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From: Tom Lane <[email protected]>
To: David Rowley <[email protected]>
Cc: Chao Li <[email protected]>
Cc: Peter Eisentraut <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: Postgres hackers <[email protected]>
Subject: Re: Fix tuple deformation with virtual generated NOT NULL columns
Date: Wed, 17 Jun 2026 18:45:49 -0400
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
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	<[email protected]>

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

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