On Sat, Nov 14, 2020 at 2:04 PM Andy Fan <zhihui.fan1...@gmail.com> wrote: > > Hi: > > Take the following example: > > insert into cte1 select i, i from generate_series(1, 1000000)i; > create index on cte1(a); > > explain > with cte1 as (select * from cte1) > select * from c where a = 1; > > It needs to do seq scan on the above format, however it is pretty > quick if we change the query to > select * from (select * from cte1) c where a = 1; > > I know how we treat cte and subqueries differently currently, > I just don't know why we can't treat cte as a subquery, so lots of > subquery related technology can apply to it. Do we have any > discussion about this?
See https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=608b167f9f9c4553c35bb1ec0eab9ddae643989b
