public inbox for [email protected]
help / color / mirror / Atom feedFrom: Dean Rasheed <[email protected]>
To: Yugo Nagata <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: [email protected]
Subject: Re: Allow to collect statistics on virtual generated columns
Date: Thu, 26 Mar 2026 17:25:23 +0000
Message-ID: <CAEZATCXkZwJ_6FCM7RMKFiNC4ui+CLmL-=Y9AiYmDpnPS+ftWw@mail.gmail.com> (raw)
In-Reply-To: <CAEZATCWkQhG0fwz5Z34vn=LcKdCb3DGfomPPwcXL_qtKfEt5+w@mail.gmail.com>
References: <[email protected]>
<kp43uuykq64fyqxnlihq2rzntarextvzibuzturajfucl6bayo@6fcnflboemtt>
<[email protected]>
<[email protected]>
<[email protected]>
<[email protected]>
<[email protected]>
<[email protected]>
<CAEZATCV6=q0-5HFBMg4jFS-j1ZCwANhp1sLXBQZYsK2ZLwq0AQ@mail.gmail.com>
<[email protected]>
<CAEZATCUR5B=6M7H2bwRU0_6FrbSE8yHe_+9bTbRUdU=jE33yog@mail.gmail.com>
<[email protected]>
<[email protected]>
<CAEZATCWkQhG0fwz5Z34vn=LcKdCb3DGfomPPwcXL_qtKfEt5+w@mail.gmail.com>
On Thu, 26 Mar 2026 at 16:00, Dean Rasheed <[email protected]> wrote:
>
> On Thu, 26 Mar 2026 at 15:09, Yugo Nagata <[email protected]> wrote:
> >
> > I've attached an updated patch including the documentation and tests.
Looking at get_relation_statistics(), I think that you need to call
expand_generated_columns_in_expr() *before* ChangeVarNodes() so that
Vars in the expanded expression end up with the correct varno.
This obviously affects queries with more than one table in the FROM
clause, e.g.:
drop table if exists foo;
create table foo (a int, b int generated always as (a*2) virtual);
insert into foo select x from generate_series(1,10) x;
insert into foo select 100 from generate_series(1,500);
create statistics s on b from foo;
analyse foo;
explain select * from foo f1, foo f2 where f1.b = 200 and f2.b = 200;
QUERY PLAN
-------------------------------------------------------------------
Nested Loop (cost=0.00..47.56 rows=1500 width=16)
-> Seq Scan on foo f1 (cost=0.00..10.65 rows=500 width=4)
Filter: ((a * 2) = 200)
-> Materialize (cost=0.00..10.66 rows=3 width=4)
-> Seq Scan on foo f2 (cost=0.00..10.65 rows=3 width=4)
Filter: ((a * 2) = 200)
(6 rows)
Regards,
Dean
view thread (21+ messages) latest in thread
reply
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: [email protected]
Cc: [email protected], [email protected], [email protected]
Subject: Re: Allow to collect statistics on virtual generated columns
In-Reply-To: <CAEZATCXkZwJ_6FCM7RMKFiNC4ui+CLmL-=Y9AiYmDpnPS+ftWw@mail.gmail.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox