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Re: Bug: Rule actions see wrong values for generated columns (NEW.gen reads OLD value)

Dean Rasheed <dean.a.rasheed@gmail.com>

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From: Dean Rasheed <dean.a.rasheed@gmail.com>
To: Richard Guo <guofenglinux@gmail.com>
Cc: Chao Li <li.evan.chao@gmail.com>, SATYANARAYANA NARLAPURAM <satyanarlapuram@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Peter Eisentraut <peter@eisentraut.org>
Date: 2026-04-20T08:42:31Z
Lists: pgsql-hackers 
On Mon, 20 Apr 2026 at 08:29, Richard Guo <guofenglinux@gmail.com> wrote:
>
> I noticed a couple of issues after a further look.
>
> 1. The ReplaceVarsFromTargetList call on "gen_cols" fails to handle
> hasSubLinks.  This can cause error if targetList contains SubLinks:
>
> update t set a = (select max(a) from t);
> ERROR:  replace_rte_variables inserted a SubLink, but has noplace to record it
>

Doh, yes, careless copy-and-pasting. The updates look good.

> 2. The same bug fixed in this patch also exists in rule quals:
>
> I think we should apply the same fix to CopyAndAddInvertedQual.
>

Agreed.

> Attached v3 fixes them.
>

LGTM.

Regards,
Dean

Commits

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  1. Fix incorrect NEW references to generated columns in rule rewriting