>Вторник, 20 октября 2020, 15:38 +03:00 от Nikita Pettik <korablev@tarantool.org>:
> 
>On 20 Oct 15:34, Ilya Kosarev wrote:
>>
>> Hi,
>>  
>> Thanks for the patch!
>>  
>> LGTM, i checked for the number of compilers that if with the templated
>> agrument is being processed at the compile time so that there are no jumps
>> in asm code.
>>  
>> What i think is needed is the enum like the following:
>> enum {
>>         NOT_HINTED = 0 ,
>>         HINTED = 1 ,
>> };
>
>I like this way. Btw why not using just boolean type?
I think there was an idea to implement more than one type of hints.
Also it doesn’t really matter as far as we have the proper constants.
>  
>> to avoid using <0> & <1>. If needed i can push such patch to the branch.
>> >Понедельник, 19 октября 2020, 12:52 +03:00 от Aleksandr Lyapunov < alyapunov@tarantool.org >:
>> > 
>> >Since 9fba29abb4e05babb9b23b4413bd8083f0fba933 (memtx: introduce tuple
>> >compare hint) memtx tree key data (indexes) started to contain extra 8
>> >bytes as a hint. Now it is optional and can be turned off in an index
>> >options with "hint = false" entry.
>> >
>> >Closes #4927
>> >
>> >@TarantoolBot document
>> >Title: memtx: optional tuple compare hints
>> >Update the documentation for an index creation to reflect that there is
>> >now an option to turn off hints for the index.
>> >---
>> > src/box/index_def.c | 2 +
>> > src/box/index_def.h | 6 +
>> > src/box/lua/schema.lua | 53 ++++
>> > src/box/lua/space.cc | 7 +
>> > src/box/memtx_engine.c | 2 +
>> > src/box/memtx_tree.cc | 599 ++++++++++++++++++++++++------------
>> > src/lib/salad/bps_tree.h | 19 ++
>> > test/box/alter.result | 103 ++++++-
>> > test/box/alter.test.lua | 34 ++
>> > test/box/errinj.result | 3 +-
>> > test/box/tree_pk.result | 314 +++++++++++++++++++
>> > test/box/tree_pk.test.lua | 115 +++++++
>> > test/box/tree_pk_multipart.result | 153 +++++++++
>> > test/box/tree_pk_multipart.test.lua | 64 ++++
>> > 14 files changed, 1269 insertions(+), 205 deletions(-)
>> >
>> >diff --git a/src/box/index_def.c b/src/box/index_def.c
>> >index 9802961..79394b8 100644
>> >--- a/src/box/index_def.c
>> >+++ b/src/box/index_def.c
>> >@@ -51,6 +51,7 @@ const struct index_opts index_opts_default = {
>> >  /* .lsn = */ 0,
>> >  /* .stat = */ NULL,
>> >  /* .func = */ 0,
>> >+ /* .hint = */ true,
>> > };
>> > 
>> > const struct opt_def index_opts_reg[] = {
>> >@@ -66,6 +67,7 @@ const struct opt_def index_opts_reg[] = {
>> >  OPT_DEF("lsn", OPT_INT64, struct index_opts, lsn),
>> >  OPT_DEF("func", OPT_UINT32, struct index_opts, func_id),
>> >  OPT_DEF_LEGACY("sql"),
>> >+ OPT_DEF("hint", OPT_BOOL, struct index_opts, hint),
>> >  OPT_END,
>> > };
>> > 
>> >diff --git a/src/box/index_def.h b/src/box/index_def.h
>> >index d928b23..2180a69 100644
>> >--- a/src/box/index_def.h
>> >+++ b/src/box/index_def.h
>> >@@ -165,6 +165,10 @@ struct index_opts {
>> >  struct index_stat *stat;
>> >  /** Identifier of the functional index function. */
>> >  uint32_t func_id;
>> >+ /**
>> >+ * Use hint optimization for tree index.
>> >+ */
>> >+ bool hint;
>> > };
>> > 
>> > extern const struct index_opts index_opts_default;
>> >@@ -211,6 +215,8 @@ index_opts_cmp(const struct index_opts *o1, const struct index_opts *o2)
>> >  return o1->bloom_fpr < o2->bloom_fpr ? -1 : 1;
>> >  if (o1->func_id != o2->func_id)
>> >  return o1->func_id - o2->func_id;
>> >+ if (o1->hint != o2->hint)
>> >+ return o1->hint - o2->hint;
>> >  return 0;
>> > }
>> > 
>> >diff --git a/src/box/lua/schema.lua b/src/box/lua/schema.lua
>> >index 1131af7..9cc1289 100644
>> >--- a/src/box/lua/schema.lua
>> >+++ b/src/box/lua/schema.lua
>> >@@ -1000,8 +1000,31 @@ local index_options = {
>> >     page_size = 'number',
>> >     bloom_fpr = 'number',
>> >     func = 'number, string',
>> >+ hint = 'boolean',
>> > }
>> > 
>> >+local function jsonpaths_from_idx_parts(parts)
>> >+ local paths = {}
>> >+
>> >+ for _, part in pairs(parts) do
>> >+ if type(part.path) == 'string' then
>> >+ table.insert(paths, part.path)
>> >+ end
>> >+ end
>> >+
>> >+ return paths
>> >+end
>> >+
>> >+local function is_multikey_index(parts)
>> >+ for _, path in pairs(jsonpaths_from_idx_parts(parts)) do
>> >+ if path:find('[*]', 1, true) then
>> >+ return true
>> >+ end
>> >+ end
>> >+
>> >+ return false
>> >+end
>> >+
>> > --
>> > -- check_param_table() template for alter index,
>> > -- includes all index options.
>> >@@ -1076,6 +1099,15 @@ box.schema.index.create = function(space_id, name, options)
>> >         options_defaults = {}
>> >     end
>> >     options = update_param_table(options, options_defaults)
>> >+ if options.hint and
>> >+ (options.type ~= 'tree' or box.space[space_id].engine ~= 'memtx') then
>> >+ box.error(box.error.MODIFY_INDEX, name, space.name,
>> >+ "hint is only reasonable with memtx tree index")
>> >+ end
>> >+ if options.hint and options.func then
>> >+ box.error(box.error.MODIFY_INDEX, name, space.name,
>> >+ "functional index can't use hints")
>> >+ end
>> > 
>> >     local _index = box.space[box.schema.INDEX_ID]
>> >     local _vindex = box.space[box.schema.VINDEX_ID]
>> >@@ -1115,6 +1147,7 @@ box.schema.index.create = function(space_id, name, options)
>> >             run_size_ratio = options.run_size_ratio,
>> >             bloom_fpr = options.bloom_fpr,
>> >             func = options.func,
>> >+ hint = options.hint,
>> >     }
>> >     local field_type_aliases = {
>> >         num = 'unsigned'; -- Deprecated since 1.7.2
>> >@@ -1135,6 +1168,10 @@ box.schema.index.create = function(space_id, name, options)
>> >     if parts_can_be_simplified then
>> >         parts = simplify_index_parts(parts)
>> >     end
>> >+ if options.hint and is_multikey_index(parts) then
>> >+ box.error(box.error.MODIFY_INDEX, name, space.name,
>> >+ "multikey index can't use hints")
>> >+ end
>> >     if index_opts.func ~= nil and type(index_opts.func) == 'string' then
>> >         index_opts.func = func_id_by_name(index_opts.func)
>> >     end
>> >@@ -1253,6 +1290,17 @@ box.schema.index.alter = function(space_id, index_id, options)
>> >             index_opts[k] = options[k]
>> >         end
>> >     end
>> >+ if options.hint and
>> >+ (options.type ~= 'tree' or box.space[space_id].engine ~= 'memtx') then
>> >+ box.error(box.error.MODIFY_INDEX, space.index[index_id].name,
>> >+ space.name,
>> >+ "hint is only reasonable with memtx tree index")
>> >+ end
>> >+ if options.hint and options.func then
>> >+ box.error(box.error.MODIFY_INDEX, space.index[index_id].name,
>> >+ space.name,
>> >+ "functional index can't use hints")
>> >+ end
>> >     if options.parts then
>> >         local parts_can_be_simplified
>> >         parts, parts_can_be_simplified =
>> >@@ -1262,6 +1310,11 @@ box.schema.index.alter = function(space_id, index_id, options)
>> >             parts = simplify_index_parts(parts)
>> >         end
>> >     end
>> >+ if options.hint and is_multikey_index(parts) then
>> >+ box.error(box.error.MODIFY_INDEX, space.index[index_id].name,
>> >+ space.name,
>> >+ "multikey index can't use hints")
>> >+ end
>> >     if index_opts.func ~= nil and type(index_opts.func) == 'string' then
>> >         index_opts.func = func_id_by_name(index_opts.func)
>> >     end
>> >diff --git a/src/box/lua/space.cc b/src/box/lua/space.cc
>> >index 177c588..1ea993c 100644
>> >--- a/src/box/lua/space.cc
>> >+++ b/src/box/lua/space.cc
>> >@@ -344,6 +344,13 @@ lbox_fillspace(struct lua_State *L, struct space *space, int i)
>> >  lua_pushnumber(L, index_opts->dimension);
>> >  lua_setfield(L, -2, "dimension");
>> >  }
>> >+ if (space_is_memtx(space) && index_def->type == TREE) {
>> >+ lua_pushboolean(L, index_opts->hint);
>> >+ lua_setfield(L, -2, "hint");
>> >+ } else {
>> >+ lua_pushnil(L);
>> >+ lua_setfield(L, -2, "hint");
>> >+ }
>> > 
>> >  if (index_opts->func_id > 0) {
>> >  lua_pushstring(L, "func");
>> >diff --git a/src/box/memtx_engine.c b/src/box/memtx_engine.c
>> >index  8147557 ..43000ba 100644
>> >--- a/src/box/memtx_engine.c
>> >+++ b/src/box/memtx_engine.c
>> >@@ -1398,6 +1398,8 @@ memtx_index_def_change_requires_rebuild(struct index *index,
>> >  return true;
>> >  if (old_def->opts.func_id != new_def->opts.func_id)
>> >  return true;
>> >+ if (old_def->opts.hint != new_def->opts.hint)
>> >+ return true;
>> > 
>> >  const struct key_def *old_cmp_def, *new_cmp_def;
>> >  if (index_depends_on_pk(index)) {
>> >diff --git a/src/box/memtx_tree.cc b/src/box/memtx_tree.cc
>> >index d3b993b..17d58c5 100644
>> >--- a/src/box/memtx_tree.cc
>> >+++ b/src/box/memtx_tree.cc
>> >@@ -45,23 +45,51 @@
>> > /**
>> >  * Struct that is used as a key in BPS tree definition.
>> >  */
>> >-struct memtx_tree_key_data {
>> >+struct memtx_tree_key_data_common {
>> >  /** Sequence of msgpacked search fields. */
>> >  const char *key;
>> >  /** Number of msgpacked search fields. */
>> >  uint32_t part_count;
>> >+};
>> >+
>> >+template <int USE_HINT>
>> >+struct memtx_tree_key_data;
>> >+
>> >+template <>
>> >+struct memtx_tree_key_data<0> : memtx_tree_key_data_common {
>> >+ static constexpr hint_t hint = HINT_NONE;
>> >+ void set_hint(hint_t) { assert(false); }
>> >+};
>> >+
>> >+template <>
>> >+struct memtx_tree_key_data<1> : memtx_tree_key_data_common {
>> >  /** Comparison hint, see tuple_hint(). */
>> >  hint_t hint;
>> >+ void set_hint(hint_t h) { hint = h; }
>> > };
>> > 
>> > /**
>> >  * Struct that is used as a elem in BPS tree definition.
>> >  */
>> >-struct memtx_tree_data {
>> >+struct memtx_tree_data_common {
>> >  /* Tuple that this node is represents. */
>> >  struct tuple *tuple;
>> >+};
>> >+
>> >+template <int USE_HINT>
>> >+struct memtx_tree_data;
>> >+
>> >+template <>
>> >+struct memtx_tree_data<0> : memtx_tree_data_common {
>> >+ static constexpr hint_t hint = HINT_NONE;
>> >+ void set_hint(hint_t) { assert(false); }
>> >+};
>> >+
>> >+template <>
>> >+struct memtx_tree_data<1> : memtx_tree_data<0> {
>> >  /** Comparison hint, see key_hint(). */
>> >  hint_t hint;
>> >+ void set_hint(hint_t h) { hint = h; }
>> > };
>> > 
>> > /**
>> >@@ -73,8 +101,8 @@ struct memtx_tree_data {
>> >  * @retval false - Otherwise.
