MDEV-33281 Implement optimizer hints

    This commit introduces:
    - the infrastructure for optimizer hints;
    - hints for join buffering: BNL(), NO_BNL(), BKA(), NO_BKA();
    - NO_ICP() hint for disabling index condition pushdown;
    - MRR(), MO_MRR() hint for multi-range reads control;
    - NO_RANGE_OPTIMIZATION() for disabling range optimization;
    - QB_NAME() for assigning names for query blocks.

Author: Olernov

libmysqld/CMakeLists.txt

@@ -160,6 +160,7 @@ SET(SQL_EMBEDDED_SOURCES emb_qcache.cc libmysqld.c lib_sql.cc
            ../sql/sp_cursor.cc
            ../sql/opt_hints_parser.cc ../sql/opt_hints_parser.h
            ../sql/scan_char.h
+           ../sql/opt_hints.cc ../sql/opt_hints.h
            ${GEN_SOURCES}
            ${MYSYS_LIBWRAP_SOURCE}
 )

mysql-test/main/opt_hints.result

@@ -139,7 +139,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t4	ref	y_idx	y_idx	5	const	1	100.00	
 1	SIMPLE	t5	range	x_idx	x_idx	5	NULL	2	100.00	Using where; Using join buffer (flat, BNL join)
 Warnings:
-Warning	4199	Unresolved name `t5`@`select#2` `z_idx` for NO_ICP hint
+Warning	4205	Unresolved index name `t5`@`select#2` `z_idx` for NO_ICP hint
 Note	1003	select /*+ NO_ICP(`t5`@`select#2` `y_idx`) NO_ICP(`t5`@`select#2` `x_idx`) */ `test`.`t4`.`x` AS `x`,`test`.`t5`.`y` AS `y` from `test`.`t4` join `test`.`t4` `t5` where `test`.`t4`.`y` = 8 and `test`.`t5`.`x` between 7 and <cache>(8 + 0)
 # ICP should still be used
 EXPLAIN EXTENDED SELECT * FROM
@@ -405,7 +405,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	
 1	SIMPLE	t2	ALL	f1	NULL	NULL	NULL	28	25.00	Using where; Using join buffer (flat, BNL join)
 Warnings:
-Warning	4198	Query block name `qb1` is not found for BKA hint
+Warning	4203	Query block name `qb1` is not found for BKA hint
 Note	1003	select /*+ QB_NAME(`qb1`) */ `test`.`t2`.`f1` AS `f1`,`test`.`t2`.`f2` AS `f2`,`test`.`t2`.`f3` AS `f3` from `test`.`t1` join `test`.`t2` where `test`.`t2`.`f1` = `test`.`t1`.`f1` and `test`.`t2`.`f2` between `test`.`t1`.`f1` and `test`.`t1`.`f2` and `test`.`t2`.`f2` + 1 >= `test`.`t1`.`f1` + 1
 # Should not crash
 PREPARE stmt1 FROM "SELECT /*+ BKA(t2) */ t2.f1, t2.f2, t2.f3 FROM t1,t2
@@ -449,9 +449,9 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	100.00	
 1	SIMPLE	t2	ALL	f1	NULL	NULL	NULL	28	25.00	Using where; Using join buffer (flat, BNL join)
 Warnings:
-Warning	4199	Unresolved name `t3`@`select#1` for BKA hint
-Warning	4199	Unresolved name `t3`@`select#1` for NO_RANGE_OPTIMIZATION hint
-Warning	4199	Unresolved name `t3`@`select#1` `idx1` for NO_RANGE_OPTIMIZATION hint
+Warning	4204	Unresolved table name `t3`@`select#1` for BKA hint
+Warning	4204	Unresolved table name `t3`@`select#1` for NO_RANGE_OPTIMIZATION hint
+Warning	4205	Unresolved index name `t3`@`select#1` `idx1` for NO_RANGE_OPTIMIZATION hint
 Note	1003	select /*+ BKA(`t2`@`select#1`) NO_BNL(`t1`@`select#1`) */ `test`.`t2`.`f1` AS `f1`,`test`.`t2`.`f2` AS `f2`,`test`.`t2`.`f3` AS `f3` from `test`.`t1` join `test`.`t2` where `test`.`t2`.`f1` = `test`.`t1`.`f1` and `test`.`t2`.`f2` between `test`.`t1`.`f1` and `test`.`t1`.`f2` and `test`.`t2`.`f2` + 1 >= `test`.`t1`.`f1` + 1
