diff --git a/include/bitcoin/database/impl/query/confirm.ipp b/include/bitcoin/database/impl/query/confirm.ipp
index d1d3e886..e73c4d14 100644
--- a/include/bitcoin/database/impl/query/confirm.ipp
+++ b/include/bitcoin/database/impl/query/confirm.ipp
@@ -407,6 +407,26 @@ code CLASS::block_confirmable(const header_link& link) const NOEXCEPT
     return ec;
 }
 
+// Used by node for ASIO concurrency by tx.
+TEMPLATE
+code CLASS::tx_confirmable(const tx_link& link,
+    const context& ctx) const NOEXCEPT
+{
+    code ec{};
+    const auto set = to_spend_set(link);
+    for (const auto& spend: set.spends)
+    {
+        if ((ec = unspendable_prevout(spend.point_fk, spend.sequence,
+            set.version, ctx)))
+            return ec;
+
+        if (is_spent_prevout(spend.prevout(), link))
+            return error::confirmed_double_spend;
+    }
+
+    return error::success;
+}
+
 #if defined(UNDEFINED)
 
 // protected
@@ -426,25 +446,6 @@ spend_sets CLASS::to_spend_sets(
     return sets;
 }
 
-TEMPLATE
-code CLASS::tx_confirmable(const tx_link& link,
-    const context& ctx) const NOEXCEPT
-{
-    code ec{};
-    const auto set = to_spend_set(link);
-    for (const auto& spend : set.spends)
-    {
-        if ((ec = unspendable_prevout(spend.point_fk, spend.sequence,
-            set.version, ctx)))
-            return ec;
-
-        if (is_spent_prevout(spend.prevout(), link))
-            return error::confirmed_double_spend;
-    }
-
-    return error::success;
-}
-
 // split(0) 403 secs for 400k-410k
 TEMPLATE
 code CLASS::block_confirmable(const header_link& link) const NOEXCEPT
diff --git a/include/bitcoin/database/query.hpp b/include/bitcoin/database/query.hpp
index 7c4e717c..95f9fa5b 100644
--- a/include/bitcoin/database/query.hpp
+++ b/include/bitcoin/database/query.hpp
@@ -490,9 +490,7 @@ class query
     bool set_strong_parallel(const header_link& link) NOEXCEPT;
     bool set_unstrong_parallel(const header_link& link) NOEXCEPT;
     code block_confirmable(const header_link& link) const NOEXCEPT;
-#if defined(UNDEFINED)
     code tx_confirmable(const tx_link& link, const context& ctx) const NOEXCEPT;
-#endif
     code unspent_duplicates(const tx_link& coinbase,
         const context& ctx) const NOEXCEPT;