>> >  */
>> > static bool
>> >-memtx_tree_data_is_equal(const struct memtx_tree_data *a,
>> >- const struct memtx_tree_data *b)
>> >+memtx_tree_data_is_equal(const struct memtx_tree_data_common *a,
>> >+ const struct memtx_tree_data_common *b)
>> > {
>> >  return a->tuple == b->tuple;
>> > }
>> >@@ -89,12 +117,28 @@ memtx_tree_data_is_equal(const struct memtx_tree_data *a,
>> >  (b)->part_count, (b)->hint, arg)
>> > #define BPS_TREE_IS_IDENTICAL(a, b) memtx_tree_data_is_equal(&a, &b)
>> > #define BPS_TREE_NO_DEBUG 1
>> >-#define bps_tree_elem_t struct memtx_tree_data
>> >-#define bps_tree_key_t struct memtx_tree_key_data *
>> > #define bps_tree_arg_t struct key_def *
>> > 
>> >+#define BPS_TREE_NAMESPACE NS_NO_HINT
>> >+#define bps_tree_elem_t struct memtx_tree_data<0>
>> >+#define bps_tree_key_t struct memtx_tree_key_data<0> *
>> >+
>> > #include "salad/bps_tree.h"
>> > 
>> >+#undef BPS_TREE_NAMESPACE
>> >+#undef bps_tree_elem_t
>> >+#undef bps_tree_key_t
>> >+
>> >+#define BPS_TREE_NAMESPACE NS_USE_HINT
>> >+#define bps_tree_elem_t struct memtx_tree_data<1>
>> >+#define bps_tree_key_t struct memtx_tree_key_data<1> *
>> >+
>> >+#include "salad/bps_tree.h"
>> >+
>> >+#undef BPS_TREE_NAMESPACE
>> >+#undef bps_tree_elem_t
>> >+#undef bps_tree_key_t
>> >+
>> > #undef BPS_TREE_NAME
>> > #undef BPS_TREE_BLOCK_SIZE
>> > #undef BPS_TREE_EXTENT_SIZE
>> >@@ -102,66 +146,119 @@ memtx_tree_data_is_equal(const struct memtx_tree_data *a,
>> > #undef BPS_TREE_COMPARE_KEY
>> > #undef BPS_TREE_IS_IDENTICAL
>> > #undef BPS_TREE_NO_DEBUG
>> >-#undef bps_tree_elem_t
>> >-#undef bps_tree_key_t
>> > #undef bps_tree_arg_t
>> > 
>> >+using namespace NS_NO_HINT;
>> >+using namespace NS_USE_HINT;
>> >+
>> >+template <int USE_HINT>
>> >+struct memtx_tree_selector;
>> >+
>> >+template <>
>> >+struct memtx_tree_selector<0> : NS_NO_HINT::memtx_tree {};
>> >+
>> >+template <>
>> >+struct memtx_tree_selector<1> : NS_USE_HINT::memtx_tree {};
>> >+
>> >+template <int USE_HINT>
>> >+using memtx_tree_t = struct memtx_tree_selector<USE_HINT>;
>> >+
>> >+template <int USE_HINT>
>> >+struct memtx_tree_iterator_selector;
>> >+
>> >+template <>
>> >+struct memtx_tree_iterator_selector<0> {
>> >+ using type = NS_NO_HINT::memtx_tree_iterator;
>> >+};
>> >+
>> >+template <>
>> >+struct memtx_tree_iterator_selector<1> {
>> >+ using type = NS_USE_HINT::memtx_tree_iterator;
>> >+};
>> >+
>> >+template <int USE_HINT>
>> >+using memtx_tree_iterator_t = typename memtx_tree_iterator_selector<USE_HINT>::type;
>> >+
>> >+static void
>> >+invalidate_tree_iterator(NS_NO_HINT::memtx_tree_iterator *itr)
>> >+{
>> >+ *itr = NS_NO_HINT::memtx_tree_invalid_iterator();
>> >+}
>> >+
>> >+static void
>> >+invalidate_tree_iterator(NS_USE_HINT::memtx_tree_iterator *itr)
>> >+{
>> >+ *itr = NS_USE_HINT::memtx_tree_invalid_iterator();
>> >+}
>> >+
>> >+template <int USE_HINT>
>> > struct memtx_tree_index {
>> >  struct index base;
>> >- struct memtx_tree tree;
>> >- struct memtx_tree_data *build_array;
>> >+ memtx_tree_t<USE_HINT> tree;
>> >+ struct memtx_tree_data<USE_HINT> *build_array;
>> >  size_t build_array_size, build_array_alloc_size;
>> >  struct memtx_gc_task gc_task;
>> >- struct memtx_tree_iterator gc_iterator;
>> >+ memtx_tree_iterator_t<USE_HINT> gc_iterator;
>> > };
>> > 
>> > /* {{{ Utilities. *************************************************/
>> > 
>> >+template <class TREE>
>> > static inline struct key_def *
>> >-memtx_tree_cmp_def(struct memtx_tree *tree)
>> >+memtx_tree_cmp_def(TREE *tree)
>> > {
>> >  return tree->arg;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static int
>> > memtx_tree_qcompare(const void* a, const void *b, void *c)
>> > {
>> >- const struct memtx_tree_data *data_a = (struct memtx_tree_data *)a;
>> >- const struct memtx_tree_data *data_b = (struct memtx_tree_data *)b;
>> >+ const struct memtx_tree_data<USE_HINT> *data_a =
>> >+ (struct memtx_tree_data<USE_HINT> *)a;
>> >+ const struct memtx_tree_data<USE_HINT> *data_b =
>> >+ (struct memtx_tree_data<USE_HINT> *)b;
>> >  struct key_def *key_def = (struct key_def *)c;
>> >  return tuple_compare(data_a->tuple, data_a->hint, data_b->tuple,
>> >  data_b->hint, key_def);
>> > }
>> > 
>> > /* {{{ MemtxTree Iterators ****************************************/
>> >+template <int USE_HINT>
>> > struct tree_iterator {
>> >  struct iterator base;
>> >- struct memtx_tree_iterator tree_iterator;
>> >+ memtx_tree_iterator_t<USE_HINT> tree_iterator;
>> >  enum iterator_type type;
>> >- struct memtx_tree_key_data key_data;
>> >- struct memtx_tree_data current;
>> >+ struct memtx_tree_key_data<USE_HINT> key_data;
>> >+ struct memtx_tree_data<USE_HINT> current;
>> >  /** Memory pool the iterator was allocated from. */
>> >  struct mempool *pool;
>> > };
>> > 
>> >-static_assert(sizeof(struct tree_iterator) <= MEMTX_ITERATOR_SIZE,
>> >- "sizeof(struct tree_iterator) must be less than or equal "
>> >+static_assert(sizeof(struct tree_iterator<0>) <= MEMTX_ITERATOR_SIZE,
>> >+ "sizeof(struct tree_iterator<0>) must be less than or equal "
>> >+ "to MEMTX_ITERATOR_SIZE");
>> >+static_assert(sizeof(struct tree_iterator<1>) <= MEMTX_ITERATOR_SIZE,
>> >+ "sizeof(struct tree_iterator<1>) must be less than or equal "
>> >  "to MEMTX_ITERATOR_SIZE");
>> > 
>> >+template <int USE_HINT>
>> > static void
>> > tree_iterator_free(struct iterator *iterator);
>> > 
>> >-static inline struct tree_iterator *
>> >-tree_iterator(struct iterator *it)
>> >+template <int USE_HINT>
>> >+static inline struct tree_iterator<USE_HINT> *
>> >+get_tree_iterator(struct iterator *it)
>> > {
>> >- assert(it->free == tree_iterator_free);
>> >- return (struct tree_iterator *) it;
>> >+ assert(it->free == &tree_iterator_free<USE_HINT>);
>> >+ return (struct tree_iterator<USE_HINT> *) it;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static void
>> > tree_iterator_free(struct iterator *iterator)
>> > {
>> >- struct tree_iterator *it = tree_iterator(iterator);
>> >+ struct tree_iterator<USE_HINT> *it = get_tree_iterator<USE_HINT>(iterator);
>> >  struct tuple *tuple = it->current.tuple;
>> >  if (tuple != NULL)
>> >  tuple_unref(tuple);
>> >@@ -176,14 +273,15 @@ tree_iterator_dummie(struct iterator *iterator, struct tuple **ret)
>> >  return 0;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static int
>> > tree_iterator_next_base(struct iterator *iterator, struct tuple **ret)
>> > {
>> >- struct memtx_tree_index *index =
>> >- (struct memtx_tree_index *)iterator->index;
>> >- struct tree_iterator *it = tree_iterator(iterator);
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)iterator->index;
>> >+ struct tree_iterator<USE_HINT> *it = get_tree_iterator<USE_HINT>(iterator);
>> >  assert(it->current.tuple != NULL);
>> >- struct memtx_tree_data *check =
>> >+ struct memtx_tree_data<USE_HINT> *check =
>> >  memtx_tree_iterator_get_elem(&index->tree, &it->tree_iterator);
>> >  if (check == NULL || !memtx_tree_data_is_equal(check, &it->current)) {
>> >  it->tree_iterator = memtx_tree_upper_bound_elem(&index->tree,
>> >@@ -192,7 +290,7 @@ tree_iterator_next_base(struct iterator *iterator, struct tuple **ret)
>> >  memtx_tree_iterator_next(&index->tree, &it->tree_iterator);
>> >  }
>> >  tuple_unref(it->current.tuple);
>> >- struct memtx_tree_data *res =
>> >+ struct memtx_tree_data<USE_HINT> *res =
>> >  memtx_tree_iterator_get_elem(&index->tree, &it->tree_iterator);
>> >  if (res == NULL) {
>> >  iterator->next = tree_iterator_dummie;
>> >@@ -206,14 +304,15 @@ tree_iterator_next_base(struct iterator *iterator, struct tuple **ret)
>> >  return 0;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static int
>> > tree_iterator_prev_base(struct iterator *iterator, struct tuple **ret)
>> > {
>> >- struct memtx_tree_index *index =
>> >- (struct memtx_tree_index *)iterator->index;
>> >- struct tree_iterator *it = tree_iterator(iterator);
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)iterator->index;
>> >+ struct tree_iterator<USE_HINT> *it = get_tree_iterator<USE_HINT>(iterator);
>> >  assert(it->current.tuple != NULL);
>> >- struct memtx_tree_data *check =
>> >+ struct memtx_tree_data<USE_HINT> *check =
>> >  memtx_tree_iterator_get_elem(&index->tree, &it->tree_iterator);
>> >  if (check == NULL || !memtx_tree_data_is_equal(check, &it->current)) {
>> >  it->tree_iterator = memtx_tree_lower_bound_elem(&index->tree,
>> >@@ -221,7 +320,7 @@ tree_iterator_prev_base(struct iterator *iterator, struct tuple **ret)
>> >  }
>> >  memtx_tree_iterator_prev(&index->tree, &it->tree_iterator);
>> >  tuple_unref(it->current.tuple);
>> >- struct memtx_tree_data *res =
>> >+ struct memtx_tree_data<USE_HINT> *res =
>> >  memtx_tree_iterator_get_elem(&index->tree, &it->tree_iterator);
>> >  if (!res) {
>> >  iterator->next = tree_iterator_dummie;
>> >@@ -235,14 +334,15 @@ tree_iterator_prev_base(struct iterator *iterator, struct tuple **ret)
>> >  return 0;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static int
>> > tree_iterator_next_equal_base(struct iterator *iterator, struct tuple **ret)
>> > {
>> >- struct memtx_tree_index *index =
>> >- (struct memtx_tree_index *)iterator->index;
>> >- struct tree_iterator *it = tree_iterator(iterator);
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)iterator->index;
>> >+ struct tree_iterator<USE_HINT> *it = get_tree_iterator<USE_HINT>(iterator);
>> >  assert(it->current.tuple != NULL);
>> >- struct memtx_tree_data *check =
>> >+ struct memtx_tree_data<USE_HINT> *check =
>> >  memtx_tree_iterator_get_elem(&index->tree, &it->tree_iterator);
>> >  if (check == NULL || !memtx_tree_data_is_equal(check, &it->current)) {
>> >  it->tree_iterator = memtx_tree_upper_bound_elem(&index->tree,
>> >@@ -251,7 +351,7 @@ tree_iterator_next_equal_base(struct iterator *iterator, struct tuple **ret)
>> >  memtx_tree_iterator_next(&index->tree, &it->tree_iterator);
>> >  }
>> >  tuple_unref(it->current.tuple);
>> >- struct memtx_tree_data *res =
>> >+ struct memtx_tree_data<USE_HINT> *res =
>> >  memtx_tree_iterator_get_elem(&index->tree, &it->tree_iterator);
>> >  /* Use user key def to save a few loops. */
>> >  if (res == NULL ||
>> >@@ -271,14 +371,15 @@ tree_iterator_next_equal_base(struct iterator *iterator, struct tuple **ret)
>> >  return 0;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static int
>> > tree_iterator_prev_equal_base(struct iterator *iterator, struct tuple **ret)
>> > {
>> >- struct memtx_tree_index *index =
>> >- (struct memtx_tree_index *)iterator->index;
>> >- struct tree_iterator *it = tree_iterator(iterator);
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)iterator->index;
>> >+ struct tree_iterator<USE_HINT> *it = get_tree_iterator<USE_HINT>(iterator);
>> >  assert(it->current.tuple != NULL);
>> >- struct memtx_tree_data *check =
>> >+ struct memtx_tree_data<USE_HINT> *check =
>> >  memtx_tree_iterator_get_elem(&index->tree, &it->tree_iterator);
>> >  if (check == NULL || !memtx_tree_data_is_equal(check, &it->current)) {
>> >  it->tree_iterator = memtx_tree_lower_bound_elem(&index->tree,
>> >@@ -286,7 +387,7 @@ tree_iterator_prev_equal_base(struct iterator *iterator, struct tuple **ret)
>> >  }
>> >  memtx_tree_iterator_prev(&index->tree, &it->tree_iterator);
>> >  tuple_unref(it->current.tuple);
>> >- struct memtx_tree_data *res =
>> >+ struct memtx_tree_data<USE_HINT> *res =
>> >  memtx_tree_iterator_get_elem(&index->tree, &it->tree_iterator);
>> >  /* Use user key def to save a few loops. */
>> >  if (res == NULL ||
>> >@@ -307,28 +408,30 @@ tree_iterator_prev_equal_base(struct iterator *iterator, struct tuple **ret)
>> > }
>> > 
>> > #define WRAP_ITERATOR_METHOD(name) \
>> >+template <int USE_HINT> \
>> > static int \
>> > name(struct iterator *iterator, struct tuple **ret) \
>> > { \
>> >- struct memtx_tree *tree = \
>> >- &((struct memtx_tree_index *)iterator->index)->tree; \
>> >- struct tree_iterator *it = tree_iterator(iterator); \
>> >- struct memtx_tree_iterator *ti = &it->tree_iterator; \
>> >+ memtx_tree_t<USE_HINT> *tree = \
>> >+ &((struct memtx_tree_index<USE_HINT> *)iterator->index)->tree; \
>> >+ struct tree_iterator<USE_HINT> *it = \
>> >+ get_tree_iterator<USE_HINT>(iterator); \
>> >+ memtx_tree_iterator_t<USE_HINT> *ti = &it->tree_iterator; \
>> >  uint32_t iid = iterator->index->def->iid; \
>> >  bool is_multikey = iterator->index->def->key_def->is_multikey; \
>> >  struct txn *txn = in_txn(); \
>> >  struct space *space = space_by_id(iterator->space_id); \
>> >  bool is_rw = txn != NULL; \
>> >  do { \
>> >- int rc = name##_base(iterator, ret); \
>> >+ int rc = name##_base<USE_HINT>(iterator, ret); \
>> >  if (rc != 0 || *ret == NULL) \
>> >  return rc; \
>> >  uint32_t mk_index = 0; \
>> >  if (is_multikey) { \
>> >- struct memtx_tree_data *check = \
>> >+ struct memtx_tree_data<USE_HINT> *check = \
>> >  memtx_tree_iterator_get_elem(tree, ti); \
>> >  assert(check != NULL); \
>> >- mk_index = check->hint; \
>> >+ mk_index = (uint32_t)check->hint; \
>> >  } \
>> >  *ret = memtx_tx_tuple_clarify(txn, space, *ret, \
>> >  iid, mk_index, is_rw); \
>> >@@ -347,27 +450,28 @@ WRAP_ITERATOR_METHOD(tree_iterator_prev_equal);
>> > 
>> > #undef WRAP_ITERATOR_METHOD
>> > 
>> >+template <int USE_HINT>
>> > static void
>> >-tree_iterator_set_next_method(struct tree_iterator *it)
>> >+tree_iterator_set_next_method(struct tree_iterator<USE_HINT> *it)
>> > {
>> >  assert(it->current.tuple != NULL);
>> >  switch (it->type) {
>> >  case ITER_EQ:
>> >- it->base.next = tree_iterator_next_equal;
>> >+ it->base.next = tree_iterator_next_equal<USE_HINT>;
>> >  break;
>> >  case ITER_REQ:
>> >- it->base.next = tree_iterator_prev_equal;
>> >+ it->base.next = tree_iterator_prev_equal<USE_HINT>;
>> >  break;
>> >  case ITER_ALL:
>> >- it->base.next = tree_iterator_next;
>> >+ it->base.next = tree_iterator_next<USE_HINT>;
>> >  break;
>> >  case ITER_LT:
>> >  case ITER_LE:
>> >- it->base.next = tree_iterator_prev;
>> >+ it->base.next = tree_iterator_prev<USE_HINT>;
>> >  break;
>> >  case ITER_GE:
>> >  case ITER_GT:
>> >- it->base.next = tree_iterator_next;
>> >+ it->base.next = tree_iterator_next<USE_HINT>;
>> >  break;
>> >  default:
>> >  /* The type was checked in initIterator */
>> >@@ -375,15 +479,16 @@ tree_iterator_set_next_method(struct tree_iterator *it)
>> >  }
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static int
>> > tree_iterator_start(struct iterator *iterator, struct tuple **ret)
>> > {
>> >  *ret = NULL;
>> >- struct memtx_tree_index *index =
>> >- (struct memtx_tree_index *)iterator->index;
>> >- struct tree_iterator *it = tree_iterator(iterator);
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)iterator->index;
>> >+ struct tree_iterator<USE_HINT> *it = get_tree_iterator<USE_HINT>(iterator);
>> >  it->base.next = tree_iterator_dummie;
>> >- struct memtx_tree *tree = &index->tree;
>> >+ memtx_tree_t<USE_HINT> *tree = &index->tree;
>> >  enum iterator_type type = it->type;
>> >  bool exact = false;
>> >  assert(it->current.tuple == NULL);
>> >@@ -423,8 +528,8 @@ tree_iterator_start(struct iterator *iterator, struct tuple **ret)
>> >  }
>> >  }
>> > 
>> >- struct memtx_tree_data *res = memtx_tree_iterator_get_elem(tree,
>> >- &it->tree_iterator);
>> >+ struct memtx_tree_data<USE_HINT> *res =
>> >+ memtx_tree_iterator_get_elem(tree, &it->tree_iterator);
>> >  if (!res)
>> >  return 0;
>> >  *ret = res->tuple;
>> >@@ -454,14 +559,16 @@ tree_iterator_start(struct iterator *iterator, struct tuple **ret)
>> > 
>> > /* {{{ MemtxTree **********************************************************/
>> > 
>> >+template <int USE_HINT>
>> > static void
>> >-memtx_tree_index_free(struct memtx_tree_index *index)
>> >+memtx_tree_index_free(struct memtx_tree_index<USE_HINT> *index)
>> > {
>> >  memtx_tree_destroy(&index->tree);
>> >  free(index->build_array);
>> >  free(index);
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static void
>> > memtx_tree_index_gc_run(struct memtx_gc_task *task, bool *done)
>> > {
>> >@@ -475,14 +582,14 @@ memtx_tree_index_gc_run(struct memtx_gc_task *task, bool *done)
>> >  enum { YIELD_LOOPS = 10 };
>> > #endif
>> > 
>> >- struct memtx_tree_index *index = container_of(task,
>> >- struct memtx_tree_index, gc_task);
>> >- struct memtx_tree *tree = &index->tree;
>> >- struct memtx_tree_iterator *itr = &index->gc_iterator;
>> >+ struct memtx_tree_index<USE_HINT> *index = container_of(task,
>> >+ struct memtx_tree_index<USE_HINT>, gc_task);
>> >+ memtx_tree_t<USE_HINT> *tree = &index->tree;
>> >+ memtx_tree_iterator_t<USE_HINT> *itr = &index->gc_iterator;
>> > 
>> >  unsigned int loops = 0;
>> >  while (!memtx_tree_iterator_is_invalid(itr)) {
>> >- struct memtx_tree_data *res =
>> >+ struct memtx_tree_data<USE_HINT> *res =
>> >  memtx_tree_iterator_get_elem(tree, itr);
>> >  memtx_tree_iterator_next(tree, itr);
>> >  tuple_unref(res->tuple);
>> >@@ -494,23 +601,32 @@ memtx_tree_index_gc_run(struct memtx_gc_task *task, bool *done)
>> >  *done = true;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static void
>> > memtx_tree_index_gc_free(struct memtx_gc_task *task)
>> > {
>> >- struct memtx_tree_index *index = container_of(task,
>> >- struct memtx_tree_index, gc_task);
>> >+ struct memtx_tree_index<USE_HINT> *index = container_of(task,
>> >+ struct memtx_tree_index<USE_HINT>, gc_task);
>> >  memtx_tree_index_free(index);
>> > }
>> > 
>> >-static const struct memtx_gc_task_vtab memtx_tree_index_gc_vtab = {
>> >- .run = memtx_tree_index_gc_run,
>> >- .free = memtx_tree_index_gc_free,
>> >+template <int USE_HINT>
>> >+static struct memtx_gc_task_vtab * get_memtx_tree_index_gc_vtab()
>> >+{
>> >+ static memtx_gc_task_vtab tab =
>> >+ {
>> >+ .run = memtx_tree_index_gc_run<USE_HINT>,
>> >+ .free = memtx_tree_index_gc_free<USE_HINT>,
>> >+ };
>> >+ return &tab;
>> > };
>> > 
>> >+template <int USE_HINT>
>> > static void
>> > memtx_tree_index_destroy(struct index *base)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)base;
>> >  struct memtx_engine *memtx = (struct memtx_engine *)base->engine;
>> >  if (base->def->iid == 0) {
>> >  /*
>> >@@ -518,7 +634,7 @@ memtx_tree_index_destroy(struct index *base)
>> >  * in the index, which may take a while. Schedule a
>> >  * background task in order not to block tx thread.
>> >  */
>> >- index->gc_task.vtab = &memtx_tree_index_gc_vtab;
>> >+ index->gc_task.vtab = get_memtx_tree_index_gc_vtab<USE_HINT>();
>> >  index->gc_iterator = memtx_tree_iterator_first(&index->tree);
>> >  memtx_engine_schedule_gc(memtx, &index->gc_task);
>> >  } else {
>> >@@ -530,10 +646,12 @@ memtx_tree_index_destroy(struct index *base)
>> >  }
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static void
>> > memtx_tree_index_update_def(struct index *base)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)base;
>> >  struct index_def *def = base->def;
>> >  /*
>> >  * We use extended key def for non-unique and nullable
>> >@@ -553,51 +671,62 @@ memtx_tree_index_depends_on_pk(struct index *base)
>> >  return !def->opts.is_unique || def->key_def->is_nullable;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static ssize_t
>> > memtx_tree_index_size(struct index *base)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)base;
>> >  return memtx_tree_size(&index->tree);
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static ssize_t
>> > memtx_tree_index_bsize(struct index *base)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)base;
>> >  return memtx_tree_mem_used(&index->tree);
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static int
>> > memtx_tree_index_random(struct index *base, uint32_t rnd, struct tuple **result)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >- struct memtx_tree_data *res = memtx_tree_random(&index->tree, rnd);
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)base;
>> >+ struct memtx_tree_data<USE_HINT> *res = memtx_tree_random(&index->tree, rnd);
>> >  *result = res != NULL ? res->tuple : NULL;
>> >  return 0;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static ssize_t
>> > memtx_tree_index_count(struct index *base, enum iterator_type type,
>> >  const char *key, uint32_t part_count)
>> > {
>> >  if (type == ITER_ALL)
>> >- return memtx_tree_index_size(base); /* optimization */
>> >+ return memtx_tree_index_size<USE_HINT>(base); /* optimization */
>> >  return generic_index_count(base, type, key, part_count);
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static int
>> > memtx_tree_index_get(struct index *base, const char *key,
>> >  uint32_t part_count, struct tuple **result)
>> > {
>> >  assert(base->def->opts.is_unique &&
>> >  part_count == base->def->key_def->part_count);
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)base;
>> >  struct key_def *cmp_def = memtx_tree_cmp_def(&index->tree);
>> >- struct memtx_tree_key_data key_data;
>> >+ struct memtx_tree_key_data<USE_HINT> key_data;
>> >  key_data.key = key;
>> >  key_data.part_count = part_count;
>> >- key_data.hint = key_hint(key, part_count, cmp_def);
>> >- struct memtx_tree_data *res = memtx_tree_find(&index->tree, &key_data);
>> >+ if (USE_HINT)
>> >+ key_data.set_hint(key_hint(key, part_count, cmp_def));
>> >+ struct memtx_tree_data<USE_HINT> *res =
>> >+ memtx_tree_find(&index->tree, &key_data);
>> >  if (res == NULL) {
>> >  *result = NULL;
>> >  return 0;
>> >@@ -611,18 +740,21 @@ memtx_tree_index_get(struct index *base, const char *key,
>> >  return 0;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static int
>> > memtx_tree_index_replace(struct index *base, struct tuple *old_tuple,
>> >  struct tuple *new_tuple, enum dup_replace_mode mode,
>> >  struct tuple **result)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)base;
>> >  struct key_def *cmp_def = memtx_tree_cmp_def(&index->tree);
>> >  if (new_tuple) {
>> >- struct memtx_tree_data new_data;
>> >+ struct memtx_tree_data<USE_HINT> new_data;
>> >  new_data.tuple = new_tuple;
>> >- new_data.hint = tuple_hint(new_tuple, cmp_def);
>> >- struct memtx_tree_data dup_data;
>> >+ if (USE_HINT)
>> >+ new_data.set_hint(tuple_hint(new_tuple, cmp_def));
>> >+ struct memtx_tree_data<USE_HINT> dup_data;
>> >  dup_data.tuple = NULL;
>> > 
>> >  /* Try to optimistically replace the new_tuple. */
>> >@@ -652,9 +784,10 @@ memtx_tree_index_replace(struct index *base, struct tuple *old_tuple,
>> >  }
>> >  }
>> >  if (old_tuple) {
>> >- struct memtx_tree_data old_data;
>> >+ struct memtx_tree_data<USE_HINT> old_data;
>> >  old_data.tuple = old_tuple;
>> >- old_data.hint = tuple_hint(old_tuple, cmp_def);
>> >+ if (USE_HINT)
>> >+ old_data.set_hint(tuple_hint(old_tuple, cmp_def));
>> >  memtx_tree_delete(&index->tree, old_data);
>> >  }
>> >  *result = old_tuple;
>> >@@ -667,13 +800,13 @@ memtx_tree_index_replace(struct index *base, struct tuple *old_tuple,
>> >  * by all it's multikey indexes.
>> >  */
>> > static int
>> >-memtx_tree_index_replace_multikey_one(struct memtx_tree_index *index,
>> >+memtx_tree_index_replace_multikey_one(struct memtx_tree_index<1> *index,
>> >  struct tuple *old_tuple, struct tuple *new_tuple,
>> >  enum dup_replace_mode mode, hint_t hint,
>> >- struct memtx_tree_data *replaced_data,
>> >+ struct memtx_tree_data<1> *replaced_data,
>> >  bool *is_multikey_conflict)
>> > {
>> >- struct memtx_tree_data new_data, dup_data;
>> >+ struct memtx_tree_data<1> new_data, dup_data;
>> >  new_data.tuple = new_tuple;
>> >  new_data.hint = hint;
>> >  dup_data.tuple = NULL;
>> >@@ -720,11 +853,11 @@ memtx_tree_index_replace_multikey_one(struct memtx_tree_index *index,
>> >  * delete operation is fault-tolerant.
>> >  */
>> > static void
>> >-memtx_tree_index_replace_multikey_rollback(struct memtx_tree_index *index,
>> >+memtx_tree_index_replace_multikey_rollback(struct memtx_tree_index<1> *index,
>> >  struct tuple *new_tuple, struct tuple *replaced_tuple,
>> >  int err_multikey_idx)
>> > {
>> >- struct memtx_tree_data data;
>> >+ struct memtx_tree_data<1> data;
>> >  if (replaced_tuple != NULL) {
>> >  /* Restore replaced tuple index occurrences. */
>> >  struct key_def *cmp_def = memtx_tree_cmp_def(&index->tree);
>> >@@ -798,7 +931,7 @@ memtx_tree_index_replace_multikey(struct index *base, struct tuple *old_tuple,
>> >  struct tuple *new_tuple, enum dup_replace_mode mode,
>> >  struct tuple **result)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<1> *index = (struct memtx_tree_index<1> *)base;
>> >  struct key_def *cmp_def = memtx_tree_cmp_def(&index->tree);
>> >  *result = NULL;
>> >  if (new_tuple != NULL) {
>> >@@ -808,7 +941,7 @@ memtx_tree_index_replace_multikey(struct index *base, struct tuple *old_tuple,
>> >  for (; (uint32_t) multikey_idx < multikey_count;
>> >  multikey_idx++) {
>> >  bool is_multikey_conflict;
>> >- struct memtx_tree_data replaced_data;
>> >+ struct memtx_tree_data<1> replaced_data;
>> >  err = memtx_tree_index_replace_multikey_one(index,
>> >  old_tuple, new_tuple, mode,
>> >  multikey_idx, &replaced_data,
>> >@@ -833,7 +966,7 @@ memtx_tree_index_replace_multikey(struct index *base, struct tuple *old_tuple,
>> >  }
>> >  }
>> >  if (old_tuple != NULL) {
>> >- struct memtx_tree_data data;
>> >+ struct memtx_tree_data<1> data;
>> >  data.tuple = old_tuple;
>> >  uint32_t multikey_count =
>> >  tuple_multikey_count(old_tuple, cmp_def);
>> >@@ -865,7 +998,7 @@ struct func_key_undo {
>> >  /** A link to organize entries in list. */
>> >  struct rlist link;
>> >  /** An inserted record copy. */
>> >- struct memtx_tree_data key;
>> >+ struct memtx_tree_data<1> key;
>> > };
>> > 
>> > /** Allocate a new func_key_undo on given region. */
>> >@@ -888,7 +1021,7 @@ func_key_undo_new(struct region *region)
>> >  * return a given index object in it's original state.
>> >  */
>> > static void
>> >-memtx_tree_func_index_replace_rollback(struct memtx_tree_index *index,
>> >+memtx_tree_func_index_replace_rollback(struct memtx_tree_index<1> *index,
>> >  struct rlist *old_keys,
>> >  struct rlist *new_keys)
>> > {
>> >@@ -919,7 +1052,7 @@ memtx_tree_func_index_replace(struct index *base, struct tuple *old_tuple,
>> >  struct tuple *new_tuple, enum dup_replace_mode mode,
>> >  struct tuple **result)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<1> *index = (struct memtx_tree_index<1> *)base;
>> >  struct index_def *index_def = index->base.def;
>> >  assert(index_def->key_def->for_func_index);
>> > 
>> >@@ -952,7 +1085,7 @@ memtx_tree_func_index_replace(struct index *base, struct tuple *old_tuple,
>> >  undo->key.hint = (hint_t)key;
>> >  rlist_add(&new_keys, &undo->link);
>> >  bool is_multikey_conflict;
>> >- struct memtx_tree_data old_data;
>> >+ struct memtx_tree_data<1> old_data;
>> >  old_data.tuple = NULL;
>> >  err = memtx_tree_index_replace_multikey_one(index,
>> >  old_tuple, new_tuple,
>> >@@ -1015,7 +1148,7 @@ memtx_tree_func_index_replace(struct index *base, struct tuple *old_tuple,
>> >  if (key_list_iterator_create(&it, old_tuple, index_def, false,
>> >  func_index_key_dummy_alloc) != 0)
>> >  goto end;
>> >- struct memtx_tree_data data, deleted_data;
>> >+ struct memtx_tree_data<1> data, deleted_data;
>> >  data.tuple = old_tuple;
>> >  const char *key;
>> >  while (key_list_iterator_next(&it, &key) == 0 && key != NULL) {
>> >@@ -1040,11 +1173,13 @@ end:
>> >  return rc;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static struct iterator *
>> > memtx_tree_index_create_iterator(struct index *base, enum iterator_type type,
>> >  const char *key, uint32_t part_count)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)base;
>> >  struct memtx_engine *memtx = (struct memtx_engine *)base->engine;
>> >  struct key_def *cmp_def = memtx_tree_cmp_def(&index->tree);
>> > 
>> >@@ -1064,42 +1199,47 @@ memtx_tree_index_create_iterator(struct index *base, enum iterator_type type,
>> >  key = NULL;
>> >  }
>> > 
>> >- struct tree_iterator *it = (struct tree_iterator *)
>> >+ struct tree_iterator<USE_HINT> *it = (struct tree_iterator<USE_HINT> *)
>> >  mempool_alloc(&memtx->iterator_pool);
>> >  if (it == NULL) {
>> >- diag_set(OutOfMemory, sizeof(struct tree_iterator),
>> >+ diag_set(OutOfMemory, sizeof(struct tree_iterator<USE_HINT>),
>> >  "memtx_tree_index", "iterator");
>> >  return NULL;
>> >  }
>> >  iterator_create(&it->base, base);
>> >  it->pool = &memtx->iterator_pool;
>> >- it->base.next = tree_iterator_start;
>> >- it->base.free = tree_iterator_free;
>> >+ it->base.next = tree_iterator_start<USE_HINT>;
>> >+ it->base.free = tree_iterator_free<USE_HINT>;
>> >  it->type = type;
>> >  it->key_data.key = key;
>> >  it->key_data.part_count = part_count;
>> >- it->key_data.hint = key_hint(key, part_count, cmp_def);
>> >- it->tree_iterator = memtx_tree_invalid_iterator();
>> >+ if (USE_HINT)
>> >+ it->key_data.set_hint(key_hint(key, part_count, cmp_def));
>> >+ invalidate_tree_iterator(&it->tree_iterator);
>> >  it->current.tuple = NULL;
>> >  return (struct iterator *)it;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static void
>> > memtx_tree_index_begin_build(struct index *base)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)base;
>> >  assert(memtx_tree_size(&index->tree) == 0);
>> >  (void)index;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static int
>> > memtx_tree_index_reserve(struct index *base, uint32_t size_hint)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)base;
>> >  if (size_hint < index->build_array_alloc_size)
>> >  return 0;
>> >- struct memtx_tree_data *tmp =
>> >- (struct memtx_tree_data *)
>> >+ struct memtx_tree_data<USE_HINT> *tmp =
>> >+ (struct memtx_tree_data<USE_HINT> *)
>> >  realloc(index->build_array, size_hint * sizeof(*tmp));
>> >  if (tmp == NULL) {
>> >  diag_set(OutOfMemory, size_hint * sizeof(*tmp),
>> >@@ -1111,14 +1251,15 @@ memtx_tree_index_reserve(struct index *base, uint32_t size_hint)
>> >  return 0;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > /** Initialize the next element of the index build_array. */
>> > static int
>> >-memtx_tree_index_build_array_append(struct memtx_tree_index *index,
>> >+memtx_tree_index_build_array_append(struct memtx_tree_index<USE_HINT> *index,
>> >  struct tuple *tuple, hint_t hint)
>> > {
>> >  if (index->build_array == NULL) {
>> >  index->build_array =
>> >- (struct memtx_tree_data *)malloc(MEMTX_EXTENT_SIZE);
>> >+ (struct memtx_tree_data<USE_HINT> *)malloc(MEMTX_EXTENT_SIZE);
>> >  if (index->build_array == NULL) {
>> >  diag_set(OutOfMemory, MEMTX_EXTENT_SIZE,
>> >  "memtx_tree_index", "build_next");
>> >@@ -1131,8 +1272,8 @@ memtx_tree_index_build_array_append(struct memtx_tree_index *index,
>> >  if (index->build_array_size == index->build_array_alloc_size) {
>> >  index->build_array_alloc_size = index->build_array_alloc_size +
>> >  DIV_ROUND_UP(index->build_array_alloc_size, 2);
>> >- struct memtx_tree_data *tmp =
>> >- (struct memtx_tree_data *)realloc(index->build_array,
>> >+ struct memtx_tree_data<USE_HINT> *tmp =
>> >+ (struct memtx_tree_data<USE_HINT> *)realloc(index->build_array,
>> >  index->build_array_alloc_size * sizeof(*tmp));
>> >  if (tmp == NULL) {
>> >  diag_set(OutOfMemory, index->build_array_alloc_size *
>> >@@ -1141,17 +1282,20 @@ memtx_tree_index_build_array_append(struct memtx_tree_index *index,
>> >  }
>> >  index->build_array = tmp;
>> >  }
>> >- struct memtx_tree_data *elem =
>> >+ struct memtx_tree_data<USE_HINT> *elem =
>> >  &index->build_array[index->build_array_size++];
>> >  elem->tuple = tuple;
>> >- elem->hint = hint;
>> >+ if (USE_HINT)
>> >+ elem->set_hint(hint);
>> >  return 0;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static int
>> > memtx_tree_index_build_next(struct index *base, struct tuple *tuple)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)base;
>> >  struct key_def *cmp_def = memtx_tree_cmp_def(&index->tree);
>> >  return memtx_tree_index_build_array_append(index, tuple,
>> >  tuple_hint(tuple, cmp_def));
>> >@@ -1160,7 +1304,7 @@ memtx_tree_index_build_next(struct index *base, struct tuple *tuple)
>> > static int
>> > memtx_tree_index_build_next_multikey(struct index *base, struct tuple *tuple)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<1> *index = (struct memtx_tree_index<1> *)base;
>> >  struct key_def *cmp_def = memtx_tree_cmp_def(&index->tree);
>> >  uint32_t multikey_count = tuple_multikey_count(tuple, cmp_def);
>> >  for (uint32_t multikey_idx = 0; multikey_idx < multikey_count;
>> >@@ -1175,7 +1319,7 @@ memtx_tree_index_build_next_multikey(struct index *base, struct tuple *tuple)
>> > static int
>> > memtx_tree_func_index_build_next(struct index *base, struct tuple *tuple)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<1> *index = (struct memtx_tree_index<1> *)base;
>> >  struct index_def *index_def = index->base.def;
>> >  assert(index_def->key_def->for_func_index);
>> > 
>> >@@ -1211,8 +1355,9 @@ error:
>> >  * of equal tuples (in terms of index's cmp_def and have same
>> >  * tuple pointer). The build_array is expected to be sorted.
>> >  */
>> >+template <int USE_HINT>
>> > static void
>> >-memtx_tree_index_build_array_deduplicate(struct memtx_tree_index *index,
>> >+memtx_tree_index_build_array_deduplicate(struct memtx_tree_index<USE_HINT> *index,
>> >  void (*destroy)(struct tuple *tuple, const char *hint))
>> > {
>> >  if (index->build_array_size == 0)
>> >@@ -1246,13 +1391,16 @@ memtx_tree_index_build_array_deduplicate(struct memtx_tree_index *index,
>> >  index->build_array_size = w_idx + 1;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static void
>> > memtx_tree_index_end_build(struct index *base)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)base;
>> >  struct key_def *cmp_def = memtx_tree_cmp_def(&index->tree);
>> >  qsort_arg(index->build_array, index->build_array_size,
>> >- sizeof(index->build_array[0]), memtx_tree_qcompare, cmp_def);
>> >+ sizeof(index->build_array[0]),
>> >+ memtx_tree_qcompare<USE_HINT>, cmp_def);
>> >  if (cmp_def->is_multikey) {
>> >  /*
>> >  * Multikey index may have equal(in terms of
>> >@@ -1261,9 +1409,9 @@ memtx_tree_index_end_build(struct index *base)
>> >  * the following memtx_tree_build assumes that
>> >  * all keys are unique.
>> >  */
>> >- memtx_tree_index_build_array_deduplicate(index, NULL);
>> >+ memtx_tree_index_build_array_deduplicate<USE_HINT>(index, NULL);
>> >  } else if (cmp_def->for_func_index) {
>> >- memtx_tree_index_build_array_deduplicate(index,
>> >+ memtx_tree_index_build_array_deduplicate<USE_HINT>(index,
>> >  tuple_chunk_delete);
>> >  }
>> >  memtx_tree_build(&index->tree, index->build_array,
>> >@@ -1275,19 +1423,21 @@ memtx_tree_index_end_build(struct index *base)
>> >  index->build_array_alloc_size = 0;
>> > }
>> > 
>> >+template <int USE_HINT>
>> > struct tree_snapshot_iterator {
>> >  struct snapshot_iterator base;
>> >- struct memtx_tree_index *index;
>> >- struct memtx_tree_iterator tree_iterator;
>> >+ struct memtx_tree_index<USE_HINT> *index;
>> >+ memtx_tree_iterator_t<USE_HINT> tree_iterator;
>> >  struct memtx_tx_snapshot_cleaner cleaner;
>> > };
>> > 
>> >+template <int USE_HINT>
>> > static void
>> > tree_snapshot_iterator_free(struct snapshot_iterator *iterator)
>> > {
>> >- assert(iterator->free == tree_snapshot_iterator_free);
>> >- struct tree_snapshot_iterator *it =
>> >- (struct tree_snapshot_iterator *)iterator;
>> >+ assert(iterator->free == &tree_snapshot_iterator_free<USE_HINT>);
>> >+ struct tree_snapshot_iterator<USE_HINT> *it =
>> >+ (struct tree_snapshot_iterator<USE_HINT> *)iterator;
>> >  memtx_leave_delayed_free_mode((struct memtx_engine *)
>> >  it->index->base.engine);
>> >  memtx_tree_iterator_destroy(&it->index->tree, &it->tree_iterator);
>> >@@ -1296,17 +1446,18 @@ tree_snapshot_iterator_free(struct snapshot_iterator *iterator)
>> >  free(iterator);
>> > }
>> > 
>> >+template <int USE_HINT>
>> > static int
>> > tree_snapshot_iterator_next(struct snapshot_iterator *iterator,
>> >  const char **data, uint32_t *size)
>> > {
>> >- assert(iterator->free == tree_snapshot_iterator_free);
>> >- struct tree_snapshot_iterator *it =
>> >- (struct tree_snapshot_iterator *)iterator;
>> >- struct memtx_tree *tree = &it->index->tree;
>> >+ assert(iterator->free == &tree_snapshot_iterator_free<USE_HINT>);
>> >+ struct tree_snapshot_iterator<USE_HINT> *it =
>> >+ (struct tree_snapshot_iterator<USE_HINT> *)iterator;
>> >+ memtx_tree_t<USE_HINT> *tree = &it->index->tree;
>> > 
>> >  while (true) {
>> >- struct memtx_tree_data *res =
>> >+ struct memtx_tree_data<USE_HINT> *res =
>> >  memtx_tree_iterator_get_elem(tree, &it->tree_iterator);
>> > 
>> >  if (res == NULL) {
>> >@@ -1333,14 +1484,18 @@ tree_snapshot_iterator_next(struct snapshot_iterator *iterator,
>> >  * index modifications will not affect the iteration results.
>> >  * Must be destroyed by iterator->free after usage.
>> >  */
>> >+template <int USE_HINT>
>> > static struct snapshot_iterator *
>> > memtx_tree_index_create_snapshot_iterator(struct index *base)
>> > {
>> >- struct memtx_tree_index *index = (struct memtx_tree_index *)base;
>> >- struct tree_snapshot_iterator *it =
>> >- (struct tree_snapshot_iterator *) calloc(1, sizeof(*it));
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)base;
>> >+ struct tree_snapshot_iterator<USE_HINT> *it =
>> >+ (struct tree_snapshot_iterator<USE_HINT> *)
>> >+ calloc(1, sizeof(*it));
>> >  if (it == NULL) {
>> >- diag_set(OutOfMemory, sizeof(struct tree_snapshot_iterator),
>> >+ diag_set(OutOfMemory,
>> >+ sizeof(struct tree_snapshot_iterator<USE_HINT>),
>> >  "memtx_tree_index", "create_snapshot_iterator");
>> >  return NULL;
>> >  }
>> >@@ -1352,8 +1507,8 @@ memtx_tree_index_create_snapshot_iterator(struct index *base)
>> >  return NULL;
>> >  }
>> > 
>> >- it->base.free = tree_snapshot_iterator_free;
>> >- it->base.next = tree_snapshot_iterator_next;
>> >+ it->base.free = tree_snapshot_iterator_free<USE_HINT>;
>> >+ it->base.next = tree_snapshot_iterator_next<USE_HINT>;
>> >  it->index = index;
>> >  index_ref(base);
>> >  it->tree_iterator = memtx_tree_iterator_first(&index->tree);
>> >@@ -1362,94 +1517,124 @@ memtx_tree_index_create_snapshot_iterator(struct index *base)
>> >  return (struct snapshot_iterator *) it;
>> > }
>> > 
>> >-static const struct index_vtab memtx_tree_index_vtab = {
>> >- /* .destroy = */ memtx_tree_index_destroy,
>> >+static const struct index_vtab memtx_tree_no_hint_index_vtab = {
>> >+ /* .destroy = */ memtx_tree_index_destroy<0>,
>> >  /* .commit_create = */ generic_index_commit_create,
>> >  /* .abort_create = */ generic_index_abort_create,
>> >  /* .commit_modify = */ generic_index_commit_modify,
>> >  /* .commit_drop = */ generic_index_commit_drop,
>> >- /* .update_def = */ memtx_tree_index_update_def,
>> >+ /* .update_def = */ memtx_tree_index_update_def<0>,
>> >  /* .depends_on_pk = */ memtx_tree_index_depends_on_pk,
>> >  /* .def_change_requires_rebuild = */
>> >  memtx_index_def_change_requires_rebuild,
>> >- /* .size = */ memtx_tree_index_size,
>> >- /* .bsize = */ memtx_tree_index_bsize,
>> >+ /* .size = */ memtx_tree_index_size<0>,
>> >+ /* .bsize = */ memtx_tree_index_bsize<0>,
>> >  /* .min = */ generic_index_min,
>> >  /* .max = */ generic_index_max,
>> >- /* .random = */ memtx_tree_index_random,
>> >- /* .count = */ memtx_tree_index_count,
>> >- /* .get = */ memtx_tree_index_get,
>> >- /* .replace = */ memtx_tree_index_replace,
>> >- /* .create_iterator = */ memtx_tree_index_create_iterator,
>> >+ /* .random = */ memtx_tree_index_random<0>,
>> >+ /* .count = */ memtx_tree_index_count<0>,
>> >+ /* .get = */ memtx_tree_index_get<0>,
>> >+ /* .replace = */ memtx_tree_index_replace<0>,
>> >+ /* .create_iterator = */ memtx_tree_index_create_iterator<0>,
>> >  /* .create_snapshot_iterator = */
>> >- memtx_tree_index_create_snapshot_iterator,
>> >+ memtx_tree_index_create_snapshot_iterator<0>,
>> >  /* .stat = */ generic_index_stat,
>> >  /* .compact = */ generic_index_compact,
>> >  /* .reset_stat = */ generic_index_reset_stat,
>> >- /* .begin_build = */ memtx_tree_index_begin_build,
>> >- /* .reserve = */ memtx_tree_index_reserve,
>> >- /* .build_next = */ memtx_tree_index_build_next,
>> >- /* .end_build = */ memtx_tree_index_end_build,
>> >+ /* .begin_build = */ memtx_tree_index_begin_build<0>,
>> >+ /* .reserve = */ memtx_tree_index_reserve<0>,
>> >+ /* .build_next = */ memtx_tree_index_build_next<0>,
>> >+ /* .end_build = */ memtx_tree_index_end_build<0>,
>> >+};
>> >+
>> >+static const struct index_vtab memtx_tree_use_hint_index_vtab = {
>> >+ /* .destroy = */ memtx_tree_index_destroy<1>,
>> >+ /* .commit_create = */ generic_index_commit_create,
>> >+ /* .abort_create = */ generic_index_abort_create,
>> >+ /* .commit_modify = */ generic_index_commit_modify,
>> >+ /* .commit_drop = */ generic_index_commit_drop,
>> >+ /* .update_def = */ memtx_tree_index_update_def<1>,
>> >+ /* .depends_on_pk = */ memtx_tree_index_depends_on_pk,
>> >+ /* .def_change_requires_rebuild = */
>> >+ memtx_index_def_change_requires_rebuild,
>> >+ /* .size = */ memtx_tree_index_size<1>,
>> >+ /* .bsize = */ memtx_tree_index_bsize<1>,
>> >+ /* .min = */ generic_index_min,
>> >+ /* .max = */ generic_index_max,
>> >+ /* .random = */ memtx_tree_index_random<1>,
>> >+ /* .count = */ memtx_tree_index_count<1>,
>> >+ /* .get = */ memtx_tree_index_get<1>,
>> >+ /* .replace = */ memtx_tree_index_replace<1>,
>> >+ /* .create_iterator = */ memtx_tree_index_create_iterator<1>,
>> >+ /* .create_snapshot_iterator = */
>> >+ memtx_tree_index_create_snapshot_iterator<1>,
>> >+ /* .stat = */ generic_index_stat,
>> >+ /* .compact = */ generic_index_compact,
>> >+ /* .reset_stat = */ generic_index_reset_stat,
>> >+ /* .begin_build = */ memtx_tree_index_begin_build<1>,
>> >+ /* .reserve = */ memtx_tree_index_reserve<1>,
>> >+ /* .build_next = */ memtx_tree_index_build_next<1>,
>> >+ /* .end_build = */ memtx_tree_index_end_build<1>,
>> > };
>> > 
>> > static const struct index_vtab memtx_tree_index_multikey_vtab = {
>> >- /* .destroy = */ memtx_tree_index_destroy,
>> >+ /* .destroy = */ memtx_tree_index_destroy<1>,
>> >  /* .commit_create = */ generic_index_commit_create,
>> >  /* .abort_create = */ generic_index_abort_create,
>> >  /* .commit_modify = */ generic_index_commit_modify,
>> >  /* .commit_drop = */ generic_index_commit_drop,
>> >- /* .update_def = */ memtx_tree_index_update_def,
>> >+ /* .update_def = */ memtx_tree_index_update_def<1>,
>> >  /* .depends_on_pk = */ memtx_tree_index_depends_on_pk,
>> >  /* .def_change_requires_rebuild = */
>> >  memtx_index_def_change_requires_rebuild,
>> >- /* .size = */ memtx_tree_index_size,
>> >- /* .bsize = */ memtx_tree_index_bsize,
>> >+ /* .size = */ memtx_tree_index_size<1>,
>> >+ /* .bsize = */ memtx_tree_index_bsize<1>,
>> >  /* .min = */ generic_index_min,
>> >  /* .max = */ generic_index_max,
>> >- /* .random = */ memtx_tree_index_random,
>> >- /* .count = */ memtx_tree_index_count,
>> >- /* .get = */ memtx_tree_index_get,
>> >+ /* .random = */ memtx_tree_index_random<1>,
>> >+ /* .count = */ memtx_tree_index_count<1>,
>> >+ /* .get = */ memtx_tree_index_get<1>,
>> >  /* .replace = */ memtx_tree_index_replace_multikey,
>> >- /* .create_iterator = */ memtx_tree_index_create_iterator,
>> >+ /* .create_iterator = */ memtx_tree_index_create_iterator<1>,
>> >  /* .create_snapshot_iterator = */
>> >- memtx_tree_index_create_snapshot_iterator,
>> >+ memtx_tree_index_create_snapshot_iterator<1>,
>> >  /* .stat = */ generic_index_stat,
>> >  /* .compact = */ generic_index_compact,
>> >  /* .reset_stat = */ generic_index_reset_stat,
>> >- /* .begin_build = */ memtx_tree_index_begin_build,
>> >- /* .reserve = */ memtx_tree_index_reserve,
>> >+ /* .begin_build = */ memtx_tree_index_begin_build<1>,
>> >+ /* .reserve = */ memtx_tree_index_reserve<1>,
>> >  /* .build_next = */ memtx_tree_index_build_next_multikey,
>> >- /* .end_build = */ memtx_tree_index_end_build,
>> >+ /* .end_build = */ memtx_tree_index_end_build<1>,
>> > };
>> > 
>> > static const struct index_vtab memtx_tree_func_index_vtab = {
>> >- /* .destroy = */ memtx_tree_index_destroy,
>> >+ /* .destroy = */ memtx_tree_index_destroy<1>,
>> >  /* .commit_create = */ generic_index_commit_create,
>> >  /* .abort_create = */ generic_index_abort_create,
>> >  /* .commit_modify = */ generic_index_commit_modify,
>> >  /* .commit_drop = */ generic_index_commit_drop,
>> >- /* .update_def = */ memtx_tree_index_update_def,
>> >+ /* .update_def = */ memtx_tree_index_update_def<1>,
>> >  /* .depends_on_pk = */ memtx_tree_index_depends_on_pk,
>> >  /* .def_change_requires_rebuild = */
>> >  memtx_index_def_change_requires_rebuild,
>> >- /* .size = */ memtx_tree_index_size,
>> >- /* .bsize = */ memtx_tree_index_bsize,
>> >+ /* .size = */ memtx_tree_index_size<1>,
>> >+ /* .bsize = */ memtx_tree_index_bsize<1>,
>> >  /* .min = */ generic_index_min,
>> >  /* .max = */ generic_index_max,
>> >- /* .random = */ memtx_tree_index_random,
>> >- /* .count = */ memtx_tree_index_count,
>> >- /* .get = */ memtx_tree_index_get,
>> >+ /* .random = */ memtx_tree_index_random<1>,
>> >+ /* .count = */ memtx_tree_index_count<1>,
>> >+ /* .get = */ memtx_tree_index_get<1>,
>> >  /* .replace = */ memtx_tree_func_index_replace,
>> >- /* .create_iterator = */ memtx_tree_index_create_iterator,
>> >+ /* .create_iterator = */ memtx_tree_index_create_iterator<1>,
>> >  /* .create_snapshot_iterator = */
>> >- memtx_tree_index_create_snapshot_iterator,
>> >+ memtx_tree_index_create_snapshot_iterator<1>,
>> >  /* .stat = */ generic_index_stat,
>> >  /* .compact = */ generic_index_compact,
>> >  /* .reset_stat = */ generic_index_reset_stat,
>> >- /* .begin_build = */ memtx_tree_index_begin_build,
>> >- /* .reserve = */ memtx_tree_index_reserve,
>> >+ /* .begin_build = */ memtx_tree_index_begin_build<1>,
>> >+ /* .reserve = */ memtx_tree_index_reserve<1>,
>> >  /* .build_next = */ memtx_tree_func_index_build_next,
>> >- /* .end_build = */ memtx_tree_index_end_build,
>> >+ /* .end_build = */ memtx_tree_index_end_build<1>,
>> > };
>> > 
>> > /**
>> >@@ -1459,7 +1644,7 @@ static const struct index_vtab memtx_tree_func_index_vtab = {
>> >  * key defintion is not completely initialized at that moment).
>> >  */
>> > static const struct index_vtab memtx_tree_disabled_index_vtab = {
>> >- /* .destroy = */ memtx_tree_index_destroy,
>> >+ /* .destroy = */ memtx_tree_index_destroy<1>,
>> >  /* .commit_create = */ generic_index_commit_create,
>> >  /* .abort_create = */ generic_index_abort_create,
>> >  /* .commit_modify = */ generic_index_commit_modify,
>> >@@ -1488,27 +1673,19 @@ static const struct index_vtab memtx_tree_disabled_index_vtab = {
>> >  /* .end_build = */ generic_index_end_build,
>> > };
>> > 
>> >-struct index *
>> >-memtx_tree_index_new(struct memtx_engine *memtx, struct index_def *def)
>> >+template <int USE_HINT>
>> >+static struct index *
>> >+memtx_tree_index_new_tpl(struct memtx_engine *memtx, struct index_def *def,
>> >+ const struct index_vtab *vtab)
>> > {
>> >- struct memtx_tree_index *index =
>> >- (struct memtx_tree_index *)calloc(1, sizeof(*index));
>> >+ struct memtx_tree_index<USE_HINT> *index =
>> >+ (struct memtx_tree_index<USE_HINT> *)
>> >+ calloc(1, sizeof(*index));
>> >  if (index == NULL) {
>> >  diag_set(OutOfMemory, sizeof(*index),
>> >  "malloc", "struct memtx_tree_index");
>> >  return NULL;
>> >  }
>> >- const struct index_vtab *vtab;
>> >- if (def->key_def->for_func_index) {
>> >- if (def->key_def->func_index_func == NULL)
>> >- vtab = &memtx_tree_disabled_index_vtab;
>> >- else
>> >- vtab = &memtx_tree_func_index_vtab;
>> >- } else if (def->key_def->is_multikey) {
>> >- vtab = &memtx_tree_index_multikey_vtab;
>> >- } else {
>> >- vtab = &memtx_tree_index_vtab;
>> >- }
>> >  if (index_create(&index->base, (struct engine *)memtx,
>> >  vtab, def) != 0) {
>> >  free(index);
>> >@@ -1524,3 +1701,23 @@ memtx_tree_index_new(struct memtx_engine *memtx, struct index_def *def)
>> >  memtx_index_extent_free, memtx);
>> >  return &index->base;
>> > }
>> >+
>> >+struct index *
>> >+memtx_tree_index_new(struct memtx_engine *memtx, struct index_def *def)
>> >+{
>> >+ const struct index_vtab *vtab;
>> >+ if (def->key_def->for_func_index) {
>> >+ if (def->key_def->func_index_func == NULL)
>> >+ vtab = &memtx_tree_disabled_index_vtab;
>> >+ else
>> >+ vtab = &memtx_tree_func_index_vtab;
>> >+ } else if (def->key_def->is_multikey) {
>> >+ vtab = &memtx_tree_index_multikey_vtab;
>> >+ } else if (def->opts.hint) {
>> >+ vtab = &memtx_tree_use_hint_index_vtab;
>> >+ } else {
>> >+ vtab = &memtx_tree_no_hint_index_vtab;
>> >+ return memtx_tree_index_new_tpl<0>(memtx, def, vtab);
>> >+ }
>> >+ return memtx_tree_index_new_tpl<1>(memtx, def, vtab);
>> >+}
>> >diff --git a/src/lib/salad/bps_tree.h b/src/lib/salad/bps_tree.h
>> >index ef5ae3d..0bb803a 100644
>> >--- a/src/lib/salad/bps_tree.h
>> >+++ b/src/lib/salad/bps_tree.h
>> >@@ -168,6 +168,17 @@
>> > 
>> > /* {{{ BPS-tree interface settings */
>> > /**
>> >+ * Optional namespace for structs and functions.
>> >+ * Is set, struct and functions will have BPS_TREE_NAMESPACE:: prefix.
>> >+ * For example one can #define BPS_TREE_NAMESPACE my along with
>> >+ * #define BPS_TREE_NAME _test, and use then
>> >+ * struct my::bps_tree_test my_tree;
>> >+ * my::bps_tree_test_create(&my_tree, ...);
>> >+ *
>> >+ * #define BPS_TREE_NAMESPACE
>> >+ */
>> >+
>> >+/**
>> >  * Custom name for structs and functions.
>> >  * Struct and functions will have bps_tree##BPS_TREE_NAME name or prefix.
>> >  * For example one can #define BPS_TREE_NAME _test, and use then
>> >@@ -300,6 +311,10 @@
>> > 
>> > /* }}} */
>> > 
>> >+#ifdef BPS_TREE_NAMESPACE
>> >+namespace BPS_TREE_NAMESPACE {
>> >+#endif
>> >+
>> > /* {{{ BPS-tree internal settings */
>> > typedef int16_t bps_tree_pos_t;
>> > typedef uint32_t bps_tree_block_id_t;
>> >@@ -6188,3 +6203,7 @@ bps_tree_debug_check_internal_functions(bool assertme)
>> > #undef bps_tree_debug_check_insert_and_move_to_left_inner
>> > 
>> > /* }}} */
>> >+
>> >+#ifdef BPS_TREE_NAMESPACE
>> >+} /* namespace BPS_TREE_NAMESPACE { */
>> >+#endif
>> >diff --git a/test/box/alter.result b/test/box/alter.result
>> >index 237c2d8..5b412a7 100644
>> >--- a/test/box/alter.result
>> >+++ b/test/box/alter.result
>> >@@ -680,8 +680,9 @@ s.index.pk
>> >   - type: unsigned
>> >     is_nullable: false
>> >     fieldno: 2
>> >- type: TREE
>> >+ hint: true
>> >   id: 0
>> >+ type: TREE
>> >   space_id: 731
>> >   name: pk
>> > ...
>> >@@ -710,9 +711,10 @@ s.index.pk
>> >   - type: unsigned
>> >     is_nullable: false
>> >     fieldno: 1
>> >- space_id: 731
>> >+ hint: true
>> >   id: 0
>> >   type: TREE
>> >+ space_id: 731
>> >   name: pk
>> > ...
>> > s.index.secondary
>> >@@ -722,8 +724,9 @@ s.index.secondary
>> >   - type: unsigned
>> >     is_nullable: false
>> >     fieldno: 2
>> >- type: TREE
>> >+ hint: true
>> >   id: 1
>> >+ type: TREE
>> >   space_id: 731
>> >   name: secondary
>> > ...
>> >@@ -1559,3 +1562,97 @@ assert(err:match('does not exist') ~= nil)
>> > ---
>> > - true
>> > ...
>> >+-- hint
>> >+s = box.schema.create_space('test');
>> >+---
>> >+...
>> >+s:create_index('test1', {type='tree', parts={{1, 'uint'}}}).hint
>> >+---
>> >+- true
>> >+...
>> >+s:create_index('test2', {type='tree', parts={{2, 'uint'}}, hint = true}).hint
>> >+---
>> >+- true
>> >+...
>> >+s:create_index('test3', {type='tree', parts={{3, 'uint'}}, hint = false}).hint
>> >+---
>> >+- false
>> >+...
>> >+s:create_index('test4', {type='tree', parts={{4, 'string'}}, hint = false}).hint
>> >+---
>> >+- false
>> >+...
>> >+s.index.test1.hint
>> >+---
>> >+- true
>> >+...
>> >+s.index.test2.hint
>> >+---
>> >+- true
>> >+...
>> >+s.index.test3.hint
>> >+---
>> >+- false
>> >+...
>> >+s.index.test4.hint
>> >+---
>> >+- false
>> >+...
>> >+N = 1000 box.begin() for i = 1,N do s:replace{i, i, i, '' .. i} end box.commit()
>> >+---
>> >+...
>> >+s.index.test1:bsize() == s.index.test2:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s.index.test1:bsize() > s.index.test3:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s.index.test1:bsize() > s.index.test4:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s.index.test1:alter{hint=false}
>> >+---
>> >+...
>> >+s.index.test2:alter{hint=true}
>> >+---
>> >+...
>> >+s.index.test3:alter{name='test33', hint=false}
>> >+---
>> >+...
>> >+s.index.test4:alter{hint=true}
>> >+---
>> >+...
>> >+s.index.test1.hint
>> >+---
>> >+- false
>> >+...
>> >+s.index.test2.hint
>> >+---
>> >+- true
>> >+...
>> >+s.index.test33.hint
>> >+---
>> >+- false
>> >+...
>> >+s.index.test4.hint
>> >+---
>> >+- true
>> >+...
>> >+s.index.test1:bsize() < s.index.test2:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s.index.test1:bsize() == s.index.test33:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s.index.test1:bsize() < s.index.test4:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s:drop()
>> >+---
>> >+...
>> >diff --git a/test/box/alter.test.lua b/test/box/alter.test.lua
>> >index abd08e2..2114186 100644
>> >--- a/test/box/alter.test.lua
>> >+++ b/test/box/alter.test.lua
>> >@@ -620,3 +620,37 @@ s:drop()
>> > s:alter({})
>> > ok, err = pcall(box.schema.space.alter, s.id, {})
>> > assert(err:match('does not exist') ~= nil)
>> >+
>> >+-- hint
>> >+s = box.schema.create_space('test');
>> >+s:create_index('test1', {type='tree', parts={{1, 'uint'}}}).hint
>> >+s:create_index('test2', {type='tree', parts={{2, 'uint'}}, hint = true}).hint
>> >+s:create_index('test3', {type='tree', parts={{3, 'uint'}}, hint = false}).hint
>> >+s:create_index('test4', {type='tree', parts={{4, 'string'}}, hint = false}).hint
>> >+
>> >+s.index.test1.hint
>> >+s.index.test2.hint
>> >+s.index.test3.hint
>> >+s.index.test4.hint
>> >+
>> >+N = 1000 box.begin() for i = 1,N do s:replace{i, i, i, '' .. i} end box.commit()
>> >+
>> >+s.index.test1:bsize() == s.index.test2:bsize()
>> >+s.index.test1:bsize() > s.index.test3:bsize()
>> >+s.index.test1:bsize() > s.index.test4:bsize()
>> >+
>> >+s.index.test1:alter{hint=false}
>> >+s.index.test2:alter{hint=true}
>> >+s.index.test3:alter{name='test33', hint=false}
>> >+s.index.test4:alter{hint=true}
>> >+
>> >+s.index.test1.hint
>> >+s.index.test2.hint
>> >+s.index.test33.hint
>> >+s.index.test4.hint
>> >+
>> >+s.index.test1:bsize() < s.index.test2:bsize()
>> >+s.index.test1:bsize() == s.index.test33:bsize()
>> >+s.index.test1:bsize() < s.index.test4:bsize()
>> >+
>> >+s:drop()
>> >\ No newline at end of file
>> >diff --git a/test/box/errinj.result b/test/box/errinj.result
>> >index 613d22c..b8c2476 100644
>> >--- a/test/box/errinj.result
>> >+++ b/test/box/errinj.result
>> >@@ -1774,9 +1774,10 @@ rtreespace:create_index('pk', {if_not_exists = true})
>> >   - type: unsigned
>> >     is_nullable: false
>> >     fieldno: 1
>> >+ hint: true
>> >   id: 0
>> >- space_id: 512
>> >   type: TREE
>> >+ space_id: 512
>> >   name: pk
>> > ...
>> > rtreespace:create_index('target', {type='rtree', dimension = 3, parts={2, 'array'},unique = false, if_not_exists = true,})
>> >diff --git a/test/box/tree_pk.result b/test/box/tree_pk.result
>> >index df3c78b..18cb607 100644
>> >--- a/test/box/tree_pk.result
>> >+++ b/test/box/tree_pk.result
>> >@@ -852,3 +852,317 @@ box.internal.collation.drop('test')
>> > box.internal.collation.drop('test-ci')
>> > ---
>> > ...
>> >+-- hints
>> >+s = box.schema.space.create('test')
>> >+---
>> >+...
>> >+s:create_index('test', {type = 'tree', hint = 'true'} )
>> >+---
>> >+- error: Illegal parameters, options parameter 'hint' should be of type boolean
>> >+...
>> >+s:create_index('test', {type = 'hash', hint = true} )
>> >+---
>> >+- error: 'Can''t create or modify index ''test'' in space ''test'': hint is only reasonable
>> >+ with memtx tree index'
>> >+...
>> >+s:create_index('test', {type = 'hash'}):alter({hint = true})
>> >+---
>> >+- error: 'Can''t create or modify index ''test'' in space ''test'': hint is only reasonable
>> >+ with memtx tree index'
>> >+...
>> >+s:create_index('multikey', {hint = true, parts = {{2, 'int', path = '[*]'}}})
>> >+---
>> >+- error: 'Can''t create or modify index ''multikey'' in space ''test'': multikey index
>> >+ can''t use hints'
>> >+...
>> >+s:create_index('multikey', {parts = {{2, 'int', path = '[*]'}}}):alter({hint = true})
>> >+---
>> >+- error: 'Can''t create or modify index ''multikey'' in space ''test'': multikey index
>> >+ can''t use hints'
>> >+...
>> >+lua_code = [[function(tuple) return {tuple[1] + tuple[2]} end]]
>> >+---
>> >+...
>> >+box.schema.func.create('s', {body = lua_code, is_deterministic = true, is_sandboxed = true})
>> >+---
>> >+...
>> >+s:create_index('func', {hint = true, func = box.func.s.id, parts = {{1, 'unsigned'}}})
>> >+---
>> >+- error: 'Can''t create or modify index ''func'' in space ''test'': functional index
>> >+ can''t use hints'
>> >+...
>> >+s:drop()
>> >+---
>> >+...
>> >+s = box.schema.space.create('test', {engine = 'vinyl'})
>> >+---
>> >+...
>> >+s:create_index('test', {type = 'tree', hint = true} )
>> >+---
>> >+- error: 'Can''t create or modify index ''test'' in space ''test'': hint is only reasonable
>> >+ with memtx tree index'
>> >+...
>> >+s:drop()
>> >+---
>> >+...
>> >+-- numeric hints
>> >+s1 = box.schema.space.create('test1')
>> >+---
>> >+...
>> >+s1:create_index('test', {type = 'tree', hint = false}).hint
>> >+---
>> >+- false
>> >+...
>> >+s2 = box.schema.space.create('test2')
>> >+---
>> >+...
>> >+s2:create_index('test', {type = 'tree'}).hint
>> >+---
>> >+- true
>> >+...
>> >+N = 2000
>> >+---
>> >+...
>> >+box.begin() for i = 1,N do local v = math.random(10 * N) s1:replace{v} s2:replace{v} end box.commit()
>> >+---
>> >+...
>> >+s1:count() == s2:count()
>> >+---
>> >+- true
>> >+...
>> >+good = true r1 = s1:select{} r2 = s2:select{}
>> >+---
>> >+...
>> >+if #r1 ~= #r2 then good = false end
>> >+---
>> >+...
>> >+for k,v in pairs(r1) do if r2[k][1] ~= v[1] then good = false end end
>> >+---
>> >+...
>> >+good
>> >+---
>> >+- true
>> >+...
>> >+r1 = nil r2 = nil
>> >+---
>> >+...
>> >+function diff(t1, t2) if t1 then return t1[1] ~= t2[1] else return t2 ~= nil end end
>> >+---
>> >+...
>> >+for i = 1, N * 10 do if diff(s1:get{i}, s2:get{i}) then good = false end end
>> >+---
>> >+...
>> >+good
>> >+---
>> >+- true
>> >+...
>> >+s1.index[0]:bsize() < s2.index[0]:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s1.index[0]:alter{hint=true}
>> >+---
>> >+...
>> >+s1.index[0]:bsize() == s2.index[0]:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s2.index[0]:alter{hint=false}
>> >+---
>> >+...
>> >+s1.index[0]:bsize() > s2.index[0]:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s1.index[0]:alter{hint=false}
>> >+---
>> >+...
>> >+s1.index[0]:bsize() == s2.index[0]:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s1:drop()
>> >+---
>> >+...
>> >+s2:drop()
>> >+---
>> >+...
>> >+-- string hints
>> >+s1 = box.schema.space.create('test1')
>> >+---
>> >+...
>> >+s1:create_index('test', {type = 'tree', parts = {1, 'str'}, hint = false}).hint
>> >+---
>> >+- false
>> >+...
>> >+s2 = box.schema.space.create('test2')
>> >+---
>> >+...
>> >+s2:create_index('test', {type = 'tree', parts = {1, 'str'}}).hint
>> >+---
>> >+- true
>> >+...
>> >+N = 1000
>> >+---
>> >+...
>> >+box.begin() for i = 1,N do local v = ''..math.random(10 * N) s1:replace{v} s2:replace{v} end box.commit()
>> >+---
>> >+...
>> >+s1:count() == s2:count()
>> >+---
>> >+- true
>> >+...
>> >+good = true r1 = s1:select{} r2 = s2:select{}
>> >+---
>> >+...
>> >+if #r1 ~= #r2 then good = false end
>> >+---
>> >+...
>> >+for k,v in pairs(r1) do if r2[k][1] ~= v[1] then good = false end end
>> >+---
>> >+...
>> >+good
>> >+---
>> >+- true
>> >+...
>> >+r1 = nil r2 = nil
>> >+---
>> >+...
>> >+function diff(t1, t2) if t1 then return t1[1] ~= t2[1] else return t2 ~= nil end end
>> >+---
>> >+...
>> >+for i = 1, N * 10 do v = ''..i if diff(s1:get{v}, s2:get{v}) then good = false end end
>> >+---
>> >+...
>> >+good
>> >+---
>> >+- true
>> >+...
>> >+s1.index[0]:bsize() < s2.index[0]:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s1.index[0]:alter{hint=true}
>> >+---
>> >+...
>> >+s1.index[0]:bsize() == s2.index[0]:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s2.index[0]:alter{hint=false}
>> >+---
>> >+...
>> >+s1.index[0]:bsize() > s2.index[0]:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s1.index[0]:alter{hint=false}
>> >+---
>> >+...
>> >+s1.index[0]:bsize() == s2.index[0]:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s1:drop()
>> >+---
>> >+...
>> >+s2:drop()
>> >+---
>> >+...
>> >+-- string with collation hints
>> >+s1 = box.schema.space.create('test1')
>> >+---
>> >+...
>> >+s1:create_index('test', {type = 'tree', parts = {{1, 'str', collation = 'Unicode'}}, hint = false}).hint
>> >+---
>> >+- false
>> >+...
>> >+s2 = box.schema.space.create('test2')
>> >+---
>> >+...
>> >+s2:create_index('test', {type = 'tree', parts = {{1, 'str', collation = 'Unicode'}}}).hint
>> >+---
>> >+- true
>> >+...
>> >+N = 1000
>> >+---
>> >+...
>> >+syms = {'a', 'B', 'c', 'D', 'ж', 'Ё', '~', '1', '%', '2'}
>> >+---
>> >+...
>> >+syms_size = #syms
>> >+---
>> >+...
>> >+len = 20
>> >+---
>> >+...
>> >+vals = {}
>> >+---
>> >+...
>> >+for i = 1,2*N do str = '' for j=1,len do str = str .. syms[math.random(syms_size)] end vals[i] = str end
>> >+---
>> >+...
>> >+for i = 1,N do local v = vals[i] s1:replace{v} s2:replace{v} end
>> >+---
>> >+...
>> >+s1:count() == s2:count()
>> >+---
>> >+- true
>> >+...
>> >+good = true r1 = s1:select{} r2 = s2:select{}
>> >+---
>> >+...
>> >+if #r1 ~= #r2 then good = false end
>> >+---
>> >+...
>> >+for k,v in pairs(r1) do if r2[k][1] ~= v[1] then good = false end end
>> >+---
>> >+...
>> >+good
>> >+---
>> >+- true
>> >+...
>> >+r1 = nil r2 = nil
>> >+---
>> >+...
>> >+function diff(t1, t2) if t1 then return t1[1] ~= t2[1] else return t2 ~= nil end end
>> >+---
>> >+...
>> >+for i = 1, N * 2 do v = vals[i] if diff(s1:get{v}, s2:get{v}) then good = false end end
>> >+---
>> >+...
>> >+good
>> >+---
>> >+- true
>> >+...
>> >+s1.index[0]:bsize() < s2.index[0]:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s1.index[0]:alter{hint=true}
>> >+---
>> >+...
>> >+s1.index[0]:bsize() == s2.index[0]:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s2.index[0]:alter{hint=false}
>> >+---
>> >+...
>> >+s1.index[0]:bsize() > s2.index[0]:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s1.index[0]:alter{hint=false}
>> >+---
>> >+...
>> >+s1.index[0]:bsize() == s2.index[0]:bsize()
>> >+---
>> >+- true
>> >+...
>> >+s1:drop()
>> >+---
>> >+...
>> >+s2:drop()
>> >+---
>> >+...
>> >diff --git a/test/box/tree_pk.test.lua b/test/box/tree_pk.test.lua
>> >index 1190ab4..2f22ed9 100644
>> >--- a/test/box/tree_pk.test.lua
>> >+++ b/test/box/tree_pk.test.lua
>> >@@ -301,3 +301,118 @@ s:drop()
>> > 
>> > box.internal.collation.drop('test')
>> > box.internal.collation.drop('test-ci')
>> >+
>> >+-- hints
>> >+s = box.schema.space.create('test')
>> >+s:create_index('test', {type = 'tree', hint = 'true'} )
>> >+s:create_index('test', {type = 'hash', hint = true} )
>> >+s:create_index('test', {type = 'hash'}):alter({hint = true})
>> >+s:create_index('multikey', {hint = true, parts = {{2, 'int', path = '[*]'}}})
>> >+s:create_index('multikey', {parts = {{2, 'int', path = '[*]'}}}):alter({hint = true})
>> >+lua_code = [[function(tuple) return {tuple[1] + tuple[2]} end]]
>> >+box.schema.func.create('s', {body = lua_code, is_deterministic = true, is_sandboxed = true})
>> >+s:create_index('func', {hint = true, func = box.func.s.id, parts = {{1, 'unsigned'}}})
>> >+s:drop()
>> >+
>> >+s = box.schema.space.create('test', {engine = 'vinyl'})
>> >+s:create_index('test', {type = 'tree', hint = true} )
>> >+s:drop()
>> >+
>> >+-- numeric hints
>> >+s1 = box.schema.space.create('test1')
>> >+s1:create_index('test', {type = 'tree', hint = false}).hint
>> >+s2 = box.schema.space.create('test2')
>> >+s2:create_index('test', {type = 'tree'}).hint
>> >+
>> >+N = 2000
>> >+box.begin() for i = 1,N do local v = math.random(10 * N) s1:replace{v} s2:replace{v} end box.commit()
>> >+s1:count() == s2:count()
>> >+
>> >+good = true r1 = s1:select{} r2 = s2:select{}
>> >+if #r1 ~= #r2 then good = false end
>> >+for k,v in pairs(r1) do if r2[k][1] ~= v[1] then good = false end end
>> >+good
>> >+r1 = nil r2 = nil
>> >+
>> >+function diff(t1, t2) if t1 then return t1[1] ~= t2[1] else return t2 ~= nil end end
>> >+for i = 1, N * 10 do if diff(s1:get{i}, s2:get{i}) then good = false end end
>> >+good
>> >+
>> >+s1.index[0]:bsize() < s2.index[0]:bsize()
>> >+s1.index[0]:alter{hint=true}
>> >+s1.index[0]:bsize() == s2.index[0]:bsize()
>> >+s2.index[0]:alter{hint=false}
>> >+s1.index[0]:bsize() > s2.index[0]:bsize()
>> >+s1.index[0]:alter{hint=false}
>> >+s1.index[0]:bsize() == s2.index[0]:bsize()
>> >+
>> >+s1:drop()
>> >+s2:drop()
>> >+
>> >+-- string hints
>> >+s1 = box.schema.space.create('test1')
>> >+s1:create_index('test', {type = 'tree', parts = {1, 'str'}, hint = false}).hint
>> >+s2 = box.schema.space.create('test2')
>> >+s2:create_index('test', {type = 'tree', parts = {1, 'str'}}).hint
>> >+
>> >+N = 1000
>> >+box.begin() for i = 1,N do local v = ''..math.random(10 * N) s1:replace{v} s2:replace{v} end box.commit()
>> >+s1:count() == s2:count()
>> >+
>> >+good = true r1 = s1:select{} r2 = s2:select{}
>> >+if #r1 ~= #r2 then good = false end
>> >+for k,v in pairs(r1) do if r2[k][1] ~= v[1] then good = false end end
>> >+good
>> >+r1 = nil r2 = nil
>> >+
>> >+function diff(t1, t2) if t1 then return t1[1] ~= t2[1] else return t2 ~= nil end end
>> >+for i = 1, N * 10 do v = ''..i if diff(s1:get{v}, s2:get{v}) then good = false end end
>> >+good
>> >+
>> >+s1.index[0]:bsize() < s2.index[0]:bsize()
>> >+s1.index[0]:alter{hint=true}
>> >+s1.index[0]:bsize() == s2.index[0]:bsize()
>> >+s2.index[0]:alter{hint=false}
>> >+s1.index[0]:bsize() > s2.index[0]:bsize()
>> >+s1.index[0]:alter{hint=false}
>> >+s1.index[0]:bsize() == s2.index[0]:bsize()
>> >+
>> >+s1:drop()
>> >+s2:drop()
>> >+
>> >+-- string with collation hints
>> >+s1 = box.schema.space.create('test1')
>> >+s1:create_index('test', {type = 'tree', parts = {{1, 'str', collation = 'Unicode'}}, hint = false}).hint
>> >+s2 = box.schema.space.create('test2')
>> >+s2:create_index('test', {type = 'tree', parts = {{1, 'str', collation = 'Unicode'}}}).hint
>> >+
>> >+N = 1000
>> >+syms = {'a', 'B', 'c', 'D', 'ж', 'Ё', '~', '1', '%', '2'}
>> >+syms_size = #syms
>> >+len = 20
>> >+vals = {}
>> >+for i = 1,2*N do str = '' for j=1,len do str = str .. syms[math.random(syms_size)] end vals[i] = str end
>> >+
>> >+for i = 1,N do local v = vals[i] s1:replace{v} s2:replace{v} end
>> >+s1:count() == s2:count()
>> >+
>> >+good = true r1 = s1:select{} r2 = s2:select{}
>> >+if #r1 ~= #r2 then good = false end
>> >+for k,v in pairs(r1) do if r2[k][1] ~= v[1] then good = false end end
>> >+good
>> >+r1 = nil r2 = nil
>> >+
>> >+function diff(t1, t2) if t1 then return t1[1] ~= t2[1] else return t2 ~= nil end end
>> >+for i = 1, N * 2 do v = vals[i] if diff(s1:get{v}, s2:get{v}) then good = false end end
>> >+good
>> >+
>> >+s1.index[0]:bsize() < s2.index[0]:bsize()
>> >+s1.index[0]:alter{hint=true}
>> >+s1.index[0]:bsize() == s2.index[0]:bsize()
>> >+s2.index[0]:alter{hint=false}
>> >+s1.index[0]:bsize() > s2.index[0]:bsize()
>> >+s1.index[0]:alter{hint=false}
>> >+s1.index[0]:bsize() == s2.index[0]:bsize()
>> >+
>> >+s1:drop()
>> >+s2:drop()
>> >diff --git a/test/box/tree_pk_multipart.result b/test/box/tree_pk_multipart.result
>> >index 93219f6..3f6bb94 100644
>> >--- a/test/box/tree_pk_multipart.result
>> >+++ b/test/box/tree_pk_multipart.result
>> >@@ -542,3 +542,156 @@ space:drop()
>> > space = nil
>> > ---
>> > ...
>> >+-- hints
>> >+test_run:cmd("setopt delimiter ';'")
>> >+---
>> >+- true
>> >+...
>> >+function equal(res1, res2)
>> >+ if #res1 ~= #res2 then
>> >+ return false
>> >+ end
>> >+ for k,v in pairs(res1) do
>> >+ if res2[k][1] ~= v[1] or res2[k][2] ~= v[2] then
>> >+ return false
>> >+ end
>> >+ end
>> >+ return true
>> >+end
>> >+test_run:cmd("setopt delimiter ''");
>> >+---
>> >+...
>> >+-- num num
>> >+N1 = 100
>> >+---
>> >+...
>> >+t1 = {}
>> >+---
>> >+...
>> >+for i = 1,N1*2 do t1[i] = math.random(10000) * 10000 + i end
>> >+---
>> >+...
>> >+N2 = 5
>> >+---
>> >+...
>> >+t2 = {}
>> >+---
>> >+...
>> >+for i = 1,N2*2 do t2[i] = math.random(1000000) end
>> >+---
>> >+...
>> >+s1 = box.schema.space.create('test1')
>> >+---
>> >+...
>> >+s1:create_index('test', {type = 'tree', parts = {{1, 'num'}, {2, 'num'}}, hint = false}).hint
>> >+---
>> >+- false
>> >+...
>> >+s2 = box.schema.space.create('test2')
>> >+---
>> >+...
>> >+s2:create_index('test', {type = 'tree', parts = {{1, 'num'}, {2, 'num'}}, hint = true}).hint
>> >+---
>> >+- true
>> >+...
>> >+for j = 1,N2 do for i = 1,N1 do s1:replace{t1[i], t2[j]} s2:replace{t1[i], t2[j]} end end
>> >+---
>> >+...
>> >+s1:count() == s2:count()
>> >+---
>> >+- true
>> >+...
>> >+equal(s1:select{}, s2:select{})
>> >+---
>> >+- true
>> >+...
>> >+good = true
>> >+---
>> >+...
>> >+for i = 1,N1*2 do good = good and equal(s1:select{t1[i]}, s2:select{t1[i]}) end
>> >+---
>> >+...
>> >+good
>> >+---
>> >+- true
>> >+...
>> >+for i = 1,N1*2 do for j=1,N2*2 do good = good and equal(s1:select{t1[i], t2[j]}, s2:select{t1[i], t2[j]}) end end
>> >+---
>> >+...
>> >+good
>> >+---
>> >+- true
>> >+...
>> >+s1:drop()
>> >+---
>> >+...
>> >+s2:drop()
>> >+---
>> >+...
>> >+-- str num
>> >+N1 = 100
>> >+---
>> >+...
>> >+t1 = {}
>> >+---
>> >+...
>> >+for i = 1,N1*2 do t1[i] = ''..(math.random(10000) * 10000 + i) end
>> >+---
>> >+...
>> >+N2 = 5
>> >+---
>> >+...
>> >+t2 = {}
>> >+---
>> >+...
>> >+for i = 1,N2*2 do t2[i] = math.random(1000000) end
>> >+---
>> >+...
>> >+s1 = box.schema.space.create('test1')
>> >+---
>> >+...
>> >+s1:create_index('test', {type = 'tree', parts = {{1, 'str'}, {2, 'num'}}, hint = false}).hint
>> >+---
>> >+- false
>> >+...
>> >+s2 = box.schema.space.create('test2')
>> >+---
>> >+...
>> >+s2:create_index('test', {type = 'tree', parts = {{1, 'str'}, {2, 'num'}}, hint = true}).hint
>> >+---
>> >+- true
>> >+...
>> >+for j = 1,N2 do for i = 1,N1 do s1:replace{t1[i], t2[j]} s2:replace{t1[i], t2[j]} end end
>> >+---
>> >+...
>> >+s1:count() == s2:count()
>> >+---
>> >+- true
>> >+...
>> >+equal(s1:select{}, s2:select{})
>> >+---
>> >+- true
>> >+...
>> >+good = true
>> >+---
>> >+...
>> >+for i = 1,N1*2 do good = good and equal(s1:select{t1[i]}, s2:select{t1[i]}) end
>> >+---
>> >+...
>> >+good
>> >+---
>> >+- true
>> >+...
>> >+for i = 1,N1*2 do for j=1,N2*2 do good = good and equal(s1:select{t1[i], t2[j]}, s2:select{t1[i], t2[j]}) end end
>> >+---
>> >+...
>> >+good
>> >+---
>> >+- true
>> >+...
>> >+s1:drop()
>> >+---
>> >+...
>> >+s2:drop()
>> >+---
>> >+...
>> >diff --git a/test/box/tree_pk_multipart.test.lua b/test/box/tree_pk_multipart.test.lua
>> >index 7d3405f..cba3a98 100644
>> >--- a/test/box/tree_pk_multipart.test.lua
>> >+++ b/test/box/tree_pk_multipart.test.lua
>> >@@ -194,3 +194,67 @@ test_run:cmd("setopt delimiter ''");
>> > space:drop()
>> > 
>> > space = nil
>> >+
>> >+
>> >+-- hints
>> >+test_run:cmd("setopt delimiter ';'")
>> >+function equal(res1, res2)
>> >+ if #res1 ~= #res2 then
>> >+ return false
>> >+ end
>> >+ for k,v in pairs(res1) do
>> >+ if res2[k][1] ~= v[1] or res2[k][2] ~= v[2] then
>> >+ return false
>> >+ end
>> >+ end
>> >+ return true
>> >+end
>> >+test_run:cmd("setopt delimiter ''");
>> >+
>> >+-- num num
>> >+N1 = 100
>> >+t1 = {}
>> >+for i = 1,N1*2 do t1[i] = math.random(10000) * 10000 + i end
>> >+N2 = 5
>> >+t2 = {}
>> >+for i = 1,N2*2 do t2[i] = math.random(1000000) end
>> >+
>> >+s1 = box.schema.space.create('test1')
>> >+s1:create_index('test', {type = 'tree', parts = {{1, 'num'}, {2, 'num'}}, hint = false}).hint
>> >+s2 = box.schema.space.create('test2')
>> >+s2:create_index('test', {type = 'tree', parts = {{1, 'num'}, {2, 'num'}}, hint = true}).hint
>> >+for j = 1,N2 do for i = 1,N1 do s1:replace{t1[i], t2[j]} s2:replace{t1[i], t2[j]} end end
>> >+s1:count() == s2:count()
>> >+equal(s1:select{}, s2:select{})
>> >+good = true
>> >+for i = 1,N1*2 do good = good and equal(s1:select{t1[i]}, s2:select{t1[i]}) end
>> >+good
>> >+for i = 1,N1*2 do for j=1,N2*2 do good = good and equal(s1:select{t1[i], t2[j]}, s2:select{t1[i], t2[j]}) end end
>> >+good
>> >+
>> >+s1:drop()
>> >+s2:drop()
>> >+
>> >+-- str num
>> >+N1 = 100
>> >+t1 = {}
>> >+for i = 1,N1*2 do t1[i] = ''..(math.random(10000) * 10000 + i) end
>> >+N2 = 5
>> >+t2 = {}
>> >+for i = 1,N2*2 do t2[i] = math.random(1000000) end
>> >+
>> >+s1 = box.schema.space.create('test1')
>> >+s1:create_index('test', {type = 'tree', parts = {{1, 'str'}, {2, 'num'}}, hint = false}).hint
>> >+s2 = box.schema.space.create('test2')
>> >+s2:create_index('test', {type = 'tree', parts = {{1, 'str'}, {2, 'num'}}, hint = true}).hint
>> >+for j = 1,N2 do for i = 1,N1 do s1:replace{t1[i], t2[j]} s2:replace{t1[i], t2[j]} end end
>> >+s1:count() == s2:count()
>> >+equal(s1:select{}, s2:select{})
>> >+good = true
>> >+for i = 1,N1*2 do good = good and equal(s1:select{t1[i]}, s2:select{t1[i]}) end
>> >+good
>> >+for i = 1,N1*2 do for j=1,N2*2 do good = good and equal(s1:select{t1[i], t2[j]}, s2:select{t1[i], t2[j]}) end end
>> >+good
>> >+
>> >+s1:drop()
>> >+s2:drop()
>> >--
>> >2.7.4
>> > 
>> --
>> Ilya Kosarev
--
Ilya Kosarev