"
-    "7265677765697362726F642E636F6DE1EC5A000800006203F49C21D5D6"
-    "E022CB16DE3538F248662FC73CE4FA33A40000000A751868747470733A"
-    "2F2F677265677765697362726F642E636F6DE1EC5A000800006203F49C"
-    "21D5D6E022CB16DE3538F248662FC73CF39FFABD000000217518687474"
-    "70733A2F2F677265677765697362726F642E636F6DE1EC5A0008000062"
-    "03F49C21D5D6E022CB16DE3538F248662FC73CF7BFFFB0000000167518"
-    "68747470733A2F2F677265677765697362726F642E636F6DE1EC5A0008"
-    "00006203F49C21D5D6E022CB16DE3538F248662FC73CFBE004A7000000"
-    "0B751868747470733A2F2F677265677765697362726F642E636F6DE1F1"
-    "E1E72200000000501A6203F49C21D5D6E022CB16DE3538F248662FC73C"
-    "662FC73C8962EFA000000006FAEC5A000800006203F49C21D5D6E022CB"
-    "16DE3538F248662FC73C8962EFA000000006751868747470733A2F2F67"
-    "7265677765697362726F642E636F6DE1EC5A000800006203F49C21D5D6"
-    "E022CB16DE3538F248662FC73C93E8B1C200000028751868747470733A"
-    "2F2F677265677765697362726F642E636F6DE1EC5A000800006203F49C"
-    "21D5D6E022CB16DE3538F248662FC73C9808B6B90000001D7518687474"
-    "70733A2F2F677265677765697362726F642E636F6DE1EC5A0008000062"
-    "03F49C21D5D6E022CB16DE3538F248662FC73C9C28BBAC000000127518"
-    "68747470733A2F2F677265677765697362726F642E636F6DE1EC5A0008"
-    "00006203F49C21D5D6E022CB16DE3538F248662FC73CA048C0A3000000"
-    "07751868747470733A2F2F677265677765697362726F642E636F6DE1EC"
-    "5A000800006203F49C21D5D6E022CB16DE3538F248662FC73CAACE82C5"
-    "00000029751868747470733A2F2F677265677765697362726F642E636F"
-    "6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F248662FC73CAE"
-    "EE87B80000001E751868747470733A2F2F677265677765697362726F64"
-    "2E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F248662F"
-    "C73CB30E8CAF00000013751868747470733A2F2F677265677765697362"
-    "726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F2"
-    "48662FC73CB72E91A200000008751868747470733A2F2F677265677765"
-    "697362726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE"
-    "3538F248662FC73CC1B453C40000002A751868747470733A2F2F677265"
-    "677765697362726F642E636F6DE1EC5A000800006203F49C21D5D6E022"
-    "CB16DE3538F248662FC73CC5D458BB0000001F751868747470733A2F2F"
-    "677265677765697362726F642E636F6DE1EC5A000800006203F49C21D5"
-    "D6E022CB16DE3538F248662FC73CC9F45DAE0000001475186874747073"
-    "3A2F2F677265677765697362726F642E636F6DE1EC5A000800006203F4"
-    "9C21D5D6E022CB16DE3538F248662FC73CCE1462A50000000975186874"
-    "7470733A2F2F677265677765697362726F642E636F6DE1EC5A00080000"
-    "6203F49C21D5D6E022CB16DE3538F248662FC73CD89A24C70000002B75"
-    "1868747470733A2F2F677265677765697362726F642E636F6DE1EC5A00"
-    "0800006203F49C21D5D6E022CB16DE3538F248662FC73CDCBA29BA0000"
-    "0020751868747470733A2F2F677265677765697362726F642E636F6DE1"
-    "EC5A000800006203F49C21D5D6E022CB16DE3538F248662FC73CE0DA2E"
-    "B100000015751868747470733A2F2F677265677765697362726F642E63"
-    "6F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F248662FC73C"
-    "E4FA33A40000000A751868747470733A2F2F677265677765697362726F"
-    "642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F24866"
-    "2FC73CEF7FF5C60000002C751868747470733A2F2F6772656777656973"
-    "62726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538"
-    "F248662FC73CF39FFABD00000021751868747470733A2F2F6772656777"
-    "65697362726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16"
-    "DE3538F248662FC73CF7BFFFB000000016751868747470733A2F2F6772"
-    "65677765697362726F642E636F6DE1EC5A000800006203F49C21D5D6E0"
-    "22CB16DE3538F248662FC73CFBE004A70000000B751868747470733A2F"
-    "2F677265677765697362726F642E636F6DE1F1E1E1E511006125001F71"
-    "B3556ED9C9459001E4F4A9121F4E07AB6D14898A5BBEF13D85C25D7435"
-    "40DB59F3CF56BE121B82D5812149D633F605EB07265A80B762A365CE94"
-    "883089FEEE4B955701E6240011CC9B202B0000002C6240000002540BE3"
-    "ECE1E72200000000240011CC9C2D0000000A202B0000002D202C000000"
-    "066240000002540BE3E081146203F49C21D5D6E022CB16DE3538F24866"
-    "2FC73CE1E1F1031000";
-
 constinit auto const kRAW_HEADER =
    "03C3141A01633CD656F91B4EBB5EB89B791BD34DBC8A04BB6F407C5335BC54351E"
    "DD733898497E809E04074D14D271E4832D7888754F9230800761563A292FA2315A"
@@ -159,27 +56,27 @@ constinit auto const kRAW_HEADER =
 namespace util {

 std::pair<std::string, std::string>
-createNftTxAndMetaBlobs()
+createNftTxAndMetaBlobs(std::string metaStr, std::string txnStr)
 {
-    return {hexStringToBinaryString(kTXN_META), hexStringToBinaryString(kTXN_HEX)};
+    return {hexStringToBinaryString(metaStr), hexStringToBinaryString(txnStr)};
 }

 std::pair<ripple::STTx, ripple::TxMeta>
-createNftTxAndMeta()
+createNftTxAndMeta(std::string hashStr, std::string metaStr, std::string txnStr)
 {
    ripple::uint256 hash;
-    EXPECT_TRUE(hash.parseHex("6C7F69A6D25A13AC4A2E9145999F45D4674F939900017A96885FDC2757E9284E"));
+    EXPECT_TRUE(hash.parseHex(hashStr));

-    auto const [metaBlob, txnBlob] = createNftTxAndMetaBlobs();
+    auto const [metaBlob, txnBlob] = createNftTxAndMetaBlobs(metaStr, txnStr);

    ripple::SerialIter it{txnBlob.data(), txnBlob.size()};
    return {ripple::STTx{it}, ripple::TxMeta{hash, kSEQ, metaBlob}};
 }

 etlng::model::Transaction
-createTransaction(ripple::TxType type)
+createTransaction(ripple::TxType type, std::string hashStr, std::string metaStr, std::string txnStr)
 {
-    auto const [sttx, meta] = createNftTxAndMeta();
+    auto const [sttx, meta] = createNftTxAndMeta(hashStr, metaStr, txnStr);
    return {
        .raw = "",
        .metaRaw = "",
@@ -192,10 +89,9 @@ createTransaction(ripple::TxType type)
 }

 etlng::model::Object
-createObject()
+createObject(etlng::model::Object::ModType modType, std::string key)
 {
    // random object taken from initial ledger load
-    static constinit auto const kOBJ_KEY = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960D";
    static constinit auto const kOBJ_PRED = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960A";
    static constinit auto const kOBJ_SUCC = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960F";
    static constinit auto const kOBJ_BLOB =
@@ -205,12 +101,62 @@ createObject()
        "8BB63367D6C38D7EA4C680004C4A505900000000000000000000000000000000C8056BA4E36038A8A0D2C0A86963153E95A84D56";

