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(This has been previously discussed with Timour, I'm just filing the task now)
Currently, EXPLAIN shows subqueries like this:
create table ten(a int); insert into ten values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t1 (a int, b int) as select a as a, a as b from ten; mysql> explain select * from ten where a > (select max(b) from t1 where t1.b <= ten.a); +------+--------------------+-------+------+---------------+------+---------+------+------+----------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +------+--------------------+-------+------+---------------+------+---------+------+------+----------------------------+ | 1 | PRIMARY | ten | ALL | NULL | NULL | NULL | NULL | 10 | Using where; Subqueries: 2 | | 2 | DEPENDENT SUBQUERY | t1 | ALL | NULL | NULL | NULL | NULL | 10 | Using where | +------+--------------------+-------+------+---------------+------+---------+------+------+----------------------------+
This is not user-friendly, "Subqueries: 2" reads as if there were two
subqueries attached, while actually it is one subquery #2 that is attached.
Tentative new syntax:
Subquery #n Subquery #n1, #n2
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- is part of
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MDEV-83 Cost-based choice for the pushdown of subqueries to joined tables
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- Stalled
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