Tom Lane <tgl@sss.pgh.pa.us> writes:
> "Gavin M. Roy" <gmr@justsportsusa.com> writes:
> > SELECT * FROM poetry ORDER BY random() LIMIT 1;
> > [ is slow for 35000 rows ]
>
> Yeah. Basically this query is implemented as
> (a) select all 35000 rows of "poetry";
> (b) compute a random() value for each row;
> (c) sort by the random() values;
> (d) take the first row, discard the rest.
If you can generate a random value from your application layer you could do
select * from poetry LIMIT 1 OFFSET <random value>
Can offset values be placeholders in prepared queries? If not then this has
that disadvantage.
--
greg