 # Check illegal syntax
 EXPLAIN EXTENDED SELECT /*+ BKA(qb1 t3@qb1) */ f2 FROM
@@ -488,7 +488,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	tbl12	ALL	NULL	NULL	NULL	NULL	10	100.00	Using where
 1	SIMPLE	tbl13	hash_ALL	a	#hash#a	5	test.tbl12.a	1000	0.10	Using where; Using join buffer (flat, BNLH join)
 Warnings:
-Warning	4199	Unresolved name `tbl2`@`select#1` for BKA hint
+Warning	4204	Unresolved table name `tbl2`@`select#1` for BKA hint
 Note	1003	select `test`.`tbl12`.`a` AS `a`,`test`.`tbl12`.`b` AS `b`,`test`.`tbl13`.`a` AS `a`,`test`.`tbl13`.`b` AS `b`,`test`.`tbl13`.`c` AS `c`,`test`.`tbl13`.`filler` AS `filler` from `test`.`t12` `tbl12` join `test`.`t13` `tbl13` where `test`.`tbl13`.`a` = `test`.`tbl12`.`a` and `test`.`tbl13`.`b` + 1 <= `test`.`tbl13`.`b` + 1
 # Check that PS and conventional statements give the same result.
 FLUSH STATUS;
@@ -930,19 +930,19 @@ SELECT /*+ BKA() BKA() */ 1;
 1
 1
 Warnings:
-Warning	4197	Hint BKA( ) is ignored as conflicting/duplicated
+Warning	4202	Hint BKA() is ignored as conflicting/duplicated
 SELECT /*+ BKA(t1) BKA(t1) */ * FROM t1;
 i
 Warnings:
-Warning	4197	Hint BKA(`t1` ) is ignored as conflicting/duplicated
+Warning	4202	Hint BKA(`t1`) is ignored as conflicting/duplicated
 SELECT /*+ QB_NAME(q1) BKA(t1@q1) BKA(t1@q1) */ * FROM t1;
 i
 Warnings:
-Warning	4197	Hint BKA(`t1`@`q1` ) is ignored as conflicting/duplicated
+Warning	4202	Hint BKA(`t1`@`q1`) is ignored as conflicting/duplicated
 SELECT /*+ QB_NAME(q1) NO_ICP(@q1 t1 PRIMARY) NO_ICP(@q1 t1 PRIMARY) */ * FROM t1;
 i
 Warnings:
-Warning	4197	Hint NO_ICP(`t1`@`q1` `PRIMARY` ) is ignored as conflicting/duplicated
+Warning	4202	Hint NO_ICP(`t1`@`q1` `PRIMARY`) is ignored as conflicting/duplicated
 DROP TABLE t1;
 # WL#8016 Parser for optimizer hints
 CREATE TABLE t1 (i INT, j INT);
@@ -955,12 +955,12 @@ SELECT /*+*/ 1;
 1
 1
 Warnings:
-Warning	1064	Optimizer hint syntax error near '*/' at line 1
+Warning	1064	Optimizer hint syntax error near '*/ 1' at line 1
 SELECT /*+ */ 1;
 1
 1
 Warnings:
-Warning	1064	Optimizer hint syntax error near '*/' at line 1
+Warning	1064	Optimizer hint syntax error near '*/ 1' at line 1
 SELECT /*+ * ** / // /* */ 1;
 1
 1
@@ -990,22 +990,22 @@ SELECT /*+ `@` */ 1;
 1
 1
 Warnings:
-Warning	1064	Optimizer hint syntax error near '@` */ 1' at line 1
+Warning	1064	Optimizer hint syntax error near '`@` */ 1' at line 1
 SELECT /*+ `@foo` */ 1;
 1
 1
 Warnings:
-Warning	1064	Optimizer hint syntax error near '@foo` */ 1' at line 1
+Warning	1064	Optimizer hint syntax error near '`@foo` */ 1' at line 1
 SELECT /*+ `foo@bar` */ 1;
 1
 1
 Warnings:
-Warning	1064	Optimizer hint syntax error near 'foo@bar` */ 1' at line 1
+Warning	1064	Optimizer hint syntax error near '`foo@bar` */ 1' at line 1
 SELECT /*+ `foo @bar` */ 1;
 1
 1
 Warnings:
-Warning	1064	Optimizer hint syntax error near 'foo @bar` */ 1' at line 1
+Warning	1064	Optimizer hint syntax error near '`foo @bar` */ 1' at line 1
 SELECT /*+ BKA( @) */ 1;
 1
 1
@@ -1020,7 +1020,7 @@ SELECT /*+ BKA(t1 @) */ 1;
 1
 1
 Warnings:
-Warning	1064	Optimizer hint syntax error near '@) */ 1' at line 1
+Warning	1064	Optimizer hint syntax error near ') */ 1' at line 1
 
