PostgreSQL Hacks - Strange results from to

Author

Strange results from to_timestamp

Mario Weilguni

2006-04-06, 9:34 am

mydb=# select to_timestamp('000000
00 0300','yyyymmdd hh24mi');
to_timestamp
---------------------------
0001-01-01 03:00:00+01 BC
(1 row)

Questionable, but probably valid.

mydb=# select to_timestamp(' 0300','yyyymmdd hh24mi');
to_timestamp
------------------------
0300-12-25 03:00:00+01
(1 row)

This puzzles me. Where is the 25th of december coming from?

mydb=# select to_timestamp(' 030004','yyyymmdd hh24mi');
to_timestamp
------------------------
0382-04-23 03:00:00+01
(1 row)

Same as above.

mydb=# select to_timestamp(' 040004','yyyymmdd hh24mi');
to_timestamp
------------------------
0509-10-10 04:00:00+01

I think all except the first one should raise a warning, isn't it? Where can I
find the source code of this function?

Best regards,
Mario Weilguni

---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match

Mario Weilguni

2006-04-06, 9:34 am

Am Donnerstag, 6. April 2006 14:57 schrieb Mario Weilguni:
> mydb=# select to_timestamp('000000
00 0300','yyyymmdd hh24mi');
> to_timestamp
> ---------------------------
> 0001-01-01 03:00:00+01 BC
> (1 row)
>
> Questionable, but probably valid.
>
>
>
> mydb=# select to_timestamp(' 0300','yyyymmdd hh24mi');
> to_timestamp
> ------------------------
> 0300-12-25 03:00:00+01
> (1 row)
>
> This puzzles me. Where is the 25th of december coming from?

Sorry, forgot to mention, this is from PostgreSQL 8.1.3

---------------------------(end of broadcast)---------------------------
TIP 6: explain analyze is your friend

William ZHANG

2006-04-06, 11:32 am

ISTM, and mismatch between the date/time string and the format string will
lead to
strange results.
The source code of to_timestamp() is in src/backend/utils/adt/formatting.c:

Datum
to_timestamp(PG_FUNC
TION_ARGS)

Regards,
William ZHANG

"Mario Weilguni" <mweilguni@sime.com>
> Am Donnerstag, 6. April 2006 14:57 schrieb Mario Weilguni:
>
> Sorry, forgot to mention, this is from PostgreSQL 8.1.3
>
> ---------------------------(end of broadcast)---------------------------
> TIP 6: explain analyze is your friend
>

Tom Lane

2006-04-07, 3:42 am

Mario Weilguni <mweilguni@sime.com> writes:
> I think all except the first one should raise a warning, isn't it?

to_timestamp (and friends) all seem to me to act pretty bizarre when
faced with input that doesn't match the given format string. However,
in the end that is an Oracle-compatibility function, and there is only
one measure of what it should do: what does Oracle do in the same case.
Can anyone try these examples on a recent Oracle version?

regards, tom lane

---------------------------(end of broadcast)---------------------------
TIP 3: Have you checked our extensive FAQ?

http://www.postgresql.org/docs/faq

Adrian Maier

2006-04-07, 9:34 am

On 4/7/06, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Mario Weilguni <mweilguni@sime.com> writes:
>
> to_timestamp (and friends) all seem to me to act pretty bizarre when
> faced with input that doesn't match the given format string. However,
> in the end that is an Oracle-compatibility function, and there is only
> one measure of what it should do: what does Oracle do in the same case.
> Can anyone try these examples on a recent Oracle version?

In Oracle10g Express those dates are rejected as invalid :

SQL> select to_timestamp('000000
00 0300','yyyymmdd hh24mi') from dual;
select to_timestamp('000000
00 0300','yyyymmdd hh24mi') from dual
*
ERROR at line 1:
ORA-01843: not a valid month

SQL> select to_timestamp(' 0300','yyyymmdd hh24mi') from dual;
select to_timestamp(' 0300','yyyymmdd hh24mi') from dual
*
ERROR at line 1:
ORA-01843: not a valid month

Cheers,
Adrian Maier

---------------------------(end of broadcast)---------------------------
TIP 5: don't forget to increase your free space map settings

Mario Weilguni

2006-04-07, 9:34 am

to_timestamp is only for Oracle compatibility? I always thought it's some sort of sql standard. What's the sql compliant way to do this?

Regards,
mario weilguni

-----Ursprüngliche Nachricht-----
Von: pgsql-hackers-owner@postgresql.org [mailto:pgsql-hackers-owner@postgresql.org] Im Auftrag von Tom Lane
Gesendet: Freitag, 07. April 2006 06:09
An: Mario Weilguni
Cc: PostgreSQL-development
Betreff: Re: [HACKERS] Strange results from to_timestamp

Mario Weilguni <mweilguni@sime.com> writes:
> I think all except the first one should raise a warning, isn't it?

to_timestamp (and friends) all seem to me to act pretty bizarre when faced with input that doesn't match the given format string. However, in the end that is an Oracle-compatibility function, and there is only one measure of what it should do: what does
Oracle do in the same case.
Can anyone try these examples on a recent Oracle version?

regards, tom lane

---------------------------(end of broadcast)---------------------------
TIP 3: Have you checked our extensive FAQ?

http://www.postgresql.org/docs/faq

---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match

Sponsored Links