    return {
-        .key = {},
-        .keyRaw = hexStringToBinaryString(kOBJ_KEY),
-        .data = {},
-        .dataRaw = hexStringToBinaryString(kOBJ_BLOB),
+        .key = binaryStringToUint256(hexStringToBinaryString(key)),
+        .keyRaw = hexStringToBinaryString(key),
+        .data = modType == etlng::model::Object::ModType::Deleted ? ripple::Blob{} : *ripple::strUnHex(kOBJ_BLOB),
+        .dataRaw = modType == etlng::model::Object::ModType::Deleted ? "" : hexStringToBinaryString(kOBJ_BLOB),
        .successor = hexStringToBinaryString(kOBJ_SUCC),
        .predecessor = hexStringToBinaryString(kOBJ_PRED),
+        .type = modType,
+    };
+}
+
+etlng::model::Object
+createObjectWithBookBase(etlng::model::Object::ModType modType, std::string key)
+{
+    // random object taken from initial ledger load
+    static constinit auto const kOBJ_PRED = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960A";
+    static constinit auto const kOBJ_SUCC = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960F";
+    static constinit auto const kOBJ_BLOB =
+        "11006422000000022505A681E855B4E076DD06D6D583804F9DC94F641337ECB97F71860300EEC17E530A2001D6C9583FFBFAD704E299BE"
+        "3E544090ECCB12AF45FD03CAEEA852E5048E57F48FD45B505A0008138882D0F98C64A1A0E6D15053589771AD08B8C13D5384FBDAE20000"
+        "0948011320AC38AE866862CF5A8AF3578C600CEE8BFB894596584B60C0FFA7D22248E33CC3";
+
+    return {
+        .key = binaryStringToUint256(hexStringToBinaryString(key)),
+        .keyRaw = hexStringToBinaryString(key),
+        .data = modType == etlng::model::Object::ModType::Deleted ? ripple::Blob{} : *ripple::strUnHex(kOBJ_BLOB),
+        .dataRaw = modType == etlng::model::Object::ModType::Deleted ? "" : hexStringToBinaryString(kOBJ_BLOB),
+        .successor = hexStringToBinaryString(kOBJ_SUCC),
+        .predecessor = hexStringToBinaryString(kOBJ_PRED),
+        .type = modType,
+    };
+}
+
+etlng::model::Object
+createObjectWithTwoNFTs()
+{
+    std::string const url1 = "abcd1";
+    std::string const url2 = "abcd2";
+    ripple::Blob const uri1Blob(url1.begin(), url1.end());
+    ripple::Blob const uri2Blob(url2.begin(), url2.end());
+
+    constexpr auto kACCOUNT = "rM2AGCCCRb373FRuD8wHyUwUsh2dV4BW5Q";
+    constexpr auto kNFT_ID = "0008013AE1CD8B79A8BCB52335CD40DE97401B2D60A828720000099B00000000";
+    constexpr auto kNFT_ID2 = "05FB0EB4B899F056FA095537C5817163801F544BAFCEA39C995D76DB4D16F9DA";
+
+    auto const nftPage = createNftTokenPage({{kNFT_ID, url1}, {kNFT_ID2, url2}}, std::nullopt);
+    auto const serializerNftPage = nftPage.getSerializer();
+
+    auto const account = getAccountIdWithString(kACCOUNT);
+    return {
+        .key = {},
+        .keyRaw = std::string(reinterpret_cast<char const*>(account.data()), ripple::AccountID::size()),
+        .data = {},
+        .dataRaw =
+            std::string(static_cast<char const*>(serializerNftPage.getDataPtr()), serializerNftPage.getDataLength()),
+        .successor = "",
+        .predecessor = "",
        .type = etlng::model::Object::ModType::Created,
    };
 }
@@ -219,8 +165,10 @@ etlng::model::BookSuccessor
 createSuccessor()
 {
    return {
-        .firstBook = "A000000000000000000000000000000000000000000000000000000000000000",
-        .bookBase = "A000000000000000000000000000000000000000000000000000000000000001",
+        .firstBook =
+            uint256ToString(ripple::uint256{"A000000000000000000000000000000000000000000000000000000000000000"}),
+        .bookBase =
+            uint256ToString(ripple::uint256{"A000000000000000000000000000000000000000000000000000000000000001"}),
    };
 }

--- a/tests/common/util/BinaryTestObject.hpp
+++ b/tests/common/util/BinaryTestObject.hpp
@@ -32,17 +32,149 @@

