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MDEV-7811: EXPLAIN/ANALYZE FORMAT=JSON should show subquery cache

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This commit is contained in:
Oleksandr Byelkin 2015-03-25 18:27:10 +01:00 committed by Sergei Petrunia
parent 498a264d19
commit c6aee27b73
11 changed files with 401 additions and 9 deletions
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234
mysql-test/r/subselect_cache.result
View File

@ -39,6 +39,240 @@ Handler_read_prev 0
Handler_read_rnd 0
Handler_read_rnd_deleted 0
Handler_read_rnd_next 31
analyze format=json
select a, (select d from t2 where b=c) from t1;
ANALYZE
{
"query_block": {
"select_id": 1,
"r_loops": 1,
"r_total_time_ms": "REPLACED",
"table": {
"table_name": "t1",
"access_type": "ALL",
"r_loops": 1,
"rows": 10,
"r_rows": 10,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100
},
"subqueries": [
{
"query_block": {
"select_id": 2,
"r_loops": 4,
"r_total_time_ms": "REPLACED",
"expression_cache": {
"state": "ENABLED",
"r_hit": 6,
"r_miss": 4,
"r_loops": 10,
"r_hit_ratio": 60
},
"table": {
"table_name": "t2",
"access_type": "ALL",
"r_loops": 4,
"rows": 4,
"r_rows": 4,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 18.75,
"attached_condition": "(t1.b = t2.c)"
}
}
}
]
}
}
analyze format=json
select a, (select d from t2 where b=c), (select d from t2 where b=c union select 1 order by 1 limit 1) from t1;
ANALYZE
{
"query_block": {
"select_id": 1,
"r_loops": 1,
"r_total_time_ms": "REPLACED",
"table": {
"table_name": "t1",
"access_type": "ALL",
"r_loops": 1,
"rows": 10,
"r_rows": 10,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100
},
"subqueries": [
{
"query_block": {
"union_result": {
"table_name": "<union3,4>",
"access_type": "ALL",
"r_loops": 4,
"r_rows": 1,
"expression_cache": {
"state": "ENABLED",
"r_hit": 6,
"r_miss": 4,
"r_loops": 10,
"r_hit_ratio": 60
},
"query_specifications": [
{
"query_block": {
"select_id": 3,
"r_loops": 4,
"r_total_time_ms": "REPLACED",
"table": {
"table_name": "t2",
"access_type": "ALL",
"r_loops": 4,
"rows": 4,
"r_rows": 4,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 18.75,
"attached_condition": "(t1.b = t2.c)"
}
}
},
{
"query_block": {
"select_id": 4,
"table": {
"message": "No tables used"
}
}
}
]
}
}
},
{
"query_block": {
"select_id": 2,
"r_loops": 4,
"r_total_time_ms": "REPLACED",
"expression_cache": {
"state": "ENABLED",
"r_hit": 6,
"r_miss": 4,
"r_loops": 10,
"r_hit_ratio": 60
},
"table": {
"table_name": "t2",
"access_type": "ALL",
"r_loops": 4,
"rows": 4,
"r_rows": 4,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 18.75,
"attached_condition": "(t1.b = t2.c)"
}
}
}
]
}
}
explain format=json
select a, (select d from t2 where b=c) from t1;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100
},
"subqueries": [
{
"query_block": {
"select_id": 2,
"expression_cache": {
"state": "UNINITIALYZED"
},
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 4,
"filtered": 100,
"attached_condition": "(t1.b = t2.c)"
}
}
}
]
}
}
explain format=json
select a, (select d from t2 where b=c), (select d from t2 where b=c union select 1 order by 1 limit 1) from t1;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100
},
"subqueries": [
{
"query_block": {
"union_result": {
"table_name": "<union3,4>",
"access_type": "ALL",
"expression_cache": {
"state": "UNINITIALYZED"
},
"query_specifications": [
{
"query_block": {
"select_id": 3,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 4,
"filtered": 100,
"attached_condition": "(t1.b = t2.c)"
}
}
},
{
"query_block": {
"select_id": 4,
"table": {
"message": "No tables used"
}
}
}
]
}
}
},
{
"query_block": {
"select_id": 2,
"expression_cache": {
"state": "UNINITIALYZED"
},
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 4,
"filtered": 100,
"attached_condition": "(t1.b = t2.c)"
}
}
}
]
}
}
set optimizer_switch='subquery_cache=off';
flush status;
select a, (select d from t2 where b=c) from t1;

