From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com> |
Cc: | Joseph Koshakow <koshy44(at)gmail(dot)com>, pgsql-hackers(at)lists(dot)postgresql(dot)org |
Subject: | Re: Extract epoch from Interval weird behavior |
Date: | 2022-04-08 13:10:46 |
Message-ID: | 3621530.1649423446@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com> writes:
> We really wanted to avoid doing calculations in numeric as much as
> possible. So we should figure out a different way to write this. The
> attached patch works for me. It's a bit ugly since it hardcodes some
> factors. Maybe we can rephrase it a bit more elegantly.
I think it's fine but needs some commentary. Maybe about like
"To do this calculation in integer arithmetic even though
DAYS_PER_YEAR is fractional, multiply everything by 4
and then divide by 4 again at the end. This relies on
DAYS_PER_YEAR being a multiple of 0.25 and on SECS_PER_DAY
being a multiple of 4."
BTW, it might be good to parenthesize as
(... big calculation ...) * (SECS_PER_DAY/4)
to eliminate any question of whether the value could overflow
before the final division by 4.
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Robert Haas | 2022-04-08 13:12:40 | Re: Support logical replication of DDLs |
Previous Message | Magnus Hagander | 2022-04-08 13:04:18 | Re: Mark all GUC variable as PGDLLIMPORT |