diff --git a/include/bitcoin/database/error.hpp b/include/bitcoin/database/error.hpp
index c8f52f92..8d3caceb 100644
--- a/include/bitcoin/database/error.hpp
+++ b/include/bitcoin/database/error.hpp
@@ -141,6 +141,7 @@ enum error_t : uint8_t
     /// txs archive
     txs_header,
     txs_empty,
+    txs_height,
     txs_confirm,
     txs_txs_put
 };
diff --git a/include/bitcoin/database/impl/query/archive_write.ipp b/include/bitcoin/database/impl/query/archive_write.ipp
index a4bbb6a1..ed54581e 100644
--- a/include/bitcoin/database/impl/query/archive_write.ipp
+++ b/include/bitcoin/database/impl/query/archive_write.ipp
@@ -65,11 +65,10 @@ bool CLASS::set(const transaction& tx) NOEXCEPT
 }
 
 TEMPLATE
-bool CLASS::set(const block& block, bool strong, bool bypass,
-    size_t height) NOEXCEPT
+bool CLASS::set(const block& block, bool strong, bool bypass) NOEXCEPT
 {
     // This sets only the txs of a block with header/context already archived.
-    return !set_code(block, strong, bypass, height);
+    return !set_code(block, strong, bypass);
 }
 
 // set transaction
@@ -350,27 +349,30 @@ code CLASS::set_code(header_link& out_fk, const block& block,
 // releases all memory for parts of itself, due to the custom allocator.
 
 TEMPLATE
-code CLASS::set_code(const block& block, bool strong, bool bypass,
-    size_t height) NOEXCEPT
+code CLASS::set_code(const block& block, bool strong, bool bypass) NOEXCEPT
 {
     header_link unused{};
-    return set_code(unused, block, strong, bypass, height);
+    return set_code(unused, block, strong, bypass);
 }
 
 TEMPLATE
 code CLASS::set_code(header_link& out_fk, const block& block, bool strong,
-    bool bypass, size_t height) NOEXCEPT
+    bool bypass) NOEXCEPT
 {
     out_fk = to_header(block.get_hash());
     if (out_fk.is_terminal())
         return error::txs_header;
 
+    size_t height{};
+    if (!get_height(height, out_fk))
+        return error::txs_height;
+
     return set_code(block, out_fk, strong, bypass, height);
 }
 
 TEMPLATE
 code CLASS::set_code(const block& block, const header_link& key,
-    bool strong, bool bypass, size_t /* height */) NOEXCEPT
+    bool strong, bool bypass, size_t height) NOEXCEPT
 {
     using namespace system;
     if (key.is_terminal())
@@ -392,16 +394,10 @@ code CLASS::set_code(const block& block, const header_link& key,
             return ec;
 
     using bytes = linkage<schema::size>::integer;
+    auto interval = get_interval(key, height);
     const auto size = block.serialized_size(true);
     const auto wire = possible_narrow_cast<bytes>(size);
 
-    // TODO: compute and set interval hash for interval blocks as configured.
-    // TODO: create query to walk header.parent across full interval to collect
-    // TODO: merkle leaves and compute intermediate merkle root. This requires
-    // TODO: header.parent link traversal only, with read of hash for each. The
-    // TODO: full interval of hashes (e.g. 2048) is preallocated to a vector.
-    std::optional<hash_digest> interval{};
-
     // ========================================================================
     const auto scope = store_.get_transactor();
     constexpr auto positive = true;
diff --git a/include/bitcoin/database/impl/query/optional.ipp b/include/bitcoin/database/impl/query/optional.ipp
index e06b8981..bb2ee8b0 100644
--- a/include/bitcoin/database/impl/query/optional.ipp
+++ b/include/bitcoin/database/impl/query/optional.ipp
@@ -259,6 +259,41 @@ code CLASS::get_confirmed_balance(std::atomic_bool& cancel, uint64_t& balance,
     return error::success;
 }
 
