Re: ODBC Layer and the now() function

Hi,

I hope the following link will help you.

http://www.postgresql.org/docs/8.0/static/plpgsql-expressions.html

On 12/5/05, Byrne Kevin-kbyrne01 <kbyrne01(at)motorola(dot)com> wrote:
>
> Has anyone seen any strange behaviour as regards the now() function when
> accessing a db via odbc layer. The behaviour I have seen (which I have
> mentioned in pervious post) is as follows:
>
> I have a trigger set up on a db - when a row is added to a certain table
> (say Table A) in my db the trigger calls a function and then the function
> enters another line in a related table (say Table B). Here's the problem,
> the first addition to Table A may shows the time of the addition as, for
> example 19:01:53. This is correct. The second addition, triggered by the
> first additon, shows a time of say 19:01:10! The addition of the row to
> Table B uses the now() function to determine the time the new row is added
> to the table. This should in theory match the time (to within a few
> milliseconds at least) the first row was added, since the trigger is
> immediate. However, I am seeing major time differences?
>
> For the first table, Table A, timestamp is obtained using timeofday. As
> mentioned the second table uses now(). There is a possibility that these two
> times will differ slightly. However, I do not understand why the time of
> entry into the second table could be earlier than the first table!? i.e.
>
> Moserver receives the event - timestamps it as 't1'
> -- time lapse before moserver computes the transaction and gives it to
> odbc.
> Txn_begin- now() gets frozen to 't2'
> Insert - now() should put it as 't2'
> Txn_end()- done.
>
> So firstly t2 should always be > t1 and the difference could be a few
> seconds but I found sometimes t2 < t1!..
>
>
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