 namespace util {

+static constexpr auto kDEFAULT_TXN_HEX =
+    "1200192200000008240011CC9B201B001F71D6202A0000000168400000"
+    "000000000C7321ED475D1452031E8F9641AF1631519A58F7B8681E172E"
+    "4838AA0E59408ADA1727DD74406960041F34F10E0CBB39444B4D4E577F"
+    "C0B7E8D843D091C2917E96E7EE0E08B30C91413EC551A2B8A1D405E8BA"
+    "34FE185D8B10C53B40928611F2DE3B746F0303751868747470733A2F2F"
+    "677265677765697362726F642E636F6D81146203F49C21D5D6E022CB16"
+    "DE3538F248662FC73C";
+
+static constexpr auto kDEFAULT_TXN_META =
+    "201C00000001F8E511005025001F71B3556ED9C9459001E4F4A9121F4E"
+    "07AB6D14898A5BBEF13D85C25D743540DB59F3CF566203F49C21D5D6E0"
+    "22CB16DE3538F248662FC73CFFFFFFFFFFFFFFFFFFFFFFFFE6FAEC5A00"
+    "0800006203F49C21D5D6E022CB16DE3538F248662FC73C8962EFA00000"
+    "0006751868747470733A2F2F677265677765697362726F642E636F6DE1"
+    "EC5A000800006203F49C21D5D6E022CB16DE3538F248662FC73C93E8B1"
+    "C200000028751868747470733A2F2F677265677765697362726F642E63"
+    "6F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F248662FC73C"
+    "9808B6B90000001D751868747470733A2F2F677265677765697362726F"
+    "642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F24866"
+    "2FC73C9C28BBAC00000012751868747470733A2F2F6772656777656973"
+    "62726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538"
+    "F248662FC73CA048C0A300000007751868747470733A2F2F6772656777"
+    "65697362726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16"
+    "DE3538F248662FC73CAACE82C500000029751868747470733A2F2F6772"
+    "65677765697362726F642E636F6DE1EC5A000800006203F49C21D5D6E0"
+    "22CB16DE3538F248662FC73CAEEE87B80000001E751868747470733A2F"
+    "2F677265677765697362726F642E636F6DE1EC5A000800006203F49C21"
+    "D5D6E022CB16DE3538F248662FC73CB30E8CAF00000013751868747470"
+    "733A2F2F677265677765697362726F642E636F6DE1EC5A000800006203"
+    "F49C21D5D6E022CB16DE3538F248662FC73CB72E91A200000008751868"
+    "747470733A2F2F677265677765697362726F642E636F6DE1EC5A000800"
+    "006203F49C21D5D6E022CB16DE3538F248662FC73CC1B453C40000002A"
+    "751868747470733A2F2F677265677765697362726F642E636F6DE1EC5A"
+    "000800006203F49C21D5D6E022CB16DE3538F248662FC73CC5D458BB00"
+    "00001F751868747470733A2F2F677265677765697362726F642E636F6D"
+    "E1EC5A000800006203F49C21D5D6E022CB16DE3538F248662FC73CC9F4"
+    "5DAE00000014751868747470733A2F2F677265677765697362726F642E"
+    "636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F248662FC7"
+    "3CCE1462A500000009751868747470733A2F2F67726567776569736272"
+    "6F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F248"
+    "662FC73CD89A24C70000002B751868747470733A2F2F67726567776569"
+    "7362726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE35"
+    "38F248662FC73CDCBA29BA00000020751868747470733A2F2F67726567"
+    "7765697362726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB"
+    "16DE3538F248662FC73CE0DA2EB100000015751868747470733A2F2F67"
+    "7265677765697362726F642E636F6DE1EC5A000800006203F49C21D5D6"
+    "E022CB16DE3538F248662FC73CE4FA33A40000000A751868747470733A"
+    "2F2F677265677765697362726F642E636F6DE1EC5A000800006203F49C"
+    "21D5D6E022CB16DE3538F248662FC73CF39FFABD000000217518687474"
+    "70733A2F2F677265677765697362726F642E636F6DE1EC5A0008000062"
+    "03F49C21D5D6E022CB16DE3538F248662FC73CF7BFFFB0000000167518"
+    "68747470733A2F2F677265677765697362726F642E636F6DE1EC5A0008"
+    "00006203F49C21D5D6E022CB16DE3538F248662FC73CFBE004A7000000"
+    "0B751868747470733A2F2F677265677765697362726F642E636F6DE1F1"
+    "E1E72200000000501A6203F49C21D5D6E022CB16DE3538F248662FC73C"
+    "662FC73C8962EFA000000006FAEC5A000800006203F49C21D5D6E022CB"
+    "16DE3538F248662FC73C8962EFA000000006751868747470733A2F2F67"
+    "7265677765697362726F642E636F6DE1EC5A000800006203F49C21D5D6"
+    "E022CB16DE3538F248662FC73C93E8B1C200000028751868747470733A"
+    "2F2F677265677765697362726F642E636F6DE1EC5A000800006203F49C"
+    "21D5D6E022CB16DE3538F248662FC73C9808B6B90000001D7518687474"
+    "70733A2F2F677265677765697362726F642E636F6DE1EC5A0008000062"
+    "03F49C21D5D6E022CB16DE3538F248662FC73C9C28BBAC000000127518"
+    "68747470733A2F2F677265677765697362726F642E636F6DE1EC5A0008"
+    "00006203F49C21D5D6E022CB16DE3538F248662FC73CA048C0A3000000"
+    "07751868747470733A2F2F677265677765697362726F642E636F6DE1EC"
+    "5A000800006203F49C21D5D6E022CB16DE3538F248662FC73CAACE82C5"
+    "00000029751868747470733A2F2F677265677765697362726F642E636F"
+    "6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F248662FC73CAE"
+    "EE87B80000001E751868747470733A2F2F677265677765697362726F64"
+    "2E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F248662F"
+    "C73CB30E8CAF00000013751868747470733A2F2F677265677765697362"
+    "726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F2"
+    "48662FC73CB72E91A200000008751868747470733A2F2F677265677765"
+    "697362726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE"
+    "3538F248662FC73CC1B453C40000002A751868747470733A2F2F677265"
+    "677765697362726F642E636F6DE1EC5A000800006203F49C21D5D6E022"
+    "CB16DE3538F248662FC73CC5D458BB0000001F751868747470733A2F2F"
+    "677265677765697362726F642E636F6DE1EC5A000800006203F49C21D5"
+    "D6E022CB16DE3538F248662FC73CC9F45DAE0000001475186874747073"
+    "3A2F2F677265677765697362726F642E636F6DE1EC5A000800006203F4"
+    "9C21D5D6E022CB16DE3538F248662FC73CCE1462A50000000975186874"
+    "7470733A2F2F677265677765697362726F642E636F6DE1EC5A00080000"
+    "6203F49C21D5D6E022CB16DE3538F248662FC73CD89A24C70000002B75"
+    "1868747470733A2F2F677265677765697362726F642E636F6DE1EC5A00"
+    "0800006203F49C21D5D6E022CB16DE3538F248662FC73CDCBA29BA0000"
+    "0020751868747470733A2F2F677265677765697362726F642E636F6DE1"
+    "EC5A000800006203F49C21D5D6E022CB16DE3538F248662FC73CE0DA2E"
+    "B100000015751868747470733A2F2F677265677765697362726F642E63"
+    "6F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F248662FC73C"
+    "E4FA33A40000000A751868747470733A2F2F677265677765697362726F"
+    "642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538F24866"
+    "2FC73CEF7FF5C60000002C751868747470733A2F2F6772656777656973"
+    "62726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16DE3538"
+    "F248662FC73CF39FFABD00000021751868747470733A2F2F6772656777"
+    "65697362726F642E636F6DE1EC5A000800006203F49C21D5D6E022CB16"
+    "DE3538F248662FC73CF7BFFFB000000016751868747470733A2F2F6772"
+    "65677765697362726F642E636F6DE1EC5A000800006203F49C21D5D6E0"
+    "22CB16DE3538F248662FC73CFBE004A70000000B751868747470733A2F"
+    "2F677265677765697362726F642E636F6DE1F1E1E1E511006125001F71"
+    "B3556ED9C9459001E4F4A9121F4E07AB6D14898A5BBEF13D85C25D7435"
+    "40DB59F3CF56BE121B82D5812149D633F605EB07265A80B762A365CE94"
+    "883089FEEE4B955701E6240011CC9B202B0000002C6240000002540BE3"
+    "ECE1E72200000000240011CC9C2D0000000A202B0000002D202C000000"
+    "066240000002540BE3E081146203F49C21D5D6E022CB16DE3538F24866"
+    "2FC73CE1E1F1031000";
+
+static constexpr auto kDEFAULT_HASH = "6C7F69A6D25A13AC4A2E9145999F45D4674F939900017A96885FDC2757E9284E";
+static constexpr auto kDEFAULT_OBJ_KEY = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960D";
+
 [[maybe_unused, nodiscard]] std::pair<std::string, std::string>
-createNftTxAndMetaBlobs();
+createNftTxAndMetaBlobs(std::string metaStr = kDEFAULT_TXN_META, std::string txnStr = kDEFAULT_TXN_HEX);

 [[maybe_unused, nodiscard]] std::pair<ripple::STTx, ripple::TxMeta>
-createNftTxAndMeta();
+createNftTxAndMeta(
+    std::string hashStr = kDEFAULT_HASH,
+    std::string metaStr = kDEFAULT_TXN_META,
+    std::string txnStr = kDEFAULT_TXN_HEX
+);

 [[maybe_unused, nodiscard]] etlng::model::Transaction
-createTransaction(ripple::TxType type);
+createTransaction(
+    ripple::TxType type,
+    std::string hashStr = kDEFAULT_HASH,
+    std::string metaStr = kDEFAULT_TXN_META,
+    std::string txnStr = kDEFAULT_TXN_HEX
+);

 [[maybe_unused, nodiscard]] etlng::model::Object
-createObject();
+createObject(
+    etlng::model::Object::ModType modType = etlng::model::Object::ModType::Created,
+    std::string key = kDEFAULT_OBJ_KEY
+);
+
+[[maybe_unused, nodiscard]] etlng::model::Object
+createObjectWithBookBase(
+    etlng::model::Object::ModType modType = etlng::model::Object::ModType::Created,
+    std::string key = kDEFAULT_OBJ_KEY
+);
+
+[[maybe_unused, nodiscard]] etlng::model::Object
+createObjectWithTwoNFTs();

 [[maybe_unused, nodiscard]] etlng::model::BookSuccessor
 createSuccessor();
--- a/tests/common/util/MockBackend.hpp
+++ b/tests/common/util/MockBackend.hpp
@@ -203,6 +203,8 @@ struct MockBackend : public BackendInterface {

    MOCK_METHOD(void, writeAccountTransactions, (std::vector<AccountTransactionsData>), (override));

+    MOCK_METHOD(void, writeAccountTransaction, (AccountTransactionsData), (override));
+
    MOCK_METHOD(void, writeNFTTransactions, (std::vector<NFTTransactionsData> const&), (override));

    MOCK_METHOD(void, writeSuccessor, (std::string && key, std::uint32_t const, std::string&&), (override));
--- a/tests/common/util/MockLedgerCache.hpp
+++ b/tests/common/util/MockLedgerCache.hpp
@@ -21,6 +21,7 @@

 #include "data/LedgerCacheInterface.hpp"
 #include "data/Types.hpp"
+#include "etlng/Models.hpp"

 #include <gmock/gmock.h>
 #include <xrpl/basics/base_uint.h>
@@ -41,6 +42,10 @@ struct MockLedgerCache : data::LedgerCacheInterface {

    MOCK_METHOD(std::optional<data::Blob>, get, (ripple::uint256 const& a, uint32_t b), (const, override));