+TEMPLATE
+std::optional<hash_digest> CLASS::get_interval(header_link link,
+    size_t height) const NOEXCEPT
+{
+    // Interval is enabled by address table.
+    if (!address_enabled())
+        return {};
+
+    // Interval is the merkle root that spans 2^depth block hashes.
+    const auto span = system::power2(store_.interval_depth());
+
+    // power2() overflow returns zero.
+    if (is_zero(span))
+        return {};
+
+    // One is a functional but undesirable case.
+    if (is_one(span))
+        return get_header_key(link);
+
+    // Interval ends at nth block where n is a multiple of span.
+    if (!system::is_multiple(add1(height), span))
+        return {};
+
+    // Generate the leaf nodes for the span.
+    hashes leaves(span);
+    for (auto& leaf: std::views::reverse(leaves))
+    {
+        leaf = get_header_key(link);
+        link = to_parent(link);
+    }
+
+    // Generate the interval (merkle root) for the span ending on link header.
+    return system::merkle_root(std::move(leaves));
+}
+
 ////TEMPLATE
 ////bool CLASS::set_address_output(const output& output,
 ////    const output_link& link) NOEXCEPT
diff --git a/include/bitcoin/database/impl/store.ipp b/include/bitcoin/database/impl/store.ipp
index 0ff7eaf2..c87a9b7a 100644
--- a/include/bitcoin/database/impl/store.ipp
+++ b/include/bitcoin/database/impl/store.ipp
@@ -232,6 +232,12 @@ bool CLASS::turbo() const NOEXCEPT
     return configuration_.turbo;
 }
 
+TEMPLATE
+uint8_t CLASS::interval_depth() const NOEXCEPT
+{
+    return configuration_.interval_depth;
+}
+
 TEMPLATE
 code CLASS::create(const event_handler& handler) NOEXCEPT
 {
diff --git a/include/bitcoin/database/query.hpp b/include/bitcoin/database/query.hpp
index aafe1cde..4e6680ff 100644
--- a/include/bitcoin/database/query.hpp
+++ b/include/bitcoin/database/query.hpp
@@ -21,6 +21,7 @@
 
 #include <atomic>
 #include <mutex>
+#include <optional>
 #include <utility>
 #include <bitcoin/system.hpp>
 #include <bitcoin/database/define.hpp>
@@ -412,8 +413,7 @@ class query
     bool set(const block& block, const context& ctx,
         bool milestone, bool strong) NOEXCEPT;
     bool set(const transaction& tx) NOEXCEPT;
-    bool set(const block& block, bool strong, bool bypass,
-        size_t height) NOEXCEPT;
+    bool set(const block& block, bool strong, bool bypass) NOEXCEPT;
 
     /// Set transaction.
     code set_code(const transaction& tx) NOEXCEPT;
@@ -439,10 +439,9 @@ class query
         const chain_context& ctx, bool milestone, bool strong) NOEXCEPT;
 
     /// Set block.txs (headers-first).
-    code set_code(const block& block, bool strong, bool bypass,
-        size_t height) NOEXCEPT;
+    code set_code(const block& block, bool strong, bool bypass) NOEXCEPT;
     code set_code(header_link& out_fk, const block& block, bool strong,
-        bool bypass, size_t height) NOEXCEPT;
+        bool bypass) NOEXCEPT;
     code set_code(const block& block, const header_link& key, bool strong,
         bool bypass, size_t height) NOEXCEPT;
 
@@ -569,7 +568,12 @@ class query
     code get_minimum_unspent_outputs(std::atomic_bool& cancel, outpoints& out,
         const hash_digest& key, uint64_t value, bool turbo=false) const NOEXCEPT;
     code get_confirmed_balance(std::atomic_bool& cancel,
-        uint64_t& balance, const hash_digest& key, bool turbo=false) const NOEXCEPT;
+        uint64_t& balance, const hash_digest& key,
+        bool turbo=false) const NOEXCEPT;
+
+    /// No value if header is not at configured interval.
+    std::optional<hash_digest> get_interval(header_link header,
+        size_t height) const NOEXCEPT;
 
     bool is_filtered_body(const header_link& link) const NOEXCEPT;
     bool get_filter_body(filter& out, const header_link& link) const NOEXCEPT;
diff --git a/include/bitcoin/database/settings.hpp b/include/bitcoin/database/settings.hpp
index ab606f67..d1161e8a 100644
--- a/include/bitcoin/database/settings.hpp
+++ b/include/bitcoin/database/settings.hpp
@@ -37,7 +37,15 @@ struct BCD_API settings
     settings(system::chain::selection context) NOEXCEPT;
 
     /// Properties.
+    /// -----------------------------------------------------------------------
+
+    /// Enable concurrency in individual client-server queries.
     bool turbo;
+
+    /// Depth of electrum merkle tree interval caching.
+    uint8_t interval_depth;
+
+    /// Path to the database directory.
     std::filesystem::path path;
 
     /// Archives.
diff --git a/include/bitcoin/database/store.hpp b/include/bitcoin/database/store.hpp
index 2dfe0586..d7e3c7d9 100644
--- a/include/bitcoin/database/store.hpp
+++ b/include/bitcoin/database/store.hpp
@@ -60,6 +60,9 @@ class store
     /// Allow full throttle concurrent query execution (may use 100% CPU).
     bool turbo() const NOEXCEPT;
 
