1berry/MariaDB-server
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Some code optimisations related to EXPLAIN of derived tables and the

Browse Source 
resulting code cleanup in our main loop.
This commit is contained in:
unknown 2002-11-09 15:40:46 +02:00
parent 826aa607ff
commit f980950bb3
6 changed files with 37 additions and 90 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
mysql-test/r/subselect.result
View File

@ -71,8 +71,8 @@ select (select t3.a from t3 where a<8 order by 1 desc limit 1), a from
explain select (select t3.a from t3 where a<8 order by 1 desc limit 1), a from
(select * from t2 where a>1) as tt;
id select_type table type possible_keys key key_len ref rows Extra
3 DERIVED t2 ALL NULL NULL NULL NULL 2 where used
1 PRIMARY <derived3> system NULL NULL NULL NULL 1
3 DERIVED t2 ALL NULL NULL NULL NULL 2 where used
2 SUBSELECT t3 ALL NULL NULL NULL NULL 3 where used; Using filesort
select * from t1 where t1.a=(select t2.a from t2 where t2.b=(select max(a) from t3) order by 1 desc limit 1);
a

3
sql/mysql_priv.h
View File

@ -399,8 +399,7 @@ int mysql_explain_union(THD *thd, SELECT_LEX_UNIT *unit,
int mysql_explain_select(THD *thd, SELECT_LEX *sl, char const *type,
select_result *result);
int mysql_union(THD *thd, LEX *lex,select_result *result);
int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *s, TABLE_LIST *t,
bool tables_is_opened);
int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *s, TABLE_LIST *t);
Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
Item_result_field ***copy_func, Field **from_field,
bool group,bool modify_item);

10
sql/sql_derived.cc
View File

@ -28,8 +28,7 @@
static const char *any_db="*any*"; // Special symbol for check_access
int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t,
bool tables_is_opened)
int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t)
{
/*
TODO: make derived tables with union inside (now only 1 SELECT may be
@ -58,7 +57,7 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t,
if (cursor->derived)
{
res= mysql_derived(thd, lex, (SELECT_LEX_UNIT *)cursor->derived,
cursor, 0);
cursor);
if (res) DBUG_RETURN(res);
}
}
@ -68,7 +67,7 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t,
while ((item= it++))
item_list.push_back(item);
if (tables_is_opened || !(res=open_and_lock_tables(thd,tables)))
if (!(res=open_and_lock_tables(thd,tables)))
{
if (setup_fields(thd,tables,item_list,0,0,1))
{
@ -112,7 +111,8 @@ int mysql_derived(THD *thd, LEX *lex, SELECT_LEX_UNIT *unit, TABLE_LIST *t,
t->real_name=table->real_name;
t->table=table;
table->derived_select_number= sl->select_number;
sl->exclude();
if (!lex->describe)
sl->exclude();
t->db= (tables && tables->db && tables->db[0]) ? t->db : thd->db;
t->derived=(SELECT_LEX *)0; // just in case ...
}

1
sql/sql_lex.cc
View File

@ -959,6 +959,7 @@ void st_select_lex::init_query()
table_list.next= (byte**) &table_list.first;
item_list.empty();
join= 0;
olap= UNSPECIFIED_OLAP_TYPE;
}
void st_select_lex::init_select()

