Re: would it be a lot of work, to add optimizations accross unions ?

Grzegorz Jaskiewicz <gj@pointblue.com.pl> writes:

> On 28 Feb 2009, at 11:37, Gregory Stark wrote:
>>
>> I posted a patch to look for an ordered path for members of a union  a while
>> back but it still needed a fair amount of work before it was usable.
>>
> I belive limit it self can't be pushed down, but with order by - why  not ? 

Because my patch wasn't finished? There were still things about the planner I
didn't understand which blocked me from finishing it at the time.

>>> select foo( select foo from bar1 ) a where foo in (x,y,z) order by  foo
>>> desc
>>> limit N
>>
>> huh?
> Just a simple example, perhaps oversimplified.
> The thing is, in case like that - planner could merge two queries  together.

No, I meant I don't understand what you're trying to do with this query or
what you would propose the planner should do with it. Afaict this isn't a
valid query at all and I don't see two queries to merge in it.

--  Gregory Stark EnterpriseDB          http://www.enterprisedb.com Ask me about EnterpriseDB's 24x7 Postgres support!