diff --git a/include/bitcoin/database/impl/query/archive_write.ipp b/include/bitcoin/database/impl/query/archive_write.ipp
index f5aaeafd..15a0041a 100644
--- a/include/bitcoin/database/impl/query/archive_write.ipp
+++ b/include/bitcoin/database/impl/query/archive_write.ipp
@@ -164,10 +164,10 @@ code CLASS::set_code(const tx_link& tx_fk, const transaction& tx,
         if (!store_.point.expand(ins_fk + inputs))
             return error::tx_point_allocate;
 
-        // If dirty we must guard against duplicates.
-        // Dirty doesn't hold up in the case of an invalidated block, as that
-        // may result in a duplicated tx. So dirty should be false in the case
-        // of a non-bypass (valid) block.
+        // If dirty we must guard against duplicates. Dirty is caused by disk,
+        // full, disorganized or reorganized block, and tx pooling. It is set
+        // to true at runtime by any of these and in case of duplicate table
+        // non-empty at store startup. disorg/reorg indicated by candidate pop.
         // Must be set after tx.set and before tx.commit, since searchable and
         // produces association to tx.link, and is also an integral part of tx.
         if (store_.is_dirty() || !bypass)
diff --git a/include/bitcoin/database/impl/query/height.ipp b/include/bitcoin/database/impl/query/height.ipp
index 765735cd..b91bdb28 100644
--- a/include/bitcoin/database/impl/query/height.ipp
+++ b/include/bitcoin/database/impl/query/height.ipp
@@ -343,6 +343,9 @@ bool CLASS::pop_candidate() NOEXCEPT
     // ========================================================================
     const auto scope = store_.get_transactor();
 
+    // Candidate pop implies reorg or disorg, which implies future duplicates.
+    store_.set_dirty();
+
     ///////////////////////////////////////////////////////////////////////////
     std::unique_lock interlock{ candidate_reorganization_mutex_ };
     return store_.candidate.truncate(top);
diff --git a/include/bitcoin/database/impl/store.ipp b/include/bitcoin/database/impl/store.ipp
index 115c70b1..bae4a4fd 100644
--- a/include/bitcoin/database/impl/store.ipp
+++ b/include/bitcoin/database/impl/store.ipp
@@ -19,6 +19,7 @@
 #ifndef LIBBITCOIN_DATABASE_STORE_IPP
 #define LIBBITCOIN_DATABASE_STORE_IPP
 
+#include <atomic>
 #include <chrono>
 #include <unordered_map>
 #include <bitcoin/database/boost.hpp>
@@ -561,7 +562,7 @@ code CLASS::reload(const event_handler& handler) NOEXCEPT
             {
                 handler(event_t::load_file, table);
                 ec = storage.reload();
-                this->dirty_ = true;
+                this->dirty_.store(true, std::memory_order_relaxed);
             }
         }
     };
@@ -774,7 +775,8 @@ code CLASS::open_load(const event_handler& handler) NOEXCEPT
     load(ec, filter_tx_body_, table_t::filter_tx_body);
 
     // create, open, and restore each invoke open_load.
-    dirty_ = header_body_.size() > schema::header::minrow;
+    const auto dirty = header_body_.size() > schema::header::minrow;
+    dirty_.store(dirty, std::memory_order_relaxed);
     return ec;
 }
 
@@ -1164,7 +1166,13 @@ const typename CLASS::transactor CLASS::get_transactor() NOEXCEPT
 TEMPLATE
 bool CLASS::is_dirty() const NOEXCEPT
 {
-    return dirty_;
+    return dirty_.load(std::memory_order_relaxed);
+}
+
+TEMPLATE
+void CLASS::set_dirty() NOEXCEPT
+{
+    return dirty_.store(true, std::memory_order_relaxed);
 }
 
 TEMPLATE
diff --git a/include/bitcoin/database/store.hpp b/include/bitcoin/database/store.hpp
index 1ed1d719..38f10519 100644
--- a/include/bitcoin/database/store.hpp
+++ b/include/bitcoin/database/store.hpp
@@ -19,6 +19,7 @@
 #ifndef LIBBITCOIN_DATABASE_STORE_HPP
 #define LIBBITCOIN_DATABASE_STORE_HPP
 
+#include <atomic>
 #include <filesystem>
 #include <shared_mutex>
 #include <unordered_map>
@@ -95,6 +96,7 @@ class store
 
     /// Determine if the store is non-empty/initialized.
     bool is_dirty() const NOEXCEPT;
+    void set_dirty() NOEXCEPT;
 
     /// Get first fault code or error::success.
     code get_fault() const NOEXCEPT;
@@ -235,7 +237,9 @@ class store
     flush_lock flush_lock_;
     interprocess_lock process_lock_;
     std::shared_timed_mutex transactor_mutex_{};
-    bool dirty_{ true };
+
+    // This is thread safe.
+    std::atomic_bool dirty_{ true };
 
 private:
     using path = std::filesystem::path;
diff --git a/test/store.cpp b/test/store.cpp
index a7eb11ee..765cdfcb 100644
--- a/test/store.cpp
+++ b/test/store.cpp
@@ -52,7 +52,7 @@ BOOST_AUTO_TEST_CASE(store__is_dirty__uninitialized__true)
     BOOST_REQUIRE(instance.is_dirty());
 }
 
-BOOST_AUTO_TEST_CASE(store__is_dirty__initialized__true)
+BOOST_AUTO_TEST_CASE(store__is_dirty__initialized___false)
 {
     settings configuration{};
     configuration.path = TEST_DIRECTORY;
@@ -64,6 +64,20 @@ BOOST_AUTO_TEST_CASE(store__is_dirty__initialized__true)
     BOOST_REQUIRE(!instance.close(events));
 }
 
+BOOST_AUTO_TEST_CASE(store__set_dirty__initialized__is_dirty)
+{
+    settings configuration{};
+    configuration.path = TEST_DIRECTORY;
+    store<map> instance{ configuration };
+    query<store<map>> query_{ instance };
+    BOOST_REQUIRE(!instance.create(events));
+    BOOST_REQUIRE(query_.initialize(test::genesis));
+    BOOST_REQUIRE(!instance.is_dirty());
+    instance.set_dirty();
+    BOOST_REQUIRE(instance.is_dirty());
+    BOOST_REQUIRE(!instance.close(events));
+}
+
 BOOST_AUTO_TEST_CASE(store__is_dirty__open__false)
 {
     settings configuration{};