Re: some points for FAQ

Pavel Stehule wrote:
> 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

Right. We really only want general solutions in the FAQ.

> > > 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.

OK, let's see how many bug reports we get and we can always re-add it.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://postgres.enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +