Re: [POC] Allow flattening of subquery with a link to upper query - Mailing list pgsql-hackers

From Zhihong Yu
Subject Re: [POC] Allow flattening of subquery with a link to upper query
Date
Msg-id CALNJ-vQ_1mB4BrObnP7V4VQxa48hPs9qw36A4bteve3VaH04Vw@mail.gmail.com
Whole thread Raw
In response to Re: [POC] Allow flattening of subquery with a link to upper query  (Andrey Lepikhov <a.lepikhov@postgrespro.ru>)
List pgsql-hackers


On Wed, Oct 5, 2022 at 4:38 AM Andrey Lepikhov <a.lepikhov@postgrespro.ru> wrote:
On 5/10/2022 02:45, Zhihong Yu wrote:
> Hi,
> For contain_placeholders():
>
> +   if (IsA(node, Query))
> +       return query_tree_walker((Query *) node, contain_placeholders,
> context, 0);
> +   else if (IsA(node, PlaceHolderVar))
Fixed
>
> The `else` is not needed.
>
> For correlated_t struct, it would be better if the fields have comments.
Ok, I've added some comments.
>
> +                    * (for grouping, as an example). So, revert its
> status to
> +                    * a full valued entry.
>
> full valued -> fully valued
Fixed

--
regards,
Andrey Lepikhov
Postgres Professional
Hi,

+   List   *pulling_quals; /* List of expressions contained pulled expressions */

contained -> containing

+           /* Does the var already exists in the target list? */

 exists -> exist

+       {"optimize_correlated_subqueries", PGC_USERSET, QUERY_TUNING_METHOD,

Is it possible that in the future there would be other optimization for correlated subqueries ?
If so, either rename the guc or, make the guc a string which represents an enum.

Cheers

pgsql-hackers by date:

Previous
From: Tom Lane
Date:
Subject: Re: Can we avoid chdir'ing in resolve_symlinks() ?
Next
From: Tom Lane
Date:
Subject: Re: shadow variables - pg15 edition