+    MOCK_METHOD(void, update, (std::vector<etlng::model::Object> const&, uint32_t), (override));
+
+    MOCK_METHOD(std::optional<data::Blob>, getDeleted, (ripple::uint256 const&, uint32_t), (const, override));
+
    MOCK_METHOD(
        std::optional<data::LedgerObject>,
        getSuccessor,
--- a/tests/unit/CMakeLists.txt
+++ b/tests/unit/CMakeLists.txt
@@ -45,6 +45,10 @@ target_sources(
          etlng/LoadingTests.cpp
          etlng/NetworkValidatedLedgersTests.cpp
          etlng/MonitorTests.cpp
+          etlng/ext/CoreTests.cpp
+          etlng/ext/CacheTests.cpp
+          etlng/ext/NFTTests.cpp
+          etlng/ext/SuccessorTests.cpp
          # Feed
          util/BytesConverterTests.cpp
          feed/BookChangesFeedTests.cpp
--- a/tests/unit/etlng/ext/CacheTests.cpp
+++ b/tests/unit/etlng/ext/CacheTests.cpp
@@ -0,0 +1,92 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2025, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include "etlng/Models.hpp"
+#include "etlng/impl/ext/Cache.hpp"
+#include "util/BinaryTestObject.hpp"
+#include "util/MockLedgerCache.hpp"
+#include "util/MockPrometheus.hpp"
+#include "util/TestObject.hpp"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <xrpl/protocol/TxFormats.h>
+
+#include <utility>
+#include <vector>
+
+using namespace etlng::impl;
+using namespace data;
+
+namespace {
+constinit auto const kSEQ = 123u;
+constinit auto const kLEDGER_HASH = "4BC50C9B0D8515D3EAAE1E74B29A95804346C491EE1A95BF25E4AAB854A6A652";
+constinit auto const kUNUSED_LAST_KEY = "unused";
+
+auto
+createTestData()
+{
+    auto objects = std::vector{util::createObject(), util::createObject(), util::createObject()};
+    auto const header = createLedgerHeader(kLEDGER_HASH, kSEQ);
+    return etlng::model::LedgerData{
+        .transactions = {},
+        .objects = std::move(objects),
+        .successors = {},
+        .edgeKeys = {},
+        .header = header,
+        .rawHeader = {},
+        .seq = kSEQ
+    };
+}
+
+}  // namespace
+
+struct CacheExtTests : util::prometheus::WithPrometheus {
+protected:
+    MockLedgerCache cache_;
+    etlng::impl::CacheExt ext_{cache_};
+};
+
+TEST_F(CacheExtTests, OnLedgerDataUpdatesCache)
+{
+    auto const data = createTestData();
+
+    EXPECT_CALL(cache_, update(data.objects, data.seq));
+
+    ext_.onLedgerData(data);
+}
+
+TEST_F(CacheExtTests, OnInitialDataUpdatesCacheAndSetsFull)
+{
+    auto const data = createTestData();
+
+    EXPECT_CALL(cache_, update(data.objects, data.seq));
+    EXPECT_CALL(cache_, setFull);
+
+    ext_.onInitialData(data);
+}
+
+TEST_F(CacheExtTests, OnInitialObjectsUpdateCache)
+{
+    auto const objects = std::vector{util::createObject(), util::createObject()};
+
+    EXPECT_CALL(cache_, update(objects, kSEQ));
+
+    ext_.onInitialObjects(kSEQ, objects, kUNUSED_LAST_KEY);
+}
--- a/tests/unit/etlng/ext/CoreTests.cpp
+++ b/tests/unit/etlng/ext/CoreTests.cpp
@@ -0,0 +1,107 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2025, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include "etlng/Models.hpp"
+#include "etlng/impl/ext/Core.hpp"
+#include "util/BinaryTestObject.hpp"
+#include "util/MockBackendTestFixture.hpp"
+#include "util/MockPrometheus.hpp"
+#include "util/TestObject.hpp"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <xrpl/protocol/TxFormats.h>
+
+#include <utility>
+#include <vector>
+
+using namespace etlng::impl;
+using namespace data;
+
+namespace {
+constinit auto const kSEQ = 123u;
+constinit auto const kLEDGER_HASH = "4BC50C9B0D8515D3EAAE1E74B29A95804346C491EE1A95BF25E4AAB854A6A652";
+
+auto
+createTestData()
+{
+    auto transactions = std::vector{
+        util::createTransaction(ripple::TxType::ttNFTOKEN_BURN),
+        util::createTransaction(ripple::TxType::ttNFTOKEN_BURN),
+        util::createTransaction(ripple::TxType::ttNFTOKEN_CREATE_OFFER),
+    };
+
+    auto const header = createLedgerHeader(kLEDGER_HASH, kSEQ);
+    return etlng::model::LedgerData{
+        .transactions = std::move(transactions),
+        .objects = {},
+        .successors = {},
+        .edgeKeys = {},
+        .header = header,
+        .rawHeader = {},
+        .seq = kSEQ
+    };
+}
+
+}  // namespace
+
+struct CoreExtTests : util::prometheus::WithPrometheus, MockBackendTest {
+protected:
+    etlng::impl::CoreExt ext_{backend_};
+};
+
+TEST_F(CoreExtTests, OnLedgerDataWritesLedgerAndTransactions)
+{
+    auto const data = createTestData();
+
+    EXPECT_CALL(*backend_, writeLedger(testing::_, auto{data.rawHeader}));
+    EXPECT_CALL(*backend_, writeAccountTransaction).Times(data.transactions.size());
+    EXPECT_CALL(*backend_, writeTransaction).Times(data.transactions.size());
+
+    ext_.onLedgerData(data);
+}
+
+TEST_F(CoreExtTests, OnInitialDataWritesLedgerAndTransactions)
+{
+    auto const data = createTestData();
+
+    EXPECT_CALL(*backend_, writeLedger(testing::_, auto{data.rawHeader}));
+    EXPECT_CALL(*backend_, writeAccountTransaction).Times(data.transactions.size());
+    EXPECT_CALL(*backend_, writeTransaction).Times(data.transactions.size());
+
+    ext_.onInitialData(data);
+}
+
+TEST_F(CoreExtTests, OnInitialObjectWritesLedgerObject)
+{
+    auto const data = util::createObject();
+
+    EXPECT_CALL(*backend_, writeLedgerObject(auto{data.keyRaw}, kSEQ, auto{data.dataRaw}));
+
+    ext_.onInitialObject(kSEQ, data);
+}
+
+TEST_F(CoreExtTests, OnObjectWritesLedgerObject)
+{
+    auto const data = util::createObject();
+
+    EXPECT_CALL(*backend_, writeLedgerObject(auto{data.keyRaw}, kSEQ, auto{data.dataRaw}));
+
+    ext_.onObject(kSEQ, data);
+}
--- a/tests/unit/etlng/ext/NFTTests.cpp
+++ b/tests/unit/etlng/ext/NFTTests.cpp
@@ -0,0 +1,287 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2025, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include "etlng/Models.hpp"
+#include "etlng/impl/ext/NFT.hpp"
+#include "util/BinaryTestObject.hpp"
+#include "util/MockBackendTestFixture.hpp"
+#include "util/MockPrometheus.hpp"
+#include "util/TestObject.hpp"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <xrpl/protocol/TxFormats.h>
+
+#include <utility>
+#include <vector>
+
+using namespace etlng::impl;
+using namespace data;
+
+namespace {
+constinit auto const kSEQ = 123u;
+constinit auto const kLEDGER_HASH = "4BC50C9B0D8515D3EAAE1E74B29A95804346C491EE1A95BF25E4AAB854A6A652";
+
+constinit auto const kTXN_HEX2 =
+    "12001D230606B58324048A8B6F501C50E8EBCD412E6CF9D0C2EB6D38BDE1E1C83406AFCB45437DF39A8B0677A9487E501DA2A1BC9A62AAEB2A"
+    "2A70F895587A3FB752514AA03F8C6E7C84864653B8673E0368400000000000001E60134000000000001F09732103B8C234E0598BC26D8A3E1B"
+    "FF53EB252EC0F15EA6800E4D85AA5D7CD15D76B01E744730450221009C0AFF5F3298E10ABE42894717DA46B59529A366527AA5DFC1577ADEA9"
+    "B20FA70220494D1D9BFEF2AB09F4D6403AAC5B9DCC5B859DCEC1380C6D817A6EDFE7E68FD581141565EED165BA79999425204A8491C73B1301"
+    "E34FF9EA7D0F7872702E63616665202D2073616C65E1F1";
+
+constinit auto const kTXN_META2 =
+    "201C00000040F8E51100502505A59E11552ABC2FD74D879BE58489A588838AA2BA59E1E05A48A574226CD8B6CE77998971560B639A808E3B97"
+    "42A25334E5CF68EEDEDE52F54E50F4E63921C9F3C40588E426E6FAEC5A000827104B18F97F9209869C9E9CC33EC2AAE2864A69498F5B79952C"
+    "052AB2897542697066733A2F2F6261666B726569683673796D616974676D67616E6B67766B6B3568767A786C636463326D6876346E71673472"
+    "6E747037653769757469766C796275E1EC5A000827107B87E64C884BBFB60FDDC47DABE4D52E4AD1F0A5006B75170000007B752E516D526950"
+    "5679335464654A6170697974576B686141576B4D716D39335350696433587A524C564A437872537772E1EC5A000827107B87E64C884BBFB60F"
+    "DDC47DABE4D52E4AD1F0A50A85CBBC00000022752E516D596543706A427A7A5257516733527935455661725A4250316B79556A47625A7A4169"
+    "316B4C316E5255797131E1EC5A000827107B87E64C884BBFB60FDDC47DABE4D52E4AD1F0A5423F2594000001FA752E516D554C457664644634"
+    "5442427374455138484C66694867456B6A4465514D56676F39486A463476656752533277E1EC5A000827107B87E64C884BBFB60FDDC47DABE4"
+    "D52E4AD1F0A5608E298B000000EF752E516D4E6E56566F4250426755783848334641486F436162593647347577445758767738757455636976"
+    "73764D7142E1EC5A000827107B87E64C884BBFB60FDDC47DABE4D52E4AD1F0A57A9089B80000021E752E516D5275674657434B626443325646"
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+
+constinit auto const kHASH2 = "D7604B124D5D9C89EC1854A6CBD5A1FFD92502E945411B9C8DE397E7F19A74F8";
+
+auto
+createTestData()
+{
+    auto transactions = std::vector{
+        util::createTransaction(ripple::TxType::ttNFTOKEN_BURN),
+        util::createTransaction(ripple::TxType::ttNFTOKEN_BURN, kHASH2, kTXN_META2, kTXN_HEX2),
+        util::createTransaction(ripple::TxType::ttAMM_CREATE),    // not NFT - will be filtered
+        util::createTransaction(ripple::TxType::ttNFTOKEN_BURN),  // not unique - will be filtered
+    };
+
+    auto const header = createLedgerHeader(kLEDGER_HASH, kSEQ);
+    return etlng::model::LedgerData{
+        .transactions = std::move(transactions),
+        .objects = {},
+        .successors = {},
+        .edgeKeys = {},
+        .header = header,
+        .rawHeader = {},
+        .seq = kSEQ
+    };
+}
+
+}  // namespace
+
+struct NFTExtTests : util::prometheus::WithPrometheus, MockBackendTest {
+protected:
+    etlng::impl::NFTExt ext_{backend_};
+};
+
+TEST_F(NFTExtTests, OnLedgerDataFiltersAndWritesNFTs)
+{
+    auto const data = createTestData();
+
+    EXPECT_CALL(*backend_, writeNFTs).WillOnce([](auto const& nfts) {
+        EXPECT_EQ(nfts.size(), 2);  // AMM filtered out, two BURN txs are not unique
+    });
+    EXPECT_CALL(*backend_, writeNFTTransactions);
+
+    ext_.onLedgerData(data);
+}
+
+TEST_F(NFTExtTests, OnInitialDataFiltersAndWritesNFTs)
+{
+    auto const data = createTestData();
+
+    EXPECT_CALL(*backend_, writeNFTs).WillOnce([](auto const& nfts) {
+        EXPECT_EQ(nfts.size(), 2);  // AMM filtered out, two BURN txs are not unique
+    });
+    EXPECT_CALL(*backend_, writeNFTTransactions);
+
+    ext_.onInitialData(data);
+}
+
+TEST_F(NFTExtTests, OnInitialObjectExtractsAndWritesNFTData)
+{
+    auto const data = util::createObjectWithTwoNFTs();
+
+    EXPECT_CALL(*backend_, writeNFTs).WillOnce([](auto const& nfts) { EXPECT_EQ(nfts.size(), 2); });
+
+    ext_.onInitialObject(kSEQ, data);
+}
--- a/tests/unit/etlng/ext/SuccessorTests.cpp
+++ b/tests/unit/etlng/ext/SuccessorTests.cpp
@@ -0,0 +1,641 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2025, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include "data/DBHelpers.hpp"
+#include "data/Types.hpp"
+#include "etlng/Models.hpp"
+#include "etlng/impl/ext/Successor.hpp"
+#include "util/Assert.hpp"
+#include "util/BinaryTestObject.hpp"
+#include "util/MockAssert.hpp"
+#include "util/MockBackendTestFixture.hpp"
+#include "util/MockLedgerCache.hpp"
+#include "util/MockPrometheus.hpp"
+#include "util/StringUtils.hpp"
+#include "util/TestObject.hpp"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <xrpl/basics/StringUtilities.h>
+#include <xrpl/basics/base_uint.h>
+#include <xrpl/protocol/TxFormats.h>
+#include <xrpl/protocol/UintTypes.h>
+
+#include <algorithm>
+#include <iterator>
+#include <optional>
+#include <queue>
+#include <stdexcept>
+#include <string>
+#include <utility>
+#include <vector>
+
+using namespace etlng::impl;
+using namespace data;
+
+namespace {
+constinit auto const kSEQ = 123u;
+constinit auto const kLEDGER_HASH = "4BC50C9B0D8515D3EAAE1E74B29A95804346C491EE1A95BF25E4AAB854A6A652";
+
+auto
+createTestData(std::vector<etlng::model::Object> objects)
+{
+    auto transactions = std::vector{
+        util::createTransaction(ripple::TxType::ttNFTOKEN_BURN),
+        util::createTransaction(ripple::TxType::ttNFTOKEN_BURN),
+        util::createTransaction(ripple::TxType::ttNFTOKEN_CREATE_OFFER),
+    };
+
+    auto const header = createLedgerHeader(kLEDGER_HASH, kSEQ);
+    return etlng::model::LedgerData{
+        .transactions = std::move(transactions),
+        .objects = std::move(objects),
+        .successors = {},
+        .edgeKeys = {},
+        .header = header,
+        .rawHeader = {},
+        .seq = kSEQ
+    };
+}
+
+[[maybe_unused]] auto
+createInitialTestData(std::vector<ripple::uint256> edgeKeys)
+{
+    // initial data expects objects to be empty as well as non-empty edgeKeys
+    ASSERT(not edgeKeys.empty(), "Initial data requires edgeKeys");
+
+    auto ret = createTestData({});
+    ret.edgeKeys = std::make_optional<std::vector<std::string>>();
+    std::ranges::transform(edgeKeys, std::back_inserter(ret.edgeKeys.value()), &uint256ToString);
+
+    return ret;
+}
+
+}  // namespace
+
+struct SuccessorExtTests : util::prometheus::WithPrometheus, MockBackendTest {
+protected:
+    MockLedgerCache cache_;
+    etlng::impl::SuccessorExt ext_{backend_, cache_};
+};
+
+TEST_F(SuccessorExtTests, OnLedgerDataLogicErrorIfCacheIsNotFullButSuccessorsNotPresent)
+{
+    auto const data = createTestData({});
+
+    EXPECT_CALL(cache_, isFull()).WillRepeatedly(testing::Return(false));
+    EXPECT_CALL(cache_, latestLedgerSequence()).WillRepeatedly(testing::Return(kSEQ));
+
+    EXPECT_THROW(ext_.onLedgerData(data), std::logic_error);
+}
+
+TEST_F(SuccessorExtTests, OnLedgerDataLogicErrorIfCacheIsFullButLatestSeqDiffersAndSuccessorsNotPresent)
+{
+    auto const data = createTestData({});
+
+    EXPECT_CALL(cache_, isFull()).WillRepeatedly(testing::Return(true));
+    EXPECT_CALL(cache_, latestLedgerSequence()).WillRepeatedly(testing::Return(kSEQ - 1));
+
+    EXPECT_THROW(ext_.onLedgerData(data), std::logic_error);
+}
+
+TEST_F(SuccessorExtTests, OnLedgerDataWithDeletedObjectButWithoutCachedPredecessorAndSuccessorAndNoBookBase)
+{
+    using namespace etlng::model;
+
+    auto const objKey = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960D";
+    auto const deletedObj = util::createObject(Object::ModType::Deleted, objKey);
+    auto const data = createTestData({
+        deletedObj,
+        util::createObject(Object::ModType::Modified),
+    });
+
+    EXPECT_CALL(cache_, isFull()).WillRepeatedly(testing::Return(true));
+    EXPECT_CALL(cache_, latestLedgerSequence()).WillRepeatedly(testing::Return(kSEQ));
+
+    EXPECT_CALL(cache_, getPredecessor(deletedObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+    EXPECT_CALL(cache_, getSuccessor(deletedObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(data::kFIRST_KEY), kSEQ, uint256ToString(data::kLAST_KEY)));
+    EXPECT_CALL(cache_, getDeleted(deletedObj.key, kSEQ - 1)).WillRepeatedly(testing::Return(Blob{'0'}));
+
+    ext_.onLedgerData(data);
+}
+
