Replaces the auto_join scheme which is pretty fast but doesn't quite
work (it's *completely* broken for read_group) by a subquery which is
slower but has the same semantics as the ORM version.
Ideally we'd use `EXISTS (select 1 from ...)` but that has no support
inside the SQL compiler right now, so use `id in (select inverse_field
from ...)`.
Here are some measures of a `read_group` on a simple object with lines
filtered on line values, similar to
read_group([('order_line.product_uom', '=', xxx)],
fields=['total_amount'], groupby=['user_id'])
+-------+-------+-------+--------+
| | ORM | join |subquery|
+-------+-------+-------+--------+
| large | 160 | 10 | 20 |
+-------+-------+-------+--------+
| many | 36000 | 50 | 180 |
+-------+-------+-------+--------+
* values of data fields (filtering, grouping and aggregating) randomly
picked between 10 different values
* "large" is 1000 objects with 1000~15000 lines each
* "many" is 1000000 objects with 1~40 lines each
closesodoo/odoo#48494
Signed-off-by: Raphael Collet (rco) <rco@openerp.com>
Xavier Morel
7a7b5b5d9d