>Sean Wrote ===
>I'm considering using SQLLite for an embedded project. Some of the
data I'd like to store is timestamped sensor readings. I'd like to know
if there is a way to >configure a table so that it acts like a fixed
length FIFO queue, e.g. stores 10,000 records then once full drops off
the oldest record each time a new one is inserted.
.>Can anyone tell me if we can do that with SQLLite?
=====
You could use a simple trigger (example for queue of size 10000 below)
and a self-incrementing key column:
create table myqueue (limit_id integer not null primary key, myvalue
integer) ;
create trigger queue_limit after insert on myqueue
begin
update myqueue set limit_id = limit_id-1 where (select
max(limit_id) from myqueue ) > 10000;
delete from myqueue where limit_id <=0 ;
end ;
INSERT TO MYQUEUE:
insert into myqueue (myvalue) values (1) ;
insert into myqueue (myvalue) values(2) ;
......
insert into myqueue (myvalue) values (10050) ;
RESULTS:
limit_id myvalue
1 51
2 52
.....
10000 10050
Note: Its not very efficient.
Regards,
Eli
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