+    /// Depth of electrum merkle tree interval caching.
+    uint8_t interval_depth() const NOEXCEPT;
+
     /// Methods.
     /// -----------------------------------------------------------------------
 
diff --git a/include/bitcoin/database/tables/archives/txs.hpp b/include/bitcoin/database/tables/archives/txs.hpp
index 834367e3..5ba9e41b 100644
--- a/include/bitcoin/database/tables/archives/txs.hpp
+++ b/include/bitcoin/database/tables/archives/txs.hpp
@@ -53,7 +53,7 @@ struct txs
         return set_right(wire, offset, interval);
     }
 
-    // Intervals are set only if non-zero in database.interval.
+    // Intervals are optional based on store configuration.
     struct slab
       : public schema::txs
     {
@@ -121,7 +121,8 @@ struct txs
         inline link count() const NOEXCEPT
         {
             return system::possible_narrow_cast<link::integer>(ct::size +
-                bytes::size + tx::size * number);
+                bytes::size + tx::size * number +
+                (interval.has_value() ? schema::hash : zero));
         }
 
         inline bool to_data(finalizer& sink) const NOEXCEPT
diff --git a/src/error.cpp b/src/error.cpp
index a7877eb0..19916be2 100644
--- a/src/error.cpp
+++ b/src/error.cpp
@@ -134,6 +134,7 @@ DEFINE_ERROR_T_MESSAGE_MAP(error)
     // txs archive
     { txs_header, "txs_header" },
     { txs_empty, "txs_empty" },
+    { txs_height, "txs_height" },
     { txs_confirm, "txs_confirm" },
     { txs_txs_put, "txs_txs_put" }
 };
diff --git a/src/settings.cpp b/src/settings.cpp
index c075b275..4e33615c 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -28,6 +28,7 @@ using namespace bc::system;
 
 settings::settings() NOEXCEPT
   : turbo{ false },
+    interval_depth{ max_uint8 },
     path{ "bitcoin" },
 
     // Archives.
diff --git a/test/error.cpp b/test/error.cpp
index 824c0de1..7c608d03 100644
--- a/test/error.cpp
+++ b/test/error.cpp
@@ -686,6 +686,15 @@ BOOST_AUTO_TEST_CASE(error_t__code__txs_empty__true_exected_message)
     BOOST_REQUIRE_EQUAL(ec.message(), "txs_empty");
 }
 
+BOOST_AUTO_TEST_CASE(error_t__code__txs_height__true_exected_message)
+{
+    constexpr auto value = error::txs_height;
+    const auto ec = code(value);
+    BOOST_REQUIRE(ec);
+    BOOST_REQUIRE(ec == value);
+    BOOST_REQUIRE_EQUAL(ec.message(), "txs_height");
+}
+
 BOOST_AUTO_TEST_CASE(error_t__code__txs_confirm__true_exected_message)
 {
     constexpr auto value = error::txs_confirm;
diff --git a/test/query/archive_write.cpp b/test/query/archive_write.cpp
index 5842dcc6..5fa4a9cb 100644
--- a/test/query/archive_write.cpp
+++ b/test/query/archive_write.cpp
@@ -705,7 +705,7 @@ BOOST_AUTO_TEST_CASE(query_archive_write__set_block_txs__get_block__expected)
     BOOST_REQUIRE(!query.is_block(test::genesis.hash()));
     BOOST_REQUIRE(query.set(test::genesis.header(), test::context, milestone));
     BOOST_REQUIRE(!query.is_associated(0));
-    BOOST_REQUIRE(query.set(test::genesis, false, false, zero));
+    BOOST_REQUIRE(query.set(test::genesis, false, false));
     BOOST_REQUIRE(query.is_block(test::genesis.hash()));
     BOOST_REQUIRE(query.is_associated(0));
 
diff --git a/test/query/initialize.cpp b/test/query/initialize.cpp
index c0285abe..3d1264d7 100644
--- a/test/query/initialize.cpp
+++ b/test/query/initialize.cpp
@@ -415,17 +415,17 @@ BOOST_AUTO_TEST_CASE(query_initialize__get_unassociated_above__gapped_candidate_
     BOOST_REQUIRE_EQUAL(unassociated3.size(), 0u);
 
     // There are two unassociated blocks above block 1 (new fork point).
-    BOOST_REQUIRE(query.set(test::block1, false, false, zero));
+    BOOST_REQUIRE(query.set(test::block1, false, false));
     BOOST_REQUIRE(query.push_confirmed(query.to_header(test::block1.hash()), false));
     BOOST_REQUIRE_EQUAL(query.get_all_unassociated().size(), 2u);
 