 # We don't support "*/" inside quoted identifiers (syntax error):
 
@@ -1079,15 +1079,15 @@ Warning	1064	Optimizer hint syntax error near 'b) */   1 FROM t1 a, t1 b' at lin
 SELECT /*+ NO_ICP(i1) */ 1 FROM t1;
 1
 Warnings:
-Warning	4199	Unresolved name `i1`@`select#1` for NO_ICP hint
+Warning	4204	Unresolved table name `i1`@`select#1` for NO_ICP hint
 SELECT /*+ NO_ICP(i1 i2) */ 1 FROM t1;
 1
 Warnings:
-Warning	4199	Unresolved name `i1`@`select#1` `i2` for NO_ICP hint
+Warning	4205	Unresolved index name `i1`@`select#1` `i2` for NO_ICP hint
 SELECT /*+ NO_ICP(@qb ident) */ 1 FROM t1;
 1
 Warnings:
-Warning	4198	Query block name `qb` is not found for NO_ICP hint
+Warning	4203	Query block name `qb` is not found for NO_ICP hint
 
 # valid hint sequences, no warnings expected:
 
@@ -1142,12 +1142,12 @@ CREATE INDEX 3rd_index ON t1(i, j);
 SELECT /*+ NO_ICP(3rd_index) */ 1 FROM t1;
 1
 Warnings:
-Warning	4199	Unresolved name `3rd_index`@`select#1` for NO_ICP hint
+Warning	4204	Unresolved table name `3rd_index`@`select#1` for NO_ICP hint
 CREATE INDEX $index ON t1(j, i);
 SELECT /*+ NO_ICP($index) */ 1 FROM t1;
 1
 Warnings:
-Warning	4199	Unresolved name `$index`@`select#1` for NO_ICP hint
+Warning	4204	Unresolved table name `$index`@`select#1` for NO_ICP hint
 CREATE TABLE ` quoted name test` (i INT);
 SELECT /*+ BKA(` quoted name test`) */ 1 FROM t1;
 1
@@ -1184,7 +1184,7 @@ SET SQL_MODE = '';
 SELECT /*+ BKA(" quoted name test") */ 1 FROM t1;
 1
 Warnings:
-Warning	1064	Optimizer hint syntax error near '" quoted name test") */ 1 FROM t1' at line 1
+Warning	4204	Unresolved table name `" quoted name test"`@`select#1` for BKA hint
 DROP TABLE ` quoted name test`;
 DROP TABLE `test1``test2```;
 # Valid hints, no warning:
@@ -1228,11 +1228,11 @@ CREATE TABLE tableТ (i INT);
 SELECT /*+ BKA(tableТ) */ 1 FROM t1;
 1
 Warnings:
-Warning	4199	Unresolved name `tableТ`@`select#1` for BKA hint
+Warning	4204	Unresolved table name `tableТ`@`select#1` for BKA hint
 SELECT /*+ BKA(test@tableТ) */ 1 FROM t1;
 1
 Warnings:
-Warning	4198	Query block name `tableТ` is not found for BKA hint
+Warning	4203	Query block name `tableТ` is not found for BKA hint
 DROP TABLE tableТ;
 CREATE TABLE таблица (i INT);
 SELECT /*+ BKA(`таблица`) */ 1 FROM t1;
@@ -1242,11 +1242,11 @@ Warning	4199	Unresolved name `таблица`@`select#1` for BKA hint
 SELECT /*+ BKA(таблица) */ 1 FROM t1;
 1
 Warnings:
-Warning	4199	Unresolved name `таблица`@`select#1` for BKA hint
