Re: Duration between two timestamps

Steve Crawford wrote:

>On Friday 04 February 2005 7:37 am, you wrote:
>  
>
>>Hi All,
>>I have stored event records in Postgresql 7.3.4 and now need to
>>calculate the duration between each event in succession.  I have
>>"record_id" and a" timestamp without time zone" columns for each
>>event.
>>
>>What is a good way to calculate the difference in timestamp and
>>store it in the record as duration.  I am doing this as part of a
>>java application on RH linux 8.0.
>>
>>My timestamp is of the form "2005-01-30 07:51:29.149458".
>>thanks in advance,
>>Phil
>>    
>>
>
>How about:
>
>select (select min(eventtime) from foo b where b.eventtime > 
>a.eventtime)-eventtime from foo a;
>
>Obviously an index on eventtime is indicated but still this query does 
>have the potential to take a long time. It also assumes that event 
>timestamps are unique.
>
>If your timestamps can have the same value and the record_id is 
>monotonically increasing then you can use the same basic technique 
>with the record_id as the selector.
>
>Cheers,
>Steve
>
>
>  
>
Thanks Steve, Martin...I will give your ideas a try.
Phil