     // There is one unassociated block above block 2 (new fork point).
-    BOOST_REQUIRE(query.set(test::block2, false, false, zero));
+    BOOST_REQUIRE(query.set(test::block2, false, false));
     BOOST_REQUIRE(query.push_confirmed(query.to_header(test::block2.hash()), false));
     BOOST_REQUIRE_EQUAL(query.get_all_unassociated().size(), 1u);
 
     // There are no unassociated blocks above block 3 (new fork point).
-    BOOST_REQUIRE(query.set(test::block3, false, false, zero));
+    BOOST_REQUIRE(query.set(test::block3, false, false));
     BOOST_REQUIRE(query.push_confirmed(query.to_header(test::block3.hash()), false));
     BOOST_REQUIRE_EQUAL(query.get_all_unassociated().size(), 0u);
 }
@@ -482,7 +482,7 @@ BOOST_AUTO_TEST_CASE(query_initialize__get_unassociated_count_above__gapped_cand
     BOOST_REQUIRE_EQUAL(query.get_unassociated_count_above(3, 1), 0u);
 
     // There is one unassociated block at block 2.
-    BOOST_REQUIRE(query.set(test::block3, false, false, zero));             // associated
+    BOOST_REQUIRE(query.set(test::block3, false, false));             // associated
     BOOST_REQUIRE_EQUAL(query.get_unassociated_count(), 1u);
     BOOST_REQUIRE_EQUAL(query.get_unassociated_count_above(0), 1u);
     BOOST_REQUIRE_EQUAL(query.get_unassociated_count_above(1), 1u);
@@ -490,7 +490,7 @@ BOOST_AUTO_TEST_CASE(query_initialize__get_unassociated_count_above__gapped_cand
     BOOST_REQUIRE_EQUAL(query.get_unassociated_count_above(3), 0u);
 
     // There are no unassociated blocks.
-    BOOST_REQUIRE(query.set(test::block2, false, false, zero));             // associated
+    BOOST_REQUIRE(query.set(test::block2, false, false));             // associated
     BOOST_REQUIRE_EQUAL(query.get_unassociated_count(), 0u);
     BOOST_REQUIRE_EQUAL(query.get_unassociated_count_above(0), 0u);
     BOOST_REQUIRE_EQUAL(query.get_unassociated_count_above(1), 0u);
diff --git a/test/query/optional.cpp b/test/query/optional.cpp
index abdb68b5..30004858 100644
--- a/test/query/optional.cpp
+++ b/test/query/optional.cpp
@@ -227,6 +227,94 @@ BOOST_AUTO_TEST_CASE(query_optional__get_confirmed_balance__genesis__expected)
     BOOST_REQUIRE_EQUAL(out, 5000000000u);
 }
 