+Warning	4204	Unresolved table name `таблица`@`select#1` for BKA hint
 SELECT /*+ BKA(test@таблица) */ 1 FROM t1;
 1
 Warnings:
-Warning	4198	Query block name `таблица` is not found for BKA hint
+Warning	4203	Query block name `таблица` is not found for BKA hint
 SELECT /*+ NO_ICP(`\D1`) */ 1 FROM t1;
 1
 Warnings:
@@ -1287,12 +1287,12 @@ SELECT /*+ NO_ICP(10) */ 1;
 1
 1
 Warnings:
-Warning	1064	Optimizer hint syntax error near '10) */ 1' at line 1
+Warning	4204	Unresolved table name `10`@`select#1` for NO_ICP hint
 SELECT /*+ NO_ICP( */ 1;
 1
 1
 Warnings:
-Warning	1064	Optimizer hint syntax error near '*/' at line 1
+Warning	1064	Optimizer hint syntax error near '*/ 1' at line 1
 SELECT /*+ NO_ICP) */ 1;
 1
 1
@@ -1302,7 +1302,7 @@ SELECT /*+ NO_ICP(t1 */ 1;
 1
 1
 Warnings:
-Warning	1064	Optimizer hint syntax error near '*/' at line 1
+Warning	1064	Optimizer hint syntax error near '*/ 1' at line 1
 SELECT /*+ NO_ICP(t1 ( */ 1;
 1
 1
@@ -1347,7 +1347,7 @@ NO_ICP(@qb ident)
 1
 1
 Warnings:
-Warning	4198	Query block name `qb` is not found for NO_ICP hint
+Warning	4203	Query block name `qb` is not found for NO_ICP hint
 SELECT /*+
 ? bad syntax
 */ 1;

sql/CMakeLists.txt

@@ -194,6 +194,7 @@ SET (SQL_SOURCE
                opt_vcol_substitution.h
                opt_vcol_substitution.cc
                opt_hints_parser.cc opt_hints_parser.h scan_char.h
+               opt_hints.cc opt_hints.h
                ${CMAKE_CURRENT_BINARY_DIR}/lex_hash.h
                ${CMAKE_CURRENT_BINARY_DIR}/lex_token.h
                ${GEN_SOURCES}

sql/mem_root_array.h

@@ -43,6 +43,7 @@
           __has_trivial_destructor is supported by some (but not all)
           compilers we use.
 */
+
 template<typename Element_type, bool has_trivial_destructor>
 class Mem_root_array
 {
@@ -53,7 +54,6 @@ class Mem_root_array
   Mem_root_array(MEM_ROOT *root)
     : m_root(root), m_array(NULL), m_size(0), m_capacity(0)
   {
-    DBUG_ASSERT(m_root != NULL);
   }
 
   Mem_root_array(MEM_ROOT *root, size_t n, const value_type &val= value_type())
@@ -62,6 +62,20 @@ class Mem_root_array
     resize(n, val);
   }
 
+  Mem_root_array(const Mem_root_array& other)
+  {
+    do_copy_construct(other);
+  }
+
+  Mem_root_array &operator=(const Mem_root_array& other)
+  {
+    if(this != &other)
+    {
+      clear();
+      do_copy_construct(other);
+    }
+  }
+
   ~Mem_root_array()
   {
     clear();
@@ -231,14 +245,22 @@ class Mem_root_array
   const MEM_ROOT *mem_root() const { return m_root; }
 