10
mysql-test/t/subselect_cache.test
View File

@ -24,6 +24,16 @@ select a, (select d from t2 where b=c) from t1;
show status like "subquery_cache%";
show status like '%Handler_read%';
--replace_regex /"r_total_time_ms": [0-9]*[.]?[0-9]*/"r_total_time_ms": "REPLACED"/
analyze format=json
select a, (select d from t2 where b=c) from t1;
--replace_regex /"r_total_time_ms": [0-9]*[.]?[0-9]*/"r_total_time_ms": "REPLACED"/
analyze format=json
select a, (select d from t2 where b=c), (select d from t2 where b=c union select 1 order by 1 limit 1) from t1;
explain format=json
select a, (select d from t2 where b=c) from t1;
explain format=json
select a, (select d from t2 where b=c), (select d from t2 where b=c union select 1 order by 1 limit 1) from t1;
set optimizer_switch='subquery_cache=off';
flush status;

13
sql/item.cc
View File

@ -7554,6 +7554,19 @@ bool Item_cache_wrapper::set_cache(THD *thd)
DBUG_RETURN(expr_cache == NULL);
}
Expression_cache_stat* Item_cache_wrapper::set_stat(MEM_ROOT *mem_root)
{
if (expr_cache)
{
Expression_cache_stat* stat=
new(mem_root) Expression_cache_stat(expr_cache);
if (stat)
((Expression_cache_tmptable *)expr_cache)->set_stat(stat);
return stat;
}
return NULL;
}
/**
Check if the current values of the parameters are in the expression cache

2
sql/item.h
View File

@ -3804,6 +3804,7 @@ public:
class Item_cache;
class Expression_cache;
class Expression_cache_stat;
/**
The objects of this class can store its values in an expression cache.
@ -3838,6 +3839,7 @@ public:
enum Type real_type() const { return orig_item->type(); }
bool set_cache(THD *thd);
Expression_cache_stat* set_stat(MEM_ROOT *mem_root);
bool fix_fields(THD *thd, Item **it);
void cleanup();

19
sql/item_subselect.cc
View File

@ -1201,7 +1201,10 @@ Item* Item_singlerow_subselect::expr_cache_insert_transformer(uchar *thd_arg)
if (expr_cache_is_needed(thd) &&
(expr_cache= set_expr_cache(thd)))
{
set_expr_cache_stat(thd);
DBUG_RETURN(expr_cache);
}
DBUG_RETURN(this);
}
@ -1497,7 +1500,10 @@ Item* Item_exists_subselect::expr_cache_insert_transformer(uchar *thd_arg)
if (substype() == EXISTS_SUBS && expr_cache_is_needed(thd) &&
(expr_cache= set_expr_cache(thd)))
{
set_expr_cache_stat(thd);
DBUG_RETURN(expr_cache);
}
DBUG_RETURN(this);
}
@ -6556,3 +6562,16 @@ void subselect_table_scan_engine::cleanup()
{
}
void Item_subselect::set_expr_cache_stat(THD *thd)
{
if(!expr_cache)
return;
Explain_query *qw= thd->lex->explain;
DBUG_ASSERT(qw);
Explain_node *node= qw->get_node(unit->first_select()->select_number);
if (!node)
return;
DBUG_ASSERT(expr_cache->type() == Item::EXPR_CACHE_ITEM);
node->cache_stat= ((Item_cache_wrapper *)expr_cache)->set_stat(qw->mem_root);
}

5
sql/item_subselect.h
View File

@ -244,7 +244,10 @@ public:
bool limit_index_condition_pushdown_processor(uchar *opt_arg)
{
return TRUE;
}
}
void set_expr_cache_stat(THD *thd);
friend class select_result_interceptor;
friend class Item_in_optimizer;

