Subject: pgsql: Improve overflow/underflow handling in regr_r2().

From: Dean Rasheed <[email-masked]>
Date: Wed, 03 Jun 2026 08:03:37 +0000

Improve overflow/underflow handling in regr_r2().

Commit 6498287696d improved corr()'s final function to cope with
overflow/underflow in the final calculation, and clamped its result to
[-1, 1] in case of roundoff error. Improve regr_r2() in a similar way,
clamping its result to [0, 1].

Arguably this is a bug fix, but given the lack of prior complaints,
refrain from back-patching, as we did with 6498287696d.

Reported-by: Chengpeng Yan <[email-masked]>
Author: Chengpeng Yan <[email-masked]>
Reviewed-by: Dean Rasheed <[email-masked]>
Reviewed-by: Tom Lane <[email-masked]>
Discussion: https://postgr.es/m/[email-masked]

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/d58ec50e0faae364fa59cdb88eba7e23b55ab583

Modified Files
--------------
src/backend/utils/adt/float.c            | 37 ++++++++++++++++++--
src/test/regress/expected/aggregates.out | 58 +++++++++++++++++++++-----------
src/test/regress/sql/aggregates.sql      | 19 ++++++++---
3 files changed, 87 insertions(+), 27 deletions(-)