From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Gregory Stark <stark(at)mit(dot)edu> |
Cc: | Postgres <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: date_part()/EXTRACT(second) behaviour with time data type |
Date: | 2009-07-29 16:15:42 |
Message-ID: | 19958.1248884142@sss.pgh.pa.us |
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Gregory Stark <stark(at)mit(dot)edu> writes:
> I think we broke date_part for extracting seconds from time arguments. It
> appears we leave out the milliseconds whereas we don't for timestamp
> arguments. This was not the case in 8.3 where we included the milliseconds for
> both data types.
It's not new. This appears to be a difference between the integer and
float timestamp code paths, and I'd say it's probably a thinko:
case DTK_SECOND:
#ifdef HAVE_INT64_TIMESTAMP
result = tm->tm_sec + fsec / USECS_PER_SEC;
#else
result = tm->tm_sec + fsec;
#endif
break;
In the integer case, fsec is an integer and so the division loses the
fraction. timestamptz_part does this instead:
case DTK_SECOND:
#ifdef HAVE_INT64_TIMESTAMP
result = tm->tm_sec + fsec / 1000000.0;
#else
result = tm->tm_sec + fsec;
#endif
break;
I agree that we should change it, but should we back-patch it, and if so
how far?
regards, tom lane
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