Re: [HACKERS] getting at the actual int4 value of an abstime

From: Thomas Lockhart <lockhart(at)alumni(dot)caltech(dot)edu>
To: Jim Mercer <jim(at)reptiles(dot)org>
Cc: "Ross J(dot) Reedstrom" <reedstrm(at)wallace(dot)ece(dot)rice(dot)edu>, pgsql-general(at)postgreSQL(dot)org, pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: [HACKERS] getting at the actual int4 value of an abstime
Date: 1999-08-18 06:34:41
Message-ID: 37BA5401.8C13B4EB@alumni.caltech.edu
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> > i have a table which uses an abstime to store a time/date.
> > the data originates as unix time_t
> > i want to get the results of a select as unix time_t, without having
> > to use the expensive mktime()/strptime() unix C calls.
> > is there a way to get the int4 value that postgres is storing raw
> > for abstime?

postgres=> select date_part('epoch', timefield) from timetest;
date_part
---------
934957840
(1 rows)

> test=> select timefield::int4 from timetest;
> ?column?
> ----------------------------
> Tue Aug 17 18:13:23 1999 CDT
> Hmm, this looks like a bug. I'm guessing we're storing and int8, and the
> conversion fails, so falls back to the default text output?

Probably not. Abstime is internally stored as 4 bytes, roughly the
same as int4, and so Postgres is swallowing the conversion since it
thinks they are equivalent. But the output conversion is not
equivalent.

> test=> select timefield::int8 from timetest;
> int8
> ---------
> 934931603
> What version of PostgreSQL, BTW? This is 6.5: int8 and numeric support got a
> lot better vs. 6.4

Trying to force a conversion to some other data type works, since the
conversion isn't swallowed by Postgres. The int4 behavior should count
as a bug...

- Thomas

--
Thomas Lockhart lockhart(at)alumni(dot)caltech(dot)edu
South Pasadena, California

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