Re: optimizing large query with IN (...)

Hmm... from the 'performance' point of view, since the data comes from
a quite complex select statement, Isn't it better/quicker to have this
select replaced by a select into and creating a temporary database?



> The problem, as I understand it, is that 7.4 introduced massive
> improvements in handling moderately large in() clauses, as long as they
> can fit in sort_mem, and are provided by a subselect.
>
> So, creating a temp table with all the values in it and using in() on
> the  temp table may be a win:
>
> begin;
> create temp table t_ids(id int);
> insert into t_ids(id) values (123); <- repeat a few hundred times
> select * from maintable where id in (select id from t_ids);
> ...