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Thread: Transactions and timestamps

Transactions and timestamps

From
Daniel Åkerud
Date:
 
If I do
 
BEGIN
UPDATE some_session set time_stop = CURRENT_TIMESTAMP
UPDATE another_session set time_start = CURRENT_TIMESTAMP
END
 
Is there any chance the current_timestamp will be different?
 
Do I have to first select current_timestamp and then update with a variable? (function?)
 
---
Daniel Åkerud
 
[ Don't underestimate the power of stupid people in large groups]

Re: Transactions and timestamps

From
"Richard Huxton"
Date:
Please don't post HTML to the mailing list - it makes quoting difficult...


From: "Daniel Åkerud" <zilch@home.se>

If I do

BEGIN
UPDATE some_session set time_stop = CURRENT_TIMESTAMP
UPDATE another_session set time_start = CURRENT_TIMESTAMP
END

Is there any chance the current_timestamp will be different?

=reply=

If you try your example by hand (with a suitable pause) you'll see
CURRENT_TIMESTAMP and the now() function return the time at the start of the
transaction. You use timeofday() IIRC to get the "real" current time.

HTH

- Richard Huxton

Re: Transactions and timestamps

From
Tom Lane
Date:
=?iso-8859-1?Q?Daniel_=C5kerud?= <zilch@home.se> writes:
> If I do

> BEGIN
> UPDATE some_session set time_stop =3D CURRENT_TIMESTAMP
> UPDATE another_session set time_start =3D CURRENT_TIMESTAMP
> END

> Is there any chance the current_timestamp will be different?

No.  CURRENT_TIMESTAMP is actually the time of the start of the
transaction.

            regards, tom lane