+TEST_F(SuccessorExtTests, OnLedgerDataWithCreatedObjectButWithoutCachedPredecessorAndSuccessorAndNoBookBase)
+{
+    using namespace etlng::model;
+
+    auto const objKey = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960D";
+    auto const createdObj = util::createObject(Object::ModType::Created, objKey);
+    auto const data = createTestData({
+        createdObj,
+        util::createObject(Object::ModType::Modified),
+    });
+
+    EXPECT_CALL(cache_, isFull()).WillRepeatedly(testing::Return(true));
+    EXPECT_CALL(cache_, latestLedgerSequence()).WillRepeatedly(testing::Return(kSEQ));
+
+    EXPECT_CALL(cache_, getPredecessor(createdObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+    EXPECT_CALL(cache_, getSuccessor(createdObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(data::kFIRST_KEY), kSEQ, uint256ToString(createdObj.key)));
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(createdObj.key), kSEQ, uint256ToString(data::kLAST_KEY)));
+
+    ext_.onLedgerData(data);
+}
+
+TEST_F(SuccessorExtTests, OnLedgerDataWithCreatedObjectButWithoutCachedPredecessorAndSuccessorWithBookBase)
+{
+    using namespace etlng::model;
+
+    auto const objKey = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960D";
+    auto const createdObj = util::createObjectWithBookBase(Object::ModType::Created, objKey);
+    auto const data = createTestData({
+        createdObj,
+        util::createObject(Object::ModType::Modified),
+    });
+    auto const bookBase = getBookBase(createdObj.key);
+
+    EXPECT_CALL(cache_, isFull()).WillRepeatedly(testing::Return(true));
+    EXPECT_CALL(cache_, latestLedgerSequence()).WillRepeatedly(testing::Return(kSEQ));
+
+    EXPECT_CALL(cache_, getPredecessor(createdObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+    EXPECT_CALL(cache_, getSuccessor(createdObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(data::kFIRST_KEY), kSEQ, uint256ToString(createdObj.key)));
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(createdObj.key), kSEQ, uint256ToString(data::kLAST_KEY)));
+
+    EXPECT_CALL(cache_, get(createdObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+    EXPECT_CALL(cache_, getSuccessor(bookBase, kSEQ)).WillRepeatedly(testing::Return(LedgerObject{}));
+
+    ext_.onLedgerData(data);
+}
+
+TEST_F(
+    SuccessorExtTests,
+    OnLedgerDataWithCreatedObjectButWithoutCachedPredecessorAndSuccessorWithBookBaseAndMatchingSuccessorInCache
+)
+{
+    using namespace etlng::model;
+
+    auto const objKey = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960D";
+    auto const createdObj = util::createObjectWithBookBase(Object::ModType::Created, objKey);
+    auto const data = createTestData({
+        createdObj,
+        util::createObject(Object::ModType::Modified),
+    });
+    auto const bookBase = getBookBase(createdObj.key);
+
+    [[maybe_unused]] testing::InSequence inSeq;
+    EXPECT_CALL(cache_, isFull()).WillRepeatedly(testing::Return(true));
+    EXPECT_CALL(cache_, latestLedgerSequence()).WillRepeatedly(testing::Return(kSEQ));
+
+    EXPECT_CALL(cache_, getPredecessor(createdObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+    EXPECT_CALL(cache_, getSuccessor(createdObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(data::kFIRST_KEY), kSEQ, uint256ToString(createdObj.key)));
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(createdObj.key), kSEQ, uint256ToString(data::kLAST_KEY)));
+
+    EXPECT_CALL(cache_, get(createdObj.key, kSEQ)).WillRepeatedly(testing::Return(data::Blob{'0'}));
+    EXPECT_CALL(cache_, getSuccessor(bookBase, kSEQ))
+        .WillRepeatedly(testing::Return(LedgerObject{.key = createdObj.key, .blob = {}}));
+
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(bookBase), kSEQ, testing::_));
+
+    ext_.onLedgerData(data);
+}
+
+TEST_F(
+    SuccessorExtTests,
+    OnLedgerDataWithDeletedObjectButWithoutCachedPredecessorAndSuccessorWithBookBaseButNoCurrentObjAndNoSuccessorInCache
+)
+{
+    using namespace etlng::model;
+
+    auto const objKey = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960D";
+    auto const createdObj = util::createObjectWithBookBase(Object::ModType::Created, objKey);
+    auto const deletedObj = util::createObjectWithBookBase(Object::ModType::Deleted, objKey);
+    auto const data = createTestData({
+        deletedObj,
+        util::createObject(Object::ModType::Modified),
+    });
+    auto const bookBase = getBookBase(deletedObj.key);
+    auto const oldCachedObj = createdObj.data;
+
+    [[maybe_unused]] testing::InSequence inSeq;
+    EXPECT_CALL(cache_, isFull()).WillRepeatedly(testing::Return(true));
+    EXPECT_CALL(cache_, latestLedgerSequence()).WillRepeatedly(testing::Return(kSEQ));
+
+    EXPECT_CALL(cache_, getPredecessor(deletedObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+    EXPECT_CALL(cache_, getSuccessor(deletedObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(data::kFIRST_KEY), kSEQ, uint256ToString(data::kLAST_KEY)));
+    EXPECT_CALL(cache_, getDeleted(deletedObj.key, kSEQ - 1)).WillOnce(testing::Return(oldCachedObj));
+
+    EXPECT_CALL(cache_, get(deletedObj.key, kSEQ)).WillOnce(testing::Return(std::nullopt));
+    EXPECT_CALL(cache_, getSuccessor(bookBase, kSEQ)).WillOnce(testing::Return(std::nullopt));
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(bookBase), kSEQ, uint256ToString(data::kLAST_KEY)));
+
+    ext_.onLedgerData(data);
+}
+
+TEST_F(
+    SuccessorExtTests,
+    OnLedgerDataWithDeletedObjectButWithoutCachedPredecessorAndSuccessorWithBookBaseAndCurrentObjAndSuccessorInCache
+)
+{
+    using namespace etlng::model;
+
+    auto const objKey = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960D";
+    auto const createdObj = util::createObjectWithBookBase(Object::ModType::Created, objKey);
+    auto const deletedObj = util::createObjectWithBookBase(Object::ModType::Deleted, objKey);
+    auto const data = createTestData({
+        deletedObj,
+        util::createObject(Object::ModType::Modified),
+    });
+    auto const bookBase = getBookBase(deletedObj.key);
+    auto const oldCachedObj = createdObj.data;
+
+    [[maybe_unused]] testing::InSequence inSeq;
+    EXPECT_CALL(cache_, isFull()).WillRepeatedly(testing::Return(true));
+    EXPECT_CALL(cache_, latestLedgerSequence()).WillRepeatedly(testing::Return(kSEQ));
+
+    EXPECT_CALL(cache_, getPredecessor(deletedObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+    EXPECT_CALL(cache_, getSuccessor(deletedObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(data::kFIRST_KEY), kSEQ, uint256ToString(data::kLAST_KEY)));
+    EXPECT_CALL(cache_, getDeleted(deletedObj.key, kSEQ - 1)).WillOnce(testing::Return(oldCachedObj));
+
+    EXPECT_CALL(cache_, get(deletedObj.key, kSEQ)).WillOnce(testing::Return(data::Blob{'0'}));
+    EXPECT_CALL(cache_, getSuccessor(bookBase, kSEQ))
+        .WillRepeatedly(testing::Return(LedgerObject{.key = deletedObj.key, .blob = {}}));
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(bookBase), kSEQ, uint256ToString(deletedObj.key)));
+
+    ext_.onLedgerData(data);
+}
+
+TEST_F(SuccessorExtTests, OnLedgerDataWithDeletedObjectAndWithCachedPredecessorAndSuccessor)
+{
+    using namespace etlng::model;
+
+    auto const objKey = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960D";
