| From: | Richard Neill <rn214(at)cam(dot)ac(dot)uk> |
|---|---|
| To: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov> |
| Cc: | pgsql-bugs(at)postgresql(dot)org |
| Subject: | Re: BUG #5293: constant function (date_trunc) is repeatedly evaluated inside loop |
| Date: | 2010-01-20 16:56:16 |
| Message-ID: | 4B5735B0.7050106@cam.ac.uk |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-bugs |
Kevin Grittner wrote:
> "Richard Neill" <rn214(at)cam(dot)ac(dot)uk> wrote:
>
>> date_trunc('day', timestamp '2010-01-20 10:16:55')
>
> What happens with a "timestamp with time zone" literal?
>
> -Kevin
>
Good call!
This query is fast:
SELECT count(1) FROM tbl_tracker WHERE ((srep_timestamp >=
date_trunc('day', timestamp with time zone '2010-01-20 10:16:55') AND
srep_timestamp < date_trunc('day', timestamp with time zone '2010-01-20
10:16:55') + INTERVAL '24 hour' )) ;
In other words:
#fast
WHERE column < '2010-010-20 00:00:00'
#fast
WHERE column < date_trunc('day', timestamp with time zone
'2010-01-20 10:16:55')
#slow
WHERE column < date_trunc('day', timestamp
'2010-01-20 10:16:55')
Why is that, I wonder?
Richard
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Kevin Grittner | 2010-01-20 17:04:09 | Re: BUG #5293: constant function (date_trunc) is repeatedly evaluated inside loop |
| Previous Message | Kevin Grittner | 2010-01-20 15:21:46 | Re: BUG #5292: Corrupted installer |