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help / color / mirror / Atom feedFrom: Heikki Linnakangas <heikki.linnakangas@iki.fi>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: seg: Fix seg_out() to preserve the upper boundary's certainty in
Date: Thu, 11 Jun 2026 09:43:56 +0000
Message-ID: <E1wXbx6-001zJd-2F@gemulon.postgresql.org> (raw)
seg: Fix seg_out() to preserve the upper boundary's certainty indicator
When printing the upper boundary of a seg interval, seg_out() decided
whether to emit the certainty indicator ('<', '>' or '~') by testing the
upper indicator (u_ext) for '<' and '>', but mistakenly tested the lower
indicator (l_ext) for '~'. This is a copy-and-paste slip from the
symmetric code that prints the lower boundary a few lines above.
The consequences for valid input were:
* A '~' on the upper boundary was dropped on output, e.g.
'1.5 .. ~2.5'::seg printed as '1.5 .. 2.5'.
* When the lower boundary carried '~' but the upper boundary had no
indicator, the wrong test matched and sprintf(p, "%c", seg->u_ext)
wrote a NUL byte (u_ext == '\0'), which truncated the result string
and silently lost the entire upper boundary, e.g.
'~6.5 .. 8.5'::seg printed as '~6.5 .. '.
Certainty indicators are documented to be preserved on output (they are
ignored by the operators, but kept as comments), so this broke the
input/output round-trip for the affected values.
The bug has existed since seg was added. It went unnoticed because the
existing regression tests only exercised certainty indicators on
single-point segs, which are printed by a different branch of seg_out().
Add tests that place indicators on both boundaries of an interval.
Author: Ewan Young <kdbase.hack@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAON2xHPYeRRCEVAv8XfE18KsEsEHCiYcJ5fOsoxFuMEfpxF1=g@mail.gmail...
Backpatch-through: 14
Branch
------
REL_17_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/bcbbd070d4961aa4c2f983bdbcf488c0c0d752a1
Modified Files
--------------
contrib/seg/expected/seg.out | 45 +++++++++++++++++++++++++++++++++++++++++++-
contrib/seg/seg.c | 2 +-
contrib/seg/sql/seg.sql | 11 ++++++++++-
3 files changed, 55 insertions(+), 3 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: heikki.linnakangas@iki.fi, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: seg: Fix seg_out() to preserve the upper boundary's certainty in
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