Обсуждение: values from now() in the same transaction
I created a function with VOLATILE directive. it's body looks like shown bellow ------------------------ cut start begin insert into monitor(ts, c1) values(LOCALTIMESTAMP, 'Step 1000'); -- start time -- query below runs for 20min insert ito t1 select * from big_table -- this timestamp should be bigger by 20min than start time insert into monitor(ts, c1) values(LOCALTIMESTAMP, 'Step 1001'); end ----------------------- cut end The value returned by LOCALTIMESTAMP function is the same in both places despite that actual interval of 20 min between these calls. I tried function now(),current_timestamp() but all of them behave similar. I don't believe that it's bug, probably it's a feature of the postgreSql database. Is any way to insert a timestamp within the same transaction that would have current system time (not time of the beginning of the transaction)? With other words, I would like to see different timestamps on first and last timestamp. Thank you, Vladimir
Vladimir Zelinski wrote: > I don't believe that it's bug, probably it's a feature > of the postgreSql database. Correct. > Is any way to insert a timestamp within the same > transaction that would have current system time (not > time of the beginning of the transaction)? timeofday() -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support
Thank you very much. It works. Vladimir --- Alvaro Herrera <alvherre@commandprompt.com> wrote: > Vladimir Zelinski wrote: > > > I don't believe that it's bug, probably it's a > feature > > of the postgreSql database. > > Correct. > > > Is any way to insert a timestamp within the same > > transaction that would have current system time > (not > > time of the beginning of the transaction)? > > timeofday() > > -- > Alvaro Herrera > http://www.CommandPrompt.com/ > PostgreSQL Replication, Consulting, Custom > Development, 24x7 support > > ---------------------------(end of > broadcast)--------------------------- > TIP 4: Have you searched our list archives? > > http://archives.postgresql.org/ >
zelvlad@yahoo.com (Vladimir Zelinski) writes:
> I tried function now(),current_timestamp() but all of
> them behave similar.
>
> I don't believe that it's bug, probably it's a feature
> of the postgreSql database.
Indeed, that is intentional. CURRENT_TIMESTAMP and NOW() return the
time at which the transaction began.
> Is any way to insert a timestamp within the same transaction that
> would have current system time (not time of the beginning of the
> transaction)?
> With other words, I would like to see different timestamps on first
> and last timestamp.
timeofday() is what you are looking for.
Consider the following series of queries; they demonstrate how the
behaviours of now() and timeofday() differ fairly successfully...
oxrsorg=# begin;
BEGIN
oxrsorg=# select now();
now
-------------------------------
2007-02-16 23:23:23.094817+00
(1 row)
oxrsorg=# select timeofday();
timeofday
-------------------------------------
Fri Feb 16 23:23:31.481780 2007 UTC
(1 row)
oxrsorg=# select timeofday();
timeofday
-------------------------------------
Fri Feb 16 23:23:32.981137 2007 UTC
(1 row)
oxrsorg=# select timeofday();
timeofday
-------------------------------------
Fri Feb 16 23:23:33.988252 2007 UTC
(1 row)
oxrsorg=# select now();
now
-------------------------------
2007-02-16 23:23:23.094817+00
(1 row)
oxrsorg=# select timeofday();
timeofday
-------------------------------------
Fri Feb 16 23:23:38.643998 2007 UTC
(1 row)
oxrsorg=# select now();
now
-------------------------------
2007-02-16 23:23:23.094817+00
(1 row)
--
(reverse (concatenate 'string "ofni.secnanifxunil" "@" "enworbbc"))
http://linuxfinances.info/info/finances.html
Rules of the Evil Overlord #189. "I will never tell the hero "Yes I
was the one who did it, but you'll never be able to prove it to that
incompetent old fool." Chances are, that incompetent old fool is
standing behind the curtain." <http://www.eviloverlord.com/>
The problem with gettimeofday() is that it returns a string, rather than
a timestamp. This was all clarified in 8.2:
Add clock_timestamp(), statement_timestamp(), and
transaction_timestamp() (Bruce)
clock_timestamp() is the current wall-clock time,
statement_timestamp() is the time the current statement arrived at
the server, and transaction_timestamp() is an alias for now().
---------------------------------------------------------------------------
Chris Browne wrote:
> zelvlad@yahoo.com (Vladimir Zelinski) writes:
> > I tried function now(),current_timestamp() but all of
> > them behave similar.
> >
> > I don't believe that it's bug, probably it's a feature
> > of the postgreSql database.
>
> Indeed, that is intentional. CURRENT_TIMESTAMP and NOW() return the
> time at which the transaction began.
>
> > Is any way to insert a timestamp within the same transaction that
> > would have current system time (not time of the beginning of the
> > transaction)?
>
> > With other words, I would like to see different timestamps on first
> > and last timestamp.
>
> timeofday() is what you are looking for.
>
> Consider the following series of queries; they demonstrate how the
> behaviours of now() and timeofday() differ fairly successfully...
>
> oxrsorg=# begin;
> BEGIN
> oxrsorg=# select now();
> now
> -------------------------------
> 2007-02-16 23:23:23.094817+00
> (1 row)
>
> oxrsorg=# select timeofday();
> timeofday
> -------------------------------------
> Fri Feb 16 23:23:31.481780 2007 UTC
> (1 row)
>
> oxrsorg=# select timeofday();
> timeofday
> -------------------------------------
> Fri Feb 16 23:23:32.981137 2007 UTC
> (1 row)
>
> oxrsorg=# select timeofday();
> timeofday
> -------------------------------------
> Fri Feb 16 23:23:33.988252 2007 UTC
> (1 row)
>
> oxrsorg=# select now();
> now
> -------------------------------
> 2007-02-16 23:23:23.094817+00
> (1 row)
>
> oxrsorg=# select timeofday();
> timeofday
> -------------------------------------
> Fri Feb 16 23:23:38.643998 2007 UTC
> (1 row)
>
> oxrsorg=# select now();
> now
> -------------------------------
> 2007-02-16 23:23:23.094817+00
> (1 row)
>
>
> --
> (reverse (concatenate 'string "ofni.secnanifxunil" "@" "enworbbc"))
> http://linuxfinances.info/info/finances.html
> Rules of the Evil Overlord #189. "I will never tell the hero "Yes I
> was the one who did it, but you'll never be able to prove it to that
> incompetent old fool." Chances are, that incompetent old fool is
> standing behind the curtain." <http://www.eviloverlord.com/>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Have you searched our list archives?
>
> http://archives.postgresql.org/
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 02/16/07 17:25, Chris Browne wrote: > zelvlad@yahoo.com (Vladimir Zelinski) writes: >> I tried function now(),current_timestamp() but all of >> them behave similar. >> >> I don't believe that it's bug, probably it's a feature >> of the postgreSql database. > > Indeed, that is intentional. CURRENT_TIMESTAMP and NOW() return the Ooooh, is that Standard Behavior? Is there a standard definition for CURRENT_TIMESTAMP? -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFF1k91S9HxQb37XmcRAqFsAKCMI+xzFxig2XMDPcsWcRMfToOJ/QCffWwO iLBhZIc3jGp2VWwVSxW7hRQ= =RTIl -----END PGP SIGNATURE-----