30
sql/sql_explain.cc
View File

@ -23,6 +23,7 @@
#include "sql_select.h"
#include "my_json_writer.h"
#include "opt_range.h"
#include "sql_expression_cache.h"
const char * STR_DELETING_ALL_ROWS= "Deleting all rows";
const char * STR_IMPOSSIBLE_WHERE= "Impossible WHERE";
@ -543,6 +544,7 @@ void Explain_union::print_explain_json(Explain_query *query,
writer->add_null();
}
print_explain_json_cache(writer, is_analyze);
writer->add_member("query_specifications").start_array();
for (int i= 0; i < (int) union_members.elements(); i++)
@ -640,6 +642,30 @@ void Explain_node::print_explain_json_for_children(Explain_query *query,
}
void Explain_node::print_explain_json_cache(Json_writer *writer,
bool is_analyze)
{
if (cache_stat)
{
cache_stat->flush_stat();
writer->add_member("expression_cache").start_object();
writer->add_member("state").
add_str(Expression_cache_stat::state_str[cache_stat->state]);
if (is_analyze)
{
writer->add_member("r_hit").add_ll(cache_stat->hit);
writer->add_member("r_miss").add_ll(cache_stat->miss);
writer->add_member("r_loops").add_ll(cache_stat->hit +
cache_stat->miss);
writer->add_member("r_hit_ratio").add_ll(((double)cache_stat->hit)/
((double)(cache_stat->hit +
cache_stat->miss)) * 100.0);
}
writer->end_object();
}
}
void Explain_select::replace_table(uint idx, Explain_table_access *new_tab)
{
delete join_tabs[idx];
@ -757,17 +783,19 @@ void Explain_select::print_explain_json(Explain_query *query,
{
writer->add_member("query_block").start_object();
writer->add_member("select_id").add_ll(select_id);
if (is_analyze && time_tracker.get_loops())
{
writer->add_member("r_loops").add_ll(time_tracker.get_loops());
writer->add_member("r_total_time_ms").add_double(time_tracker.get_time_ms());
}
if (exec_const_cond)
{
writer->add_member("const_condition");
write_item(writer, exec_const_cond);
}
print_explain_json_cache(writer, is_analyze);
Filesort_tracker *first_table_sort= NULL;
bool first_table_sort_used= false;

16
sql/sql_explain.h
View File

@ -84,9 +84,10 @@ class Explain_query;
class Explain_node : public Sql_alloc
{
public:
Explain_node(MEM_ROOT *root) :
connection_type(EXPLAIN_NODE_OTHER),
children(root)
Explain_node(MEM_ROOT *root) :
cache_stat(NULL),
connection_type(EXPLAIN_NODE_OTHER),
children(root)
{}
/* A type specifying what kind of node this is */
enum explain_node_type
@ -106,10 +107,14 @@ public:
EXPLAIN_NODE_NON_MERGED_SJ /* aka JTBM semi-join */
};
virtual enum explain_node_type get_type()= 0;
virtual int get_select_id()= 0;
/**
expression cache statistics
*/
Expression_cache_stat* cache_stat;
/*
How this node is connected to its parent.
(NOTE: EXPLAIN_NODE_NON_MERGED_SJ is set very late currently)
@ -135,6 +140,7 @@ public:
uint8 explain_flags, bool is_analyze);
void print_explain_json_for_children(Explain_query *query,
Json_writer *writer, bool is_analyze);
void print_explain_json_cache(Json_writer *writer, bool is_analyze);
virtual ~Explain_node(){}
};
@ -221,7 +227,7 @@ public:
members have no info
*/
const char *message;
/* Expensive constant condition */
Item *exec_const_cond;

