From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | pgsql-committers(at)lists(dot)postgresql(dot)org |
Subject: | pgsql: Fix behavior of float aggregates for single Inf or NaN inputs. |
Date: | 2020-06-13 17:43:58 |
Message-ID: | E1jkACE-0002QO-8g@gemulon.postgresql.org |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-committers |
Fix behavior of float aggregates for single Inf or NaN inputs.
When there is just one non-null input value, and it is infinity or NaN,
aggregates such as stddev_pop and covar_pop should produce a NaN
result, because the calculation is not well-defined. They used to do
so, but since we adopted Youngs-Cramer aggregation in commit e954a727f,
they produced zero instead. That's an oversight, so fix it. Add tests
exercising these edge cases.
Affected aggregates are
var_pop(double precision)
stddev_pop(double precision)
var_pop(real)
stddev_pop(real)
regr_sxx(double precision,double precision)
regr_syy(double precision,double precision)
regr_sxy(double precision,double precision)
regr_r2(double precision,double precision)
regr_slope(double precision,double precision)
regr_intercept(double precision,double precision)
covar_pop(double precision,double precision)
corr(double precision,double precision)
Back-patch to v12 where the behavior change was accidentally introduced.
Report and patch by me; thanks to Dean Rasheed for review.
Discussion: https://postgr.es/m/353062.1591898766@sss.pgh.pa.us
Branch
------
REL_12_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/874372a941a6ee31ba4034db0367e0929e5f49bc
Modified Files
--------------
src/backend/utils/adt/float.c | 35 +++++++++++
src/test/regress/expected/aggregates.out | 105 ++++++++++++++++++++++++++++++-
src/test/regress/sql/aggregates.sql | 21 ++++++-
3 files changed, 159 insertions(+), 2 deletions(-)
From | Date | Subject | |
---|---|---|---|
Next Message | Tom Lane | 2020-06-13 18:01:53 | pgsql: Sync behavior of var_samp and stddev_samp for single NaN inputs. |
Previous Message | Peter Geoghegan | 2020-06-13 16:33:57 | pgsql: Silence _bt_check_unique compiler warning. |