 private:
-  MEM_ROOT *const m_root;
-  Element_type   *m_array;
-  size_t          m_size;
-  size_t          m_capacity;
-
-  // Not (yet) implemented.
-  Mem_root_array(const Mem_root_array&);
-  Mem_root_array &operator=(const Mem_root_array&);
+  MEM_ROOT       *m_root;
+  Element_type   *m_array= nullptr;
+  size_t          m_size= 0;
+  size_t          m_capacity= 0;
+
+  void do_copy_construct(const Mem_root_array& other)
+  {
+    m_root= other.m_root;
+    reserve(other.size());
+    for (size_t ix= 0; ix < other.size(); ++ix)
+    {
+      Element_type *p= &m_array[ix];
+      new (p) Element_type(other[ix]);
+    }
+    m_size= other.m_size;
+  }
 };
 
 

sql/multi_range_read.cc

@@ -21,6 +21,7 @@
 #include "sql_statistics.h"
 #include "rowid_filter.h"
 #include "optimizer_defaults.h"
+#include "opt_hints.h"
 
 static void get_sweep_read_cost(TABLE *table, ha_rows nrows, bool interrupted,
                                 Cost_estimate *cost);
@@ -1148,7 +1149,9 @@ int DsMrr_impl::dsmrr_init(handler *h_arg, RANGE_SEQ_IF *seq_funcs,
   buf_manager.reset_buffer_sizes= do_nothing;
   buf_manager.redistribute_buffer_space= do_nothing;
 
-  if (mode & (HA_MRR_USE_DEFAULT_IMPL | HA_MRR_SORTED))
+  if (!hint_key_state(thd, table, h_arg->active_index,
+                      MRR_HINT_ENUM, OPTIMIZER_SWITCH_MRR) ||
+      mode & (HA_MRR_USE_DEFAULT_IMPL | HA_MRR_SORTED))
     goto use_default_impl;
 
   /*
@@ -1901,10 +1904,16 @@ bool DsMrr_impl::choose_mrr_impl(uint keyno, ha_rows rows, uint *flags,
   THD *thd= primary_file->get_table()->in_use;
   TABLE_SHARE *share= primary_file->get_table_share();
 
+  const bool mrr_on= hint_key_state(thd, table, keyno, MRR_HINT_ENUM,
+                                    OPTIMIZER_SWITCH_MRR);
+  const bool force_dsmrr_by_hints=
+    hint_key_state(thd, table, keyno, MRR_HINT_ENUM, 0) ||
+    hint_table_state(thd, table, BKA_HINT_ENUM, 0);
+
   bool doing_cpk_scan= check_cpk_scan(thd, share, keyno, *flags); 
   bool using_cpk= primary_file->is_clustering_key(keyno);
   *flags &= ~HA_MRR_IMPLEMENTATION_FLAGS;
-  if (!optimizer_flag(thd, OPTIMIZER_SWITCH_MRR) ||
+  if (!(mrr_on || force_dsmrr_by_hints) ||
       *flags & HA_MRR_INDEX_ONLY ||
       (using_cpk && !doing_cpk_scan) || key_uses_partial_cols(share, keyno))
   {
@@ -1919,15 +1928,17 @@ bool DsMrr_impl::choose_mrr_impl(uint keyno, ha_rows rows, uint *flags,
                               &dsmrr_cost))
     return TRUE;
 
-  bool force_dsmrr;
   /* 
     If mrr_cost_based flag is not set, then set cost of DS-MRR to be minimum of
     DS-MRR and Default implementations cost. This allows one to force use of
     DS-MRR whenever it is applicable without affecting other cost-based
-    choices.
+    choices. Note that if MRR or BKA hint is
+    specified, DS-MRR will be used regardless of cost.
   */
-  if ((force_dsmrr= !optimizer_flag(thd, OPTIMIZER_SWITCH_MRR_COST_BASED)) &&
-      dsmrr_cost.total_cost() > cost->total_cost())
+  const bool force_dsmrr=
+    (force_dsmrr_by_hints ||
+     !optimizer_flag(thd, OPTIMIZER_SWITCH_MRR_COST_BASED));
+  if (force_dsmrr && dsmrr_cost.total_cost() > cost->total_cost())
     dsmrr_cost= *cost;
 
   if (force_dsmrr || dsmrr_cost.total_cost() <= cost->total_cost())