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join_nested.test, join_nested.result:

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  Nested joins added.
This commit is contained in:
igor@rurik.mysql.com
2004-06-10 22:27:21 -07:00
parent f9e2c6cd27
commit 356cbe4fa2
14 changed files with 3148 additions and 239 deletions
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232
sql/sql_parse.cc
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@@ -4686,6 +4686,238 @@ TABLE_LIST *st_select_lex::add_table_to_list(THD *thd,
}
/*
Initialize a new table list for a nested join
SYNOPSIS
init_table_list()
thd current thread
DESCRIPTION
The function initializes a structure of the TABLE_LIST type
for a nested join. It sets up its nested join list as empty.
The created structure is added to the front of the current
join list in the st_select_lex object. Then the function
changes the current nest level for joins to refer to the newly
created empty list after having saved the info on the old level
in the initialized structure.
RETURN VALUE
0, if success
1, otherwise
*/
bool st_select_lex::init_nested_join(THD *thd)
{
TABLE_LIST *ptr;
NESTED_JOIN *nested_join;
DBUG_ENTER("init_nested_join");
if (!(ptr = (TABLE_LIST *) thd->calloc(sizeof(TABLE_LIST))) ||
!(nested_join= ptr->nested_join=
(NESTED_JOIN *) thd->calloc(sizeof(NESTED_JOIN))))
DBUG_RETURN(1);
join_list->push_front(ptr);
ptr->embedding= embedding;
ptr->join_list= join_list;
embedding= ptr;
join_list= &nested_join->join_list;
join_list->empty();
nested_join->used_tables= nested_join->not_null_tables= (table_map) 0;
DBUG_RETURN(0);
}
/*
End a nested join table list
SYNOPSIS
end_nested_join()
thd current thread
DESCRIPTION
The function returns to the previous join nest level.
If the current level contains only one member, the function
moves it one level up, eliminating the nest.
RETURN VALUE
Pointer to TABLE_LIST element added to the total table list, if success
0, otherwise
*/
TABLE_LIST *st_select_lex::end_nested_join(THD *thd)
{
TABLE_LIST *ptr;
DBUG_ENTER("end_nested_join");
ptr= embedding;
join_list= ptr->join_list;
embedding= ptr->embedding;
NESTED_JOIN *nested_join= ptr->nested_join;
if (nested_join->join_list.elements == 1)
{
TABLE_LIST *embedded= nested_join->join_list.head();
join_list->pop();
embedded->join_list= join_list;
embedded->embedding= embedding;
join_list->push_front(embedded);
ptr= embedded;
}
DBUG_RETURN(ptr);
}
/*
Nest last join operation
SYNOPSIS
nest_last_join()
thd current thread
DESCRIPTION
The function nest last join operation as if it was enclosed in braces.
RETURN VALUE
Pointer to TABLE_LIST element created for the new nested join, if success
0, otherwise
*/
TABLE_LIST *st_select_lex::nest_last_join(THD *thd)
{
TABLE_LIST *ptr;
NESTED_JOIN *nested_join;
DBUG_ENTER("nest_last_join");
if (!(ptr = (TABLE_LIST *) thd->calloc(sizeof(TABLE_LIST))) ||
!(nested_join= ptr->nested_join=
(NESTED_JOIN *) thd->calloc(sizeof(NESTED_JOIN))))
DBUG_RETURN(0);
ptr->embedding= embedding;
ptr->join_list= join_list;
List<TABLE_LIST> *embedded_list= &nested_join->join_list;
embedded_list->empty();
for (int i=0; i < 2; i++)
{
TABLE_LIST *table= join_list->pop();
table->join_list= embedded_list;
table->embedding= ptr;
embedded_list->push_back(table);
}
join_list->push_front(ptr);
nested_join->used_tables= nested_join->not_null_tables= (table_map) 0;
DBUG_RETURN(ptr);
}
/*
Save names for a join with using clase
SYNOPSIS
save_names_for_using_list
tab1 left table in join
tab2 right table in join
DESCRIPTION
The function saves the full names of the tables in st_select_lex
to be able to build later an on expression to replace the using clause.
RETURN VALUE
None
*/
void st_select_lex::save_names_for_using_list(TABLE_LIST *tab1,
TABLE_LIST *tab2)
{
while (tab1->nested_join)
{
tab1= tab1->nested_join->join_list.head();
}
db1= tab1->db;
table1= tab1->alias;
while (tab2->nested_join)
{
TABLE_LIST *next;
List_iterator_fast<TABLE_LIST> it(tab2->nested_join->join_list);
tab2= it++;
while ((next= it++))
tab2= next;
}
db2= tab2->db;
table2= tab2->alias;
}
/*
Add a table to the current join list
SYNOPSIS
add_joined_table()
table the table to add
DESCRIPTION
The function puts a table in front of the current join list
of st_select_lex object.
Thus, joined tables are put into this list in the reverse order
(the most outer join operation follows first).
RETURN VALUE
None
*/
void st_select_lex::add_joined_table(TABLE_LIST *table)
{
DBUG_ENTER("add_joined_table");
join_list->push_front(table);
table->join_list= join_list;
table->embedding= embedding;
DBUG_VOID_RETURN;
}
/*
Convert a right join into equivalent left join
SYNOPSIS
convert_right_join()
thd current thread
DESCRIPTION
The function takes the current join list t[0],t[1] ... and
effectively converts it into the list t[1],t[0] ...
Although the outer_join flag for the new nested table contains
JOIN_TYPE_RIGHT, it will be handled as the inner table of a left join
operation.
EXAMPLES
SELECT * FROM t1 RIGHT JOIN t2 ON on_expr =>
SELECT * FROM t2 LEFT JOIN t1 ON on_expr
SELECT * FROM t1,t2 RIGHT JOIN t3 ON on_expr =>
SELECT * FROM t1,t3 LEFT JOIN t2 ON on_expr
SELECT * FROM t1,t2 RIGHT JOIN (t3,t4) ON on_expr =>
SELECT * FROM t1,(t3,t4) LEFT JOIN t2 ON on_expr
SELECT * FROM t1 LEFT JOIN t2 ON on_expr1 RIGHT JOIN t3 ON on_expr2 =>
SELECT * FROM t3 LEFT JOIN (t1 LEFT JOIN t2 ON on_expr2) ON on_expr1
RETURN
Pointer to the table representing the inner table, if success
0, otherwise
*/
TABLE_LIST *st_select_lex::convert_right_join()
{
TABLE_LIST *tab2= join_list->pop();
TABLE_LIST *tab1= join_list->pop();
DBUG_ENTER("convert_right_join");
join_list->push_front(tab2);
join_list->push_front(tab1);
tab1->outer_join|= JOIN_TYPE_RIGHT;
DBUG_RETURN(tab1);
}
/*
Set lock for all tables in current select level