| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Randall Skelton <skelton(at)brutus(dot)uwaterloo(dot)ca> |
| Cc: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: returning row numbers in select |
| Date: | 2004-03-10 23:01:44 |
| Message-ID: | 13737.1078959704@sss.pgh.pa.us |
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| Lists: | pgsql-general |
Randall Skelton <skelton(at)brutus(dot)uwaterloo(dot)ca> writes:
>> Couldn't you code this as a WHERE test on the timestamp?
> That would be ideal as it is theoretically possible for there to be
> missing rows due to sampling errors; nevertheless, a WHERE test doesn't
> seem obvious to me. Can you please post an example?
Something like
WHERE (EXTRACT(EPOCH FROM timestamp)::numeric % 5) = 0;
The EXTRACT function returns double precision, but there's no double
modulo operator for some reason, hence the cast to numeric which does
have one.
regards, tom lane
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