+    auto const predKey =
+        binaryStringToUint256(hexStringToBinaryString("B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960C"
+        ));
+    auto const succKey =
+        binaryStringToUint256(hexStringToBinaryString("B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960E"
+        ));
+    auto const createdObj = util::createObject(Object::ModType::Created, objKey);
+    auto const data = createTestData({
+        createdObj,
+        util::createObject(Object::ModType::Modified),
+    });
+
+    EXPECT_CALL(cache_, isFull()).WillRepeatedly(testing::Return(true));
+    EXPECT_CALL(cache_, latestLedgerSequence()).WillRepeatedly(testing::Return(kSEQ));
+
+    EXPECT_CALL(cache_, getPredecessor(createdObj.key, kSEQ))
+        .WillOnce(testing::Return(data::LedgerObject{.key = predKey, .blob = {}}));
+    EXPECT_CALL(cache_, getSuccessor(createdObj.key, kSEQ))
+        .WillOnce(testing::Return(data::LedgerObject{.key = succKey, .blob = {}}));
+
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(predKey), kSEQ, uint256ToString(createdObj.key)));
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(createdObj.key), kSEQ, uint256ToString(succKey)));
+
+    ext_.onLedgerData(data);
+}
+
+TEST_F(SuccessorExtTests, OnLedgerDataWithCreatedObjectAndIncludedSuccessors)
+{
+    using namespace etlng::model;
+
+    auto const objKey = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960D";
+    auto const createdObj = util::createObject(Object::ModType::Created, objKey);
+    auto data = createTestData({
+        createdObj,
+        util::createObject(Object::ModType::Modified),
+    });
+    auto const succ = util::createSuccessor();
+    data.successors = {succ, succ, succ};
+
+    EXPECT_CALL(*backend_, writeSuccessor(auto{succ.bookBase}, kSEQ, auto{succ.firstBook}))
+        .Times(data.successors->size());
+
+    EXPECT_CALL(*backend_, writeSuccessor(auto{createdObj.predecessor}, kSEQ, auto{createdObj.keyRaw}));
+    EXPECT_CALL(*backend_, writeSuccessor(auto{createdObj.keyRaw}, kSEQ, auto{createdObj.successor}));
+
+    ext_.onLedgerData(data);
+}
+
+TEST_F(SuccessorExtTests, OnLedgerDataWithDeletedObjectAndIncludedSuccessorsWithoutFirstBook)
+{
+    using namespace etlng::model;
+
+    auto const objKey = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960D";
+    auto const deletedObj = util::createObject(Object::ModType::Deleted, objKey);
+    auto data = createTestData({
+        deletedObj,
+        util::createObject(Object::ModType::Modified),
+    });
+    auto succ = util::createSuccessor();
+    succ.firstBook = {};  // empty will be transformed into kLAST_KEY
+    data.successors = {succ, succ};
+
+    EXPECT_CALL(*backend_, writeSuccessor(auto{succ.bookBase}, kSEQ, uint256ToString(data::kLAST_KEY)))
+        .Times(data.successors->size());
+
+    EXPECT_CALL(*backend_, writeSuccessor(auto{deletedObj.predecessor}, kSEQ, auto{deletedObj.successor}));
+
+    ext_.onLedgerData(data);
+}
+
+TEST_F(SuccessorExtTests, OnInitialDataWithSuccessorsButNotBookDirAndNoSuccessorsForEdgeKeys)
+{
+    using namespace etlng::model;
+
+    auto const firstKey = ripple::uint256("B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960C");
+    auto const secondKey = ripple::uint256("B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960E");
+    auto const data = createInitialTestData({firstKey, secondKey});
+
+    auto successorChain = std::queue<ripple::uint256>();
+    successorChain.push(firstKey);
+    successorChain.push(secondKey);
+
+    [[maybe_unused]] testing::Sequence inSeq;
+    EXPECT_CALL(cache_, isFull()).WillOnce(testing::Return(true));
+
+    EXPECT_CALL(cache_, getSuccessor(testing::_, kSEQ))
+        .Times(3)
+        .InSequence(inSeq)
+        .WillRepeatedly([&](auto&&, auto&&) -> std::optional<data::LedgerObject> {
+            if (successorChain.empty())
+                return std::nullopt;
+
+            auto v = successorChain.front();
+            successorChain.pop();
+            return data::LedgerObject{.key = v, .blob = {'0'}};
+        });
+
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(data::kFIRST_KEY), kSEQ, uint256ToString(firstKey)));
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(secondKey), kSEQ, uint256ToString(data::kLAST_KEY)));
+
+    for (auto const& key : data.edgeKeys.value()) {
+        EXPECT_CALL(cache_, getSuccessor(*ripple::uint256::fromVoidChecked(key), kSEQ))
+            .InSequence(inSeq)
+            .WillOnce(testing::Return(std::nullopt));
+    }
+
+    ext_.onInitialData(data);
+}
+
+TEST_F(SuccessorExtTests, OnInitialDataWithSuccessorsButNotBookDirAndSuccessorsForEdgeKeys)
+{
+    using namespace etlng::model;
+
+    auto const firstKey = ripple::uint256("B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960C");
+    auto const secondKey = ripple::uint256("B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960E");
+    auto const data = createInitialTestData({firstKey, secondKey});
+
+    auto successorChain = std::queue<ripple::uint256>();
+    successorChain.push(firstKey);
+    successorChain.push(secondKey);
+
+    [[maybe_unused]] testing::Sequence inSeq;
+    EXPECT_CALL(cache_, isFull()).WillOnce(testing::Return(true));
+
+    EXPECT_CALL(cache_, getSuccessor(testing::_, kSEQ))
+        .Times(3)
+        .InSequence(inSeq)
+        .WillRepeatedly([&](auto&&, auto&&) -> std::optional<data::LedgerObject> {
+            if (successorChain.empty())
+                return std::nullopt;
+
+            auto v = successorChain.front();
+            successorChain.pop();
+            return data::LedgerObject{.key = v, .blob = {'0'}};
+        });
+
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(data::kFIRST_KEY), kSEQ, uint256ToString(firstKey)));
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(secondKey), kSEQ, uint256ToString(data::kLAST_KEY)));
+
+    for (auto const& key : data.edgeKeys.value()) {
+        EXPECT_CALL(cache_, getSuccessor(*ripple::uint256::fromVoidChecked(key), kSEQ))
+            .InSequence(inSeq)
+            .WillOnce(testing::Return(data::LedgerObject{.key = firstKey, .blob = {}}));
+        EXPECT_CALL(*backend_, writeSuccessor(auto{key}, kSEQ, uint256ToString(firstKey)));
+    }
+
+    ext_.onInitialData(data);
+}
+
+TEST_F(SuccessorExtTests, OnInitialDataWithSuccessorsAndBookDirAndSuccessorsForEdgeKeys)
+{
+    using namespace etlng::model;
+
+    auto const firstKey = ripple::uint256("B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960C");
+    auto const secondKey = ripple::uint256("B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960E");
+    auto const data = createInitialTestData({firstKey, secondKey});
+
+    auto successorChain = std::queue<ripple::uint256>();
+    successorChain.push(firstKey);
+    successorChain.push(secondKey);
+
+    auto const bookBaseObj = util::createObjectWithBookBase(Object::ModType::Created);
+    auto const bookBase = getBookBase(bookBaseObj.key);
+
+    [[maybe_unused]] testing::Sequence inSeq;
+    EXPECT_CALL(cache_, isFull()).WillOnce(testing::Return(true));
+
+    EXPECT_CALL(cache_, getSuccessor(testing::_, kSEQ))
+        .Times(3)
+        .InSequence(inSeq)
+        .WillRepeatedly([&](auto&&, auto&&) -> std::optional<data::LedgerObject> {
