From: Robert Haas <rhaas@postgresql.org>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Don't set the truncation block length greater than RELSEG_SIZE.
Date: Mon, 19 Jan 2026 17:41:43 +0000
Message-ID: <E1vhtG2-001Rc6-1i@gemulon.postgresql.org> (raw)
Don't set the truncation block length greater than RELSEG_SIZE.
When faced with a relation containing more than 1 physical segment
(i.e. >1GB, with normal settings), the previous code could compute a
truncation block length greater than RELSEG_SIZE, which could lead to
restore failures of this form:
file "%s" has truncation block length %u in excess of segment size %u
The fix is simply to clamp the maximum computed truncation_block_length
to RELSEG_SiZE. I have also added some comments to clarify the logic.
The test case was written by Oleg Tkachenko, but I have rewritten its
comments.
Reported-by: Oleg Tkachenko <oatkachenko@gmail.com>
Diagnosed-by: Oleg Tkachenko <oatkachenko@gmail.com>
Co-authored-by: Robert Haas <rhaas@postgresql.org>
Co-authored-by: Oleg Tkachenko <oatkachenko@gmail.com>
Reviewed-by: Amul Sul <sulamul@gmail.com>
Backpatch-through: 17
Discussion: http://postgr.es/m/00FEFC88-EA1D-4271-B38F-EB741733A84A@gmail.com
Branch
------
REL_18_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/c80b0c9d63b25a1e7fc751a4cf66a6510ffafbb8
Modified Files
--------------
src/backend/backup/basebackup_incremental.c | 14 +++
src/bin/pg_combinebackup/meson.build | 1 +
.../t/011_incremental_backup_truncation_block.pl | 101 +++++++++++++++++++++
3 files changed, 116 insertions(+)
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To: pgsql-committers@postgresql.org
Cc: rhaas@postgresql.org, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Don't set the truncation block length greater than RELSEG_SIZE.
In-Reply-To: <E1vhtG2-001Rc6-1i@gemulon.postgresql.org>
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