Re: flagging first row inserted for each "group" of key

In response to Ivan Sergio Borgonovo :
> I've a web application.
>
> I'm logging data related to the landing page and subsequent selected
> hits.
>
> create table track_hit (
> hitid serial not null,
> /* pk? I don't mind if serial wrap around
> pk could be (hitid, tracking_time) */
> esid varchar(32), -- related to session
> tracking_time timestamp not null default now(),
> -- some other stats
> -- first_hit boolean not null default false, -- ???
> );
>
> I'd like to be sure I just count one "first hit" in a session (same
> esid) in an efficient way that means I'd like to mark them with a

select distinct on (esid) esid, tracking_time from track_hit order by esid, tracking_time;

returns only one record for each esid, ordered by tracking_time. Should
work with 8.x, maybe sice 7.x (I'm not sure)

HTH, Andreas
--
Andreas Kretschmer
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