shulkae <shulkae@gmail.com> writes:
> I am newbie to postgres/SQL.
>
> I want to delete all rows exceeding 400 hours (10 days) and I want to
> limit deletion of only 100 records at a time.
>
> I was trying the following in PostgreSQL:
>
> DELETE from mytable WHERE (now() - timestamp_field > INTERVAL '400
> hour' ) LIMIT 100;
>
> Looks like DELETE syntax doesn't support LIMIT.
>
> Is there any other way to achieve this?
Sure...
Supposing mytable has, as a unique key, column "id"...
delete from mytable where id in (select id from mytable where timestamp_field < now() - '400
hours'::interval limit 100);
I once set up a process where I did this exact sort of thing, complete
with a "back-off" scheme where each iteration would check a sequence to
see if a lot of new tuples had come in since last time, and:
a) If the system was looking busy, it would only delete a small bit of data; b) If the system was not busy at all,
itwould delete quite a bit more obsolete data.
--
output = reverse("ofni.secnanifxunil" "@" "enworbbc")
Signs of a Klingon Programmer #1: "Our users will know fear and cower
before our software. Ship it! Ship it and let them flee like the dogs
they are!"