+            if (successorChain.empty())
+                return std::nullopt;
+
+            auto v = successorChain.front();
+            successorChain.pop();
+            return data::LedgerObject{.key = v, .blob = bookBaseObj.data};
+        });
+
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(data::kFIRST_KEY), kSEQ, uint256ToString(firstKey)));
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(secondKey), kSEQ, uint256ToString(data::kLAST_KEY)));
+
+    EXPECT_CALL(cache_, get(bookBase, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+    EXPECT_CALL(cache_, getSuccessor(bookBase, kSEQ))
+        .WillRepeatedly(testing::Return(data::LedgerObject{.key = firstKey, .blob = data::Blob{'1'}}));
+    EXPECT_CALL(
+        *backend_, writeSuccessor(uint256ToString(bookBase), kSEQ, testing::_)
+    );  // Called once because firstKey returned repeatedly above
+
+    for (auto const& key : data.edgeKeys.value()) {
+        EXPECT_CALL(cache_, getSuccessor(*ripple::uint256::fromVoidChecked(key), kSEQ))
+            .InSequence(inSeq)
+            .WillOnce(testing::Return(data::LedgerObject{.key = firstKey, .blob = {'1'}}));
+        EXPECT_CALL(*backend_, writeSuccessor(auto{key}, kSEQ, uint256ToString(firstKey))).InSequence(inSeq);
+    }
+
+    ext_.onInitialData(data);
+}
+
+TEST_F(SuccessorExtTests, OnInitialObjectsWithEmptyLastKey)
+{
+    using namespace etlng::model;
+
+    auto const lastKey = std::string{};
+    auto const data = std::vector{
+        util::createObject(
+            Object::ModType::Created, "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960E"
+        ),
+        util::createObject(
+            Object::ModType::Created, "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960F"
+        ),
+        util::createObject(
+            Object::ModType::Created, "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E89610"
+        ),
+    };
+
+    std::string lk = lastKey;
+    for (auto const& obj : data) {
+        if (not lk.empty())
+            EXPECT_CALL(*backend_, writeSuccessor(std::move(lk), kSEQ, uint256ToString(obj.key)));
+        lk = uint256ToString(obj.key);
+    }
+
+    ext_.onInitialObjects(kSEQ, data, lastKey);
+}
+
+TEST_F(SuccessorExtTests, OnInitialObjectsWithNonEmptyLastKey)
+{
+    using namespace etlng::model;
+
+    auto const lastKey =
+        uint256ToString(ripple::uint256("B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960D"));
+    auto const data = std::vector{
+        util::createObject(
+            Object::ModType::Created, "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960E"
+        ),
+        util::createObject(
+            Object::ModType::Created, "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960F"
+        ),
+        util::createObject(
+            Object::ModType::Created, "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E89610"
+        ),
+    };
+
+    std::string lk = lastKey;
+    for (auto const& obj : data) {
+        EXPECT_CALL(*backend_, writeSuccessor(std::move(lk), kSEQ, uint256ToString(obj.key)));
+        lk = uint256ToString(obj.key);
+    }
+
+    ext_.onInitialObjects(kSEQ, data, lastKey);
+}
+
+struct SuccessorExtAssertTests : common::util::WithMockAssert, SuccessorExtTests {};
+
+TEST_F(SuccessorExtAssertTests, OnLedgerDataWithDeletedObjectAssertsIfGetDeletedIsNotInCache)
+{
+    using namespace etlng::model;
+
+    auto const objKey = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960D";
+    auto const deletedObj = util::createObject(Object::ModType::Deleted, objKey);
+    auto const data = createTestData({
+        deletedObj,
+        util::createObject(Object::ModType::Modified),
+    });
+
+    EXPECT_CALL(cache_, isFull()).WillRepeatedly(testing::Return(true));
+    EXPECT_CALL(cache_, latestLedgerSequence()).WillRepeatedly(testing::Return(kSEQ));
+
+    EXPECT_CALL(cache_, getPredecessor(deletedObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+    EXPECT_CALL(cache_, getSuccessor(deletedObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(data::kFIRST_KEY), kSEQ, uint256ToString(data::kLAST_KEY)));
+    EXPECT_CALL(cache_, getDeleted(deletedObj.key, kSEQ - 1)).WillRepeatedly(testing::Return(std::nullopt));
+
+    EXPECT_CLIO_ASSERT_FAIL({ ext_.onLedgerData(data); });
+}
+
+TEST_F(
+    SuccessorExtAssertTests,
+    OnLedgerDataWithCreatedObjectButWithoutCachedPredecessorAndSuccessorWithBookBaseAndBookSuccessorNotInCache
+)
+{
+    using namespace etlng::model;
+
+    auto const objKey = "B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960D";
+    auto const createdObj = util::createObjectWithBookBase(Object::ModType::Created, objKey);
+    auto const data = createTestData({
+        createdObj,
+        util::createObject(Object::ModType::Modified),
+    });
+    auto const bookBase = getBookBase(createdObj.key);
+
+    EXPECT_CALL(cache_, isFull()).WillRepeatedly(testing::Return(true));
+    EXPECT_CALL(cache_, latestLedgerSequence()).WillRepeatedly(testing::Return(kSEQ));
+
+    EXPECT_CALL(cache_, getPredecessor(createdObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+    EXPECT_CALL(cache_, getSuccessor(createdObj.key, kSEQ)).WillRepeatedly(testing::Return(std::nullopt));
+
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(data::kFIRST_KEY), kSEQ, uint256ToString(createdObj.key)));
+    EXPECT_CALL(*backend_, writeSuccessor(uint256ToString(createdObj.key), kSEQ, uint256ToString(data::kLAST_KEY)));
+
+    EXPECT_CALL(cache_, get(createdObj.key, kSEQ)).WillOnce(testing::Return(data::Blob{'0'}));
+    EXPECT_CALL(cache_, getSuccessor(bookBase, kSEQ)).WillOnce(testing::Return(std::nullopt));
+
+    EXPECT_CLIO_ASSERT_FAIL({ ext_.onLedgerData(data); });
+}
+
+TEST_F(SuccessorExtAssertTests, OnInitialDataNotIsFull)
+{
+    using namespace etlng::model;
+
+    auto const data = createTestData({
+        util::createObject(Object::ModType::Modified),
+        util::createObject(Object::ModType::Created),
+    });
+
+    EXPECT_CALL(cache_, isFull()).WillOnce(testing::Return(false));
+    EXPECT_CLIO_ASSERT_FAIL({ ext_.onInitialData(data); });
+}
+
+TEST_F(SuccessorExtAssertTests, OnInitialDataIsFullButNoEdgeKeys)
+{
+    using namespace etlng::model;
+
+    auto data = createTestData({});
+
+    EXPECT_CALL(cache_, isFull()).WillOnce(testing::Return(true));
+    EXPECT_CLIO_ASSERT_FAIL({ ext_.onInitialData(data); });
+}
+
+TEST_F(SuccessorExtAssertTests, OnInitialDataIsFullWithEdgeKeysButHasObjects)
+{
+    using namespace etlng::model;
+
+    auto const firstKey = ripple::uint256("B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960C");
+    auto const secondKey = ripple::uint256("B00AA769C00726371689ED66A7CF57C2502F1BF4BDFF2ACADF67A2A7B5E8960E");
+    auto data = createInitialTestData({firstKey, secondKey});
+    data.objects = {util::createObject()};
+
+    EXPECT_CALL(cache_, isFull()).WillOnce(testing::Return(true));
+    EXPECT_CLIO_ASSERT_FAIL({ ext_.onInitialData(data); });
+}
--- a/tests/unit/rpc/handlers/AccountCurrenciesTests.cpp
+++ b/tests/unit/rpc/handlers/AccountCurrenciesTests.cpp
@@ -41,9 +41,9 @@

 using namespace rpc;
 using namespace data;
+using namespace testing;

 namespace json = boost::json;
-using namespace testing;

 namespace {