Re: pgsql/src/backend/nodes (copyfuncs.c outfuncs.c print.c)

Tom Lane wrote:

> Hiroshi Inoue <Inoue@tpf.co.jp> writes:
> > begin;
> > declare myc cursor for select * from t1 limit all;
> > fetch 20 in myc; (the first page)
> > ...(interaction)
> > fetch 20 in myc; (the next page)
> > ..(interaction)
> > fetch backward 20 in myc; (the previous page)
> > ...
>
> > What I expect here is to get rows of each page in
> > an average response time not the total throughput
> > of db operation.
>
> Yes, but why should the presence of "limit all" affect that?
> It's not apparent to me why the optimizer should treat this
> case differently from plain
> declare myc cursor for select * from t1;
>

Am I misunderstanding ?
Doesn't optimizer make the plan for the query
"select * for t1" which would use SeqScan
in most cases ?

Regards, Hiroshi Inoue