BUG #19651: to_date()/to_timestamp() silently accept out-of-range values for SSSSS, RM, IW and ID format fields

From: PG Bug reporting form <noreply(at)postgresql(dot)org>
To: pgsql-bugs(at)lists(dot)postgresql(dot)org
Cc: 303677365(at)qq(dot)com
Subject: BUG #19651: to_date()/to_timestamp() silently accept out-of-range values for SSSSS, RM, IW and ID format fields
Date: 2026-09-03 06:46:30
Message-ID: 19651-fdc8457e83a39ba1@postgresql.org
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The following bug has been logged on the website:

Bug reference: 19651
Logged by: chunling qin
Email address: 303677365(at)qq(dot)com
PostgreSQL version: 18.6
Operating system: x86_64
Description:

Four to_date()/to_timestamp() format fields whose documented value ranges
are narrow accept out-of-range input silently and produce a wrong date,
while sister fields in the same domain raise errors for the same kind of
input:

1. SSSSS (seconds since midnight, documented 0-86399) — negative value
silently negated:

SELECT to_timestamp('2024-01-01 -1', 'YYYY-MM-DD SSSSS');
-- 2024-01-01 00:00:01+00 (-1 second becomes +1 second)
2. RM (Roman month numeral, documented I..XII) — out-of-range numeral
accepted:

SELECT to_date('2024 XIII', 'YYYY RM');
-- 2024-12-01 (XIII parsed as month 12)
3. IW (ISO week, documented 01-53) — values 54-99 accepted, silently
spilling into the following year. The sister field WW validates the same
value correctly:

SELECT to_date('2024 54', 'IYYY IW');
-- 2025-01-06 (no error)
SELECT to_date('2024 99', 'IYYY IW');
-- 2025-11-17 (no error)

SELECT to_date('2024 54', 'YYYY WW');
-- ERROR: date/time field value out of range: "2024 54"
4. ID (ISO day of week, documented 1-7) — both 0 and 8 accepted, each mapped
to Sunday:

SELECT to_date('2024 01 8', 'IYYY IW ID');
-- 2024-01-07 (should be an error)
SELECT to_date('2024 01 0', 'IYYY IW ID');
-- 2024-01-07 (same Sunday result as 7)
Expected behavior
Each field should raise date/time field value out of range for input outside
its documented domain, consistently with how DDD (367+), WW (54+), MM (13+),
DD (32+) and others already behave.

Responses

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