Mirrors
/
mariadb
mirror of https://github.com/MariaDB/server
3
0
Fork 0
Code Releases Activity
Browse Source

MDEV-33281 Make BNL() hint enable hashed join buffers 

Since BNL() hint does not specify which whether hashed or non-hashed
join cache should be employed, allow usage of hashed ones
where possible
pull/3878/head
Oleg Smirnov 11 months ago
parent
67319f3e8d
commit
af14196b8a
7 changed files with 69 additions and 67 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 18
      mysql-test/main/opt_hints.result
  2. 12
      mysql-test/main/opt_hints.test
  3. 2
      sql/multi_range_read.cc
  4. 18
      sql/opt_hints.cc
  5. 20
      sql/opt_hints.h
  6. 60
      sql/sql_select.cc
  7. 6
      sql/sql_select.h

18
mysql-test/main/opt_hints.result
View File

@ -1135,6 +1135,24 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 0 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 ALL NULL NULL NULL NULL 0 Using where; Using join buffer (incremental, BNL join)
1 SIMPLE t4 ALL NULL NULL NULL NULL 0 Using where; Using join buffer (incremental, BNL join)
set join_cache_level=8;
INSERT INTO t2 VALUES (1), (2), (null), (1);
# BNLH buffer is used when allowed by JCL setting
EXPLAIN SELECT * FROM t1, t2 WHERE t1.a=t2.a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 4 Using where
1 SIMPLE t2 hash_ALL NULL #hash#$hj 5 test.t1.a 4 Using where; Using join buffer (flat, BNLH join)
# Make sure the hint enables BNL even when JCL=0:
set join_cache_level=0;
EXPLAIN SELECT /*+BNL(t2) */ * FROM t1, t2 WHERE t1.a=t2.a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 4 Using where
1 SIMPLE t2 hash_ALL NULL #hash#$hj 5 test.t1.a 4 Using where; Using join buffer (flat, BNLH join)
set join_cache_level=2;
EXPLAIN SELECT /*+BNL(t2) */ * FROM t1, t2 WHERE t1.a=t2.a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 4 Using where
1 SIMPLE t2 hash_ALL NULL #hash#$hj 5 test.t1.a 4 Using where; Using join buffer (flat, BNLH join)
DROP TABLE t1,t2,t3,t4;
#
# Mix of BNL/BKA flat and incremental join buffers for OUTER JOINs

12
mysql-test/main/opt_hints.test
View File

@ -565,6 +565,18 @@ EXPLAIN SELECT /*+ BNL(t2, t3, t4)*/ t1.a
FROM t1 LEFT JOIN (t2 LEFT JOIN (t3 LEFT JOIN t4 ON 1) ON t2.a) ON 0
WHERE t1.a OR t4.a;
set join_cache_level=8;
INSERT INTO t2 VALUES (1), (2), (null), (1);
--echo # BNLH buffer is used when allowed by JCL setting
EXPLAIN SELECT * FROM t1, t2 WHERE t1.a=t2.a;
--echo # Make sure the hint enables BNL even when JCL=0:
set join_cache_level=0;
EXPLAIN SELECT /*+BNL(t2) */ * FROM t1, t2 WHERE t1.a=t2.a;
set join_cache_level=2;
EXPLAIN SELECT /*+BNL(t2) */ * FROM t1, t2 WHERE t1.a=t2.a;
DROP TABLE t1,t2,t3,t4;

2
sql/multi_range_read.cc
View File

@ -1908,7 +1908,7 @@ bool DsMrr_impl::choose_mrr_impl(uint keyno, ha_rows rows, uint *flags,
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);
hint_table_state(thd, table, BKA_HINT_ENUM, false);
bool doing_cpk_scan= check_cpk_scan(thd, share, keyno, *flags);
bool using_cpk= primary_file->is_clustering_key(keyno);

18
sql/opt_hints.cc
View File

@ -483,24 +483,6 @@ bool hint_key_state(const THD *thd, const TABLE *table,
bool hint_table_state(const THD *thd, const TABLE *table,
opt_hints_enum type_arg,
uint optimizer_switch)
{
TABLE_LIST *table_list= table->pos_in_table_list;
if (table_list->opt_hints_qb)
{
bool ret_val= false;
if (get_hint_state(table_list->opt_hints_table,
table_list->opt_hints_qb,
type_arg, &ret_val))
return ret_val;
}
return optimizer_flag(thd, optimizer_switch);
}
bool hint_table_state_or_fallback(const THD *thd, const TABLE *table,
opt_hints_enum type_arg,
bool fallback_value)
{

