Обсуждение: Re: [HACKERS] subselects

Bruce Momjian wrote:
>
> OK, a few questions:
>
>         Should we use sortmerge, so we can use our psort as temp tables,
> or do we use hashunique?
>
>         How do we pass the query to the optimizer?  How do we represent
> the range table for each, and the links between them in correlated
> subqueries?

My suggestion is just use varlevel in Var and don't put upper query'
relations into subquery range table.

Vadim

Vadim B. Mikheev wrote:
>
> Bruce Momjian wrote:
> >
> > OK, a few questions:
> >
> >         Should we use sortmerge, so we can use our psort as temp tables,
> > or do we use hashunique?
> >
> >         How do we pass the query to the optimizer?  How do we represent
> > the range table for each, and the links between them in correlated
> > subqueries?
>
> My suggestion is just use varlevel in Var and don't put upper query'
> relations into subquery range table.

Hmm... Sorry, it seems that I did reply to very old message - forget it.

Vadim

>
> Bruce Momjian wrote:
> >
> > OK, a few questions:
> >
> >         Should we use sortmerge, so we can use our psort as temp tables,
> > or do we use hashunique?
> >
> >         How do we pass the query to the optimizer?  How do we represent
> > the range table for each, and the links between them in correlated
> > subqueries?
>
> My suggestion is just use varlevel in Var and don't put upper query'
> relations into subquery range table.
>
> Vadim
>

OK.

--
Bruce Momjian
maillist@candle.pha.pa.us