+// Merkle root of test blocks [0..1]
+constexpr auto root01 = system::base16_hash("abdc2227d02d114b77be15085c1257709252a7a103f9ac0ab3c85d67e12bc0b8");
+
+// Merkle root of test blocks [2..4]
+constexpr auto root02 = system::base16_hash("f2a2a2907abb326726a2d6500fe494f63772a941b414236c302e920bc1aa9caf");
+
+// Merkle root of test blocks [0..4]
+constexpr auto root04 = system::sha256::double_hash(root01, root02);
+
+BOOST_AUTO_TEST_CASE(query_optional__get_interval__depth_0__block_hash)
+{
+    settings settings{};
+    settings.interval_depth = 0;
+    settings.path = TEST_DIRECTORY;
+    test::chunk_store store{ settings };
+    test::query_accessor query{ store };
+    BOOST_REQUIRE_EQUAL(store.create(events_handler), error::success);
+    BOOST_REQUIRE(query.initialize(test::genesis));
+    BOOST_REQUIRE(query.set(test::block1, context{ 0, 1, 0 }, false, false));
+    BOOST_REQUIRE(query.set(test::block2, context{ 0, 2, 0 }, false, false));
+    BOOST_REQUIRE(query.set(test::block3, context{ 0, 3, 0 }, false, false));
+
+    const auto header0 = query.to_header(test::genesis.hash());
+    const auto header1 = query.to_header(test::block1.hash());
+    const auto header2 = query.to_header(test::block2.hash());
+    const auto header3 = query.to_header(test::block3.hash());
+    BOOST_REQUIRE(!header0.is_terminal());
+    BOOST_REQUIRE(!header1.is_terminal());
+    BOOST_REQUIRE(!header2.is_terminal());
+    BOOST_REQUIRE(!header3.is_terminal());
+    BOOST_REQUIRE(query.get_interval(header0, 0).has_value());
+    BOOST_REQUIRE(query.get_interval(header1, 1).has_value());
+    BOOST_REQUIRE(query.get_interval(header2, 2).has_value());
+    BOOST_REQUIRE(query.get_interval(header3, 3).has_value());
+    BOOST_REQUIRE_EQUAL(query.get_interval(header0, 0).value(), test::genesis.hash());
+    BOOST_REQUIRE_EQUAL(query.get_interval(header1, 1).value(), test::block1.hash());
+    BOOST_REQUIRE_EQUAL(query.get_interval(header2, 2).value(), test::block2.hash());
+    BOOST_REQUIRE_EQUAL(query.get_interval(header3, 3).value(), test::block3.hash());
+}
+
+BOOST_AUTO_TEST_CASE(query_optional__get_interval__depth_1__expected)
+{
+    settings settings{};
+    settings.interval_depth = 1;
+    settings.path = TEST_DIRECTORY;
+    test::chunk_store store{ settings };
+    test::query_accessor query{ store };
+    BOOST_REQUIRE_EQUAL(store.create(events_handler), error::success);
+    BOOST_REQUIRE(query.initialize(test::genesis));
+    BOOST_REQUIRE(query.set(test::block1, context{ 0, 1, 0 }, false, false));
+    BOOST_REQUIRE(query.set(test::block2, context{ 0, 2, 0 }, false, false));
+    BOOST_REQUIRE(query.set(test::block3, context{ 0, 3, 0 }, false, false));
+
+    const auto header0 = query.to_header(test::genesis.hash());
+    const auto header1 = query.to_header(test::block1.hash());
+    const auto header2 = query.to_header(test::block2.hash());
+    const auto header3 = query.to_header(test::block3.hash());
+    BOOST_REQUIRE(!header0.is_terminal());
+    BOOST_REQUIRE(!header1.is_terminal());
+    BOOST_REQUIRE(!header2.is_terminal());
+    BOOST_REQUIRE(!header3.is_terminal());
+    BOOST_REQUIRE(!query.get_interval(header0, 0).has_value());
+    BOOST_REQUIRE( query.get_interval(header1, 1).has_value());
+    BOOST_REQUIRE(!query.get_interval(header2, 2).has_value());
+    BOOST_REQUIRE( query.get_interval(header3, 3).has_value());
+    BOOST_REQUIRE_EQUAL(query.get_interval(header1, 1).value(), root01);
+    BOOST_REQUIRE_EQUAL(query.get_interval(header3, 3).value(), root02);
+}
+
+BOOST_AUTO_TEST_CASE(query_optional__get_interval__depth_2__expected)
+{
+    settings settings{};
+    settings.interval_depth = 2;
+    settings.path = TEST_DIRECTORY;
+    test::chunk_store store{ settings };
+    test::query_accessor query{ store };
+    BOOST_REQUIRE_EQUAL(store.create(events_handler), error::success);
+    BOOST_REQUIRE(query.initialize(test::genesis));
+    BOOST_REQUIRE(query.set(test::block1, context{ 0, 1, 0 }, false, false));
+    BOOST_REQUIRE(query.set(test::block2, context{ 0, 2, 0 }, false, false));
+    BOOST_REQUIRE(query.set(test::block3, context{ 0, 3, 0 }, false, false));
+
+    const auto header3 = query.to_header(test::block3.hash());
+    BOOST_REQUIRE(!header3.is_terminal());
+    BOOST_REQUIRE(query.get_interval(header3, 3).has_value());
+    BOOST_REQUIRE_EQUAL(query.get_interval(header3, 3).value(), root04);
+}
+
 ////BOOST_AUTO_TEST_CASE(query_optional__set_filter__get_filter_and_head__expected)
 ////{
 ////    const auto& filter_head0 = system::null_hash;
diff --git a/test/settings.cpp b/test/settings.cpp
index f8beee0a..3767e3c6 100644
--- a/test/settings.cpp
+++ b/test/settings.cpp
@@ -24,6 +24,7 @@ BOOST_AUTO_TEST_CASE(settings__construct__default__expected)
 {
     database::settings configuration;
     BOOST_REQUIRE_EQUAL(configuration.turbo, false);
+    BOOST_REQUIRE_EQUAL(configuration.interval_depth, 255u);
     BOOST_REQUIRE_EQUAL(configuration.path, "bitcoin");
 
     // Archives.