Horton

Re: Fix tuple deformation with virtual generated NOT NULL columns

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Chao Li <li.evan.chao@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, Andres Freund <andres@anarazel.de>, Postgres hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-06-17T22:45:49Z
Lists: pgsql-hackers 
I wrote:
> Speculating wildly, I'm wondering about an uninitialized variable that
> happens to usually have the right value.

Nope: valgrind finds nothing, and neither does debug_discard_caches.
What does reproduce it, with seeming 100% reliability, is

set jit = 1;
set jit_above_cost = 0;
set jit_optimize_above_cost = 1000;
CREATE TABLE gtest21c (a int NOT NULL, b int GENERATED ALWAYS AS (a * 2) VIRTUAL NOT NULL, c int NOT NULL);
INSERT INTO gtest21c (a, c) VALUES (10, 42);
table gtest21c;

I conclude that something in the JIT code for tuple formation
is unaware of virtual generated columns.

			regards, tom lane

Commits

  1. Update JIT tuple deforming code for virtual generated columns

  2. Add tuple deformation test for virtual generated columns

  3. Fix tuple deforming with virtual generated columns