Re: some points for FAQ

2007/10/9, Bruce Momjian <bruce(at)momjian(dot)us>:
> Pavel Stehule wrote:
> > 4.1)
> >
> > To SELECT a random row, use:
> > SELECT col
> > FROM tab
> > ORDER BY random()
> > LIMIT 1;
> >
> > + On bigger tables this solution is slow. Please, find smarter
> > solution on network.
> >
>
> Well, give me a better example that works.

Better universal solution doesn't exist. Exists only unelegant
solutions - but mutch faster.

SELECT id, ...
FROM data
WHERE id = ANY(ARRAY(
SELECT (random()*:max_id)::int
FROM generate_series(1,20)))
LIMIT 1;

max_id is host variable ~ real max id + some

-- fast solution if id is PK of data

>
> > 4.19)
> >
> > + most of problems with invalid OIDs in cache are solved in PostgreSQL
> > 8.3. Please remeber, so every replanning of SQL statements needs time.
> > Write your application, they can exist without cache invalidation.
>
> Agreed. Item removed.
>

Cache invalidation isn't 100% protection before this error message.
With specific using of EXECUTE statement, you can get this message
too. But all temp tables related problems are solved.

Regards
Pavel Stehule