20
sql/opt_hints.h
View File

@ -543,21 +543,6 @@ bool hint_key_state(const THD *thd, const TABLE *table,
uint keyno, opt_hints_enum type_arg,
uint optimizer_switch);
/**
Returns table hint value if hint is specified, returns
optimizer switch value if hint is not specified.
@param thd Pointer to THD object
@param tab Pointer to TABLE object
@param type_arg Hint type
@param optimizer_switch Optimizer switch flag
@return table hint value if hint is specified,
otherwise optimizer switch value.
*/
bool hint_table_state(const THD *thd, const TABLE *table,
opt_hints_enum type_arg,
uint optimizer_switch);
/**
Returns table hint value if hint is specified, returns
@ -571,7 +556,6 @@ bool hint_table_state(const THD *thd, const TABLE *table,
@return table hint value if hint is specified,
otherwise fallback value.
*/
bool hint_table_state_or_fallback(const THD *thd, const TABLE *table,
opt_hints_enum type_arg,
bool fallback_value);
bool hint_table_state(const THD *thd, const TABLE *table,
opt_hints_enum type_arg, bool fallback_value);
#endif /* OPT_HINTS_INCLUDED */

60
sql/sql_select.cc
View File

@ -6662,7 +6662,7 @@ add_key_field(JOIN *join,
{
uint optimize= 0;
if (eq_func &&
((join->is_allowed_hash_join_access() &&
((join->is_allowed_hash_join_access(field->table) &&
field->hash_join_is_possible() &&
!(field->table->pos_in_table_list->is_materialized_derived() &&
field->table->is_created())) ||
@ -9428,8 +9428,7 @@ best_access_path(JOIN *join,
(2) s is inner table of outer join -> join cache is allowed for outer joins
*/
if (idx > join->const_tables && best.key == 0 &&
(join->allowed_join_cache_types & JOIN_CACHE_HASHED_BIT) &&
join->max_allowed_join_cache_level > 2 &&
join->is_allowed_hash_join_access(table) &&
!bitmap_is_clear_all(eq_join_set) && !disable_jbuf &&
(!s->emb_sj_nest ||
join->allowed_semijoin_with_cache) && // (1)
@ -11468,7 +11467,6 @@ get_costs_for_tables(JOIN *join, table_map remaining_tables, uint idx,
JOIN_TAB *s;
table_map found_tables= 0;
bool found_eq_ref= 0;
bool disable_jbuf= join->thd->variables.join_cache_level == 0;
DBUG_ENTER("get_plans_for_tables");
s= *pos;
@ -11485,6 +11483,11 @@ get_costs_for_tables(JOIN *join, table_map remaining_tables, uint idx,
sort_end->join_tab= pos;
sort_end->position= sort_position;
bool hint_forces_jbuf=
hint_table_state(join->thd, s->table, BNL_HINT_ENUM, false);
bool disable_jbuf=
(join->thd->variables.join_cache_level == 0) && !hint_forces_jbuf;
Json_writer_object wrapper(thd);
/* Find the best access method from 's' to the current partial plan */
@ -14471,11 +14474,17 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
add_cond_and_fix(thd, &tmp, tab->select_cond);
}
uint max_jcl= join->max_allowed_join_cache_level;
bool is_hash_allowed= join->allowed_join_cache_types &
JOIN_CACHE_HASHED_BIT;
bool is_bnlh_enabled= ((max_jcl == 3 || max_jcl == 4) &&
is_hash_allowed) ||
hint_table_state(thd, tab->table, BNL_HINT_ENUM, false);
bool is_bkah_enabled= (max_jcl > 4 && is_hash_allowed) ||
hint_table_state(thd, tab->table, BKA_HINT_ENUM, false);
is_hj= (tab->type == JT_REF || tab->type == JT_EQ_REF) &&
(join->allowed_join_cache_types & JOIN_CACHE_HASHED_BIT) &&
((join->max_allowed_join_cache_level+1)/2 == 2 ||
((join->max_allowed_join_cache_level+1)/2 > 2 &&
is_hash_join_key_no(tab->ref.key))) &&
(is_bnlh_enabled ||
(is_bkah_enabled && is_hash_join_key_no(tab->ref.key))) &&
(!tab->emb_sj_nest ||
join->allowed_semijoin_with_cache) &&