107
sql/sql_parse.cc
View File

@ -1328,74 +1328,24 @@ mysql_execute_command(THD *thd)
#endif
}
select_result *explain_result= 0;
/*
TODO: make derived tables processing 'inside' SELECT processing.
TODO: solve problem with depended derived tables in subselects
*/
if (lex->sql_command == SQLCOM_SELECT &&
lex->describe && lex->derived_tables)
{
if (!(explain_result= new select_send()))
{
send_error(thd, ER_OUT_OF_RESOURCES);
DBUG_VOID_RETURN;
}
//check rights
for (cursor= tables;
cursor;
cursor= cursor->next)
if (cursor->derived)
{
TABLE_LIST *tables=
(TABLE_LIST *)((SELECT_LEX_UNIT *)
cursor->derived)->first_select()->table_list.first;
int res;
if (tables)
res= check_table_access(thd,SELECT_ACL, tables);
else
res= check_access(thd, SELECT_ACL, any_db);
if (res)
DBUG_VOID_RETURN;
}
thd->send_explain_fields(explain_result);
// EXPLAIN derived tables
for (cursor= tables;
cursor;
cursor= cursor->next)
if (cursor->derived)
{
SELECT_LEX *select_lex= ((SELECT_LEX_UNIT *)
cursor->derived)->first_select();
if (!open_and_lock_tables(thd,
(TABLE_LIST*) select_lex->table_list.first))
{
mysql_explain_select(thd, select_lex,
"DERIVED", explain_result);
// execute derived table SELECT to provide table for other SELECTs
if (mysql_derived(thd, lex, (SELECT_LEX_UNIT *)cursor->derived,
cursor, 1))
DBUG_VOID_RETURN;
}
else
DBUG_VOID_RETURN;
}
}
else if (lex->derived_tables)
if (lex->derived_tables)
{
for (TABLE_LIST *cursor= tables;
cursor;
cursor= cursor->next)
if (cursor->derived && (res=mysql_derived(thd, lex,
(SELECT_LEX_UNIT *)cursor->derived,
cursor, 0)))
cursor)))
{
if (res < 0)
send_error(thd,thd->killed ? ER_SERVER_SHUTDOWN : 0);
DBUG_VOID_RETURN;
}
}
}
if ((lex->select_lex.next_select_in_list() &&
lex->unit.create_total_list(thd, lex, &tables)) ||
(table_rules_on && tables && thd->slave_thread &&
@ -1435,19 +1385,18 @@ mysql_execute_command(THD *thd)
{
if (lex->describe)
{
if (!explain_result)
if (!(explain_result= new select_send()))
{
send_error(thd, ER_OUT_OF_RESOURCES);
DBUG_VOID_RETURN;
}
else
thd->send_explain_fields(explain_result);
if (!(result= new select_send()))
{
send_error(thd, ER_OUT_OF_RESOURCES);
DBUG_VOID_RETURN;
}
else
thd->send_explain_fields(result);
fix_tables_pointers(select_lex);
res= mysql_explain_union(thd, &thd->lex.unit, explain_result);
res= mysql_explain_union(thd, &thd->lex.unit, result);
MYSQL_LOCK *save_lock= thd->lock;
thd->lock= (MYSQL_LOCK *)0;
explain_result->send_eof();
result->send_eof();
thd->lock= save_lock;
}
else
@ -2901,26 +2850,24 @@ void
mysql_init_query(THD *thd)
{
DBUG_ENTER("mysql_init_query");
thd->lex.unit.init_query();
thd->lex.unit.init_select();
thd->lex.select_lex.init_query();
thd->lex.unit.slave= &thd->lex.select_lex;
thd->lex.unit.global_parameters= &thd->lex.select_lex; //Global limit & order
thd->lex.select_lex.master= &thd->lex.unit;
thd->lex.select_lex.prev= &thd->lex.unit.slave;
thd->select_number= thd->lex.select_lex.select_number= 1;
thd->lex.value_list.empty();
LEX *lex=&thd->lex;
lex->unit.init_query();
lex->unit.init_select();
lex->select_lex.init_query();
lex->value_list.empty();
lex->param_list.empty();
lex->unit.global_parameters= lex->unit.slave= lex->current_select= &lex->select_lex;
lex->select_lex.master= &lex->unit;
lex->select_lex.prev= &lex->unit.slave;
lex->olap=lex->describe=0;
lex->derived_tables= false;
thd->select_number= lex->select_lex.select_number= 1;
thd->free_list= 0;
thd->lex.current_select= &thd->lex.select_lex;
thd->lex.olap=thd->lex.describe=0;
thd->lex.select_lex.olap= UNSPECIFIED_OLAP_TYPE;
thd->fatal_error= 0; // Safety
thd->total_warn_count=0; // Warnings for this query
thd->last_insert_id_used= thd->query_start_used= thd->insert_id_used=0;
thd->sent_row_count= thd->examined_row_count= 0;
thd->rand_used=0;
thd->fatal_error= thd->rand_used=0;
thd->safe_to_cache_query= 1;
thd->lex.param_list.empty();
DBUG_VOID_RETURN;
}
@ -2932,7 +2879,6 @@ mysql_init_select(LEX *lex)
select_lex->init_select();
select_lex->master_unit()->select_limit= select_lex->select_limit=
lex->thd->variables.select_limit;
select_lex->olap= UNSPECIFIED_OLAP_TYPE;
lex->exchange= 0;
lex->result= 0;
lex->proc_list.first= 0;
@ -3016,14 +2962,13 @@ mysql_parse(THD *thd, char *inBuf, uint length)
mysql_init_query(thd);
thd->query_length = length;
thd->lex.derived_tables= false;
if (query_cache_send_result_to_client(thd, inBuf, length) <= 0)
{
LEX *lex=lex_start(thd, (uchar*) inBuf, length);
if (!yyparse() && ! thd->fatal_error)
{
if (mqh_used && thd->user_connect &&
check_mqh(thd, thd->lex.sql_command))
check_mqh(thd, lex->sql_command))
{
thd->net.error = 0;
}

4
sql/sql_select.cc
View File

@ -7458,8 +7458,10 @@ int mysql_explain_union(THD *thd, SELECT_LEX_UNIT *unit, select_result *result)
((sl->next_select_in_list())?"PRIMARY":
"SIMPLE"):
((sl == first)?
((sl->linkage == DERIVED_TABLE_TYPE) ?
"DERIVED":
((sl->dependent)?"DEPENDENT SUBSELECT":
"SUBSELECT"):
"SUBSELECT")):
((sl->dependent)?"DEPENDENT UNION":
"UNION"))),
result);