15
sql/sql_expression_cache.cc
View File

@ -43,7 +43,7 @@ ulong subquery_cache_miss, subquery_cache_hit;
Expression_cache_tmptable::Expression_cache_tmptable(THD *thd,
List<Item> &dependants,
Item *value)
:cache_table(NULL), table_thd(thd), items(dependants), val(value),
:cache_table(NULL), table_thd(thd), stat(NULL), items(dependants), val(value),
hit(0), miss(0), inited (0)
{
DBUG_ENTER("Expression_cache_tmptable::Expression_cache_tmptable");
@ -61,6 +61,9 @@ void Expression_cache_tmptable::disable_cache()
cache_table->file->ha_index_end();
free_tmp_table(table_thd, cache_table);
cache_table= NULL;
flush_stat();
if (stat)
stat->cache= NULL;
}
@ -164,6 +167,7 @@ void Expression_cache_tmptable::init()
goto error;
}
flush_stat();
DBUG_VOID_RETURN;
error:
@ -180,6 +184,11 @@ Expression_cache_tmptable::~Expression_cache_tmptable()
if (cache_table)
disable_cache();
else
{
flush_stat();
stat= NULL;
}
}
@ -323,3 +332,7 @@ void Expression_cache_tmptable::print(String *str, enum_query_type query_type)
}
str->append('>');
}
const char *Expression_cache_stat::state_str[3]=
{"UNINITIALYZED", "DISABLED", "ENABLED"};

48
sql/sql_expression_cache.h
View File

@ -19,6 +19,7 @@
#include "sql_select.h"
/**
Interface for expression cache
@ -62,6 +63,11 @@ public:
Initialize this cache
*/
virtual void init()= 0;
/**
Save this object's statistics into Expression_cache_stat object
*/
virtual void flush_stat()= 0;
};
struct st_table_ref;
@ -69,6 +75,30 @@ struct st_join_table;
class Item_field;
class Expression_cache_stat :public Sql_alloc
{
public:
enum expr_cache_state {UNINITED, STOPPED, OK};
Expression_cache_stat(Expression_cache *c) :
cache(c), hit(0), miss(0), state(UNINITED)
{}
Expression_cache *cache;
ulong hit, miss;
enum expr_cache_state state;
static const char* state_str[3];
void set(ulong h, ulong m, enum expr_cache_state s)
{hit= h; miss= m; state= s;}
void flush_stat()
{
if (cache)
cache->flush_stat();
}
};
/**
Implementation of expression cache over a temporary table
*/
@ -85,6 +115,20 @@ public:
bool is_inited() { return inited; };
void init();
void set_stat(Expression_cache_stat *st)
{
stat= st;
flush_stat();
}
virtual void flush_stat()
{
if (stat)
stat->set(hit, miss, (inited ? (cache_table ?
Expression_cache_stat::OK :
Expression_cache_stat::STOPPED) :
Expression_cache_stat::UNINITED));
}
private:
void disable_cache();
@ -94,6 +138,8 @@ private:
TABLE *cache_table;
/* Thread handle for the temporary table */
THD *table_thd;
/* EXPALIN/ANALYZE statistics */
Expression_cache_stat *stat;
/* TABLE_REF for index lookup */
struct st_table_ref ref;
/* Cached result */
@ -103,7 +149,7 @@ private:
/* Value Item example */
Item *val;
/* hit/miss counters */
uint hit, miss;
ulong hit, miss;
/* Set on if the object has been succesfully initialized with init() */
bool inited;
};

18
sql/sql_lex.cc
View File

@ -3505,6 +3505,8 @@ bool st_select_lex::optimize_unflattened_subqueries(bool const_only)
bool empty_union_result= true;
bool is_correlated_unit= false;
bool first= true;
bool union_plan_saved= false;
/*
If the subquery is a UNION, optimize all the subqueries in the UNION. If
there is no UNION, then the loop will execute once for the subquery.
@ -3512,6 +3514,17 @@ bool st_select_lex::optimize_unflattened_subqueries(bool const_only)
for (SELECT_LEX *sl= un->first_select(); sl; sl= sl->next_select())
{
JOIN *inner_join= sl->join;
if (first)
first= false;
else
{
if (!union_plan_saved)
{
union_plan_saved= true;
if (un->save_union_explain(un->thd->lex->explain))
return true; /* Failure */
}
}
if (!inner_join)
continue;
SELECT_LEX *save_select= un->thd->lex->current_select;
@ -4365,10 +4378,15 @@ void LEX::restore_set_statement_var()
int st_select_lex_unit::save_union_explain(Explain_query *output)
{
SELECT_LEX *first= first_select();
if (output->get_union(first->select_number))
return 0; /* Already added */
Explain_union *eu=
new (output->mem_root) Explain_union(output->mem_root,
thd->lex->analyze_stmt);
if (derived)
eu->connection_type= Explain_node::EXPLAIN_NODE_DERIVED;
/*