(!(tab->table->map & join->outer_join) ||
@ -15631,17 +15640,14 @@ end_sj_materialize(JOIN *join, JOIN_TAB *join_tab, bool end_of_records)
OPTIMIZER_HINTS
The following hints may influence the choice of join buffering:
BNL(t1,t2,..): enables BNL and BNLH buffers for the specified tables
when join_cache_level=0. Effectively it increases
when join_cache_level < 4. It effectively increases
join_cache_level to 4 for given tables.
NO_BNL(t1,t2,..): disables BNL/BNLH join buffers, which could have been
chosen for the specified tables otherwise. Does not
prevent employing of BKA/BKAH buffers
BKA(t1,t2,..): enables BKA and BKAH buffers for the specified tables
when optimizer switch join_cache_bka=off. Does not
increase join_cache_level, i.e., when join_cache_level=4
and the hint is specified, BKA join buffers will still
not be employed. The hint effectively overrides only
optimizer switch join_cache_bka setting.
when join_cache_level < 5 and/or
optimizer switch join_cache_bka=off.
NO_BKA(t1,t2,..): disables BKA/BKAH join buffers, which could have been
chosen for the specified tables otherwise. However,
does not prevent employing of BNL/BNLH buffers.
@ -15710,22 +15716,19 @@ uint check_join_cache_usage(JOIN_TAB *tab,
!(join->allowed_join_cache_types & JOIN_CACHE_INCREMENTAL_BIT);
bool no_hashed_cache=
!(join->allowed_join_cache_types & JOIN_CACHE_HASHED_BIT);
bool no_bnl_cache= !hint_table_state_or_fallback(join->thd,
tab->tab_list->table, BNL_HINT_ENUM, true);
bool no_bka_cache= !hint_table_state_or_fallback(join->thd,
tab->tab_list->table, BKA_HINT_ENUM,
join->allowed_join_cache_types & JOIN_CACHE_BKA_BIT);
bool hint_forces_bka= hint_table_state_or_fallback(join->thd,
tab->tab_list->table,
BKA_HINT_ENUM, false);
bool no_bnl_cache= !hint_table_state(join->thd, tab->tab_list->table,
BNL_HINT_ENUM, true);
bool no_bka_cache= !hint_table_state(join->thd, tab->tab_list->table,
BKA_HINT_ENUM, join->allowed_join_cache_types & JOIN_CACHE_BKA_BIT);
bool hint_forces_bka= hint_table_state(join->thd, tab->tab_list->table,
BKA_HINT_ENUM, false);
join->return_tab= 0;
if (tab->no_forced_join_cache || (no_bnl_cache && no_bka_cache))
goto no_join_cache;
if (cache_level < 4 && hint_table_state_or_fallback(join->thd,
tab->tab_list->table,
BNL_HINT_ENUM, false))
if (cache_level < 4 && hint_table_state(join->thd, tab->tab_list->table,
BNL_HINT_ENUM, false))
{
cache_level= 4; // BNL() hint present, raise join_cache_level to BNLH
}
@ -32445,6 +32448,13 @@ void JOIN::set_allowed_join_cache_types()
max_allowed_join_cache_level= thd->variables.join_cache_level;
}
bool JOIN::is_allowed_hash_join_access(const TABLE *table)
{
return allowed_join_cache_types & JOIN_CACHE_HASHED_BIT &&
(max_allowed_join_cache_level > JOIN_CACHE_HASHED_BIT ||
hint_table_state(thd, table, BNL_HINT_ENUM, false) ||
hint_table_state(thd, table, BKA_HINT_ENUM, false));
}
/**
Save a query execution plan so that the caller can revert to it if needed,

6
sql/sql_select.h
View File

@ -1885,11 +1885,7 @@ public:
ulonglong curr_space,
ulonglong needed_space);
void set_allowed_join_cache_types();
bool is_allowed_hash_join_access()
{
return MY_TEST(allowed_join_cache_types & JOIN_CACHE_HASHED_BIT) &&
max_allowed_join_cache_level > JOIN_CACHE_HASHED_BIT;
}
bool is_allowed_hash_join_access(const TABLE *table);
/*
Check if we need to create a temporary table.
This has to be done if all tables are not already read (const tables)

Write Preview
Loading…
Cancel
Save