Re: [HACKERS] Solution for LIMIT cost estimation - Mailing list pgsql-hackers

From Tom Lane
Subject Re: [HACKERS] Solution for LIMIT cost estimation
Date
Msg-id 2920.950715815@sss.pgh.pa.us
Whole thread Raw
In response to Re: [HACKERS] Solution for LIMIT cost estimation  (Philip Warner <pjw@rhyme.com.au>)
Responses Re: [HACKERS] Solution for LIMIT cost estimation
RE: [HACKERS] Solution for LIMIT cost estimation
List pgsql-hackers
Philip Warner <pjw@rhyme.com.au> writes:
>> A possible answer is to define OFFSET/LIMIT in DECLARE CURSOR as
>> being simply a hint to the optimizer about how much of the query
>> result will actually get fetched.  

> This seems a good approach until cursors are fixed. But is there a plan to
> make cursors support LIMIT properly? Do you know why they ignore the LIMIT
> clause?

Should they obey LIMIT?  MOVE/FETCH seems like a considerably more
flexible interface, so I'm not quite sure why anyone would want to
use LIMIT in a cursor.

Still, it seems kind of inconsistent that cursors ignore LIMIT.
I don't know for sure why it was done that way.
        regards, tom lane


pgsql-hackers by date:

Previous
From: Tom Lane
Date:
Subject: Re: [HACKERS] TODO: Cache most recent query plan
Next
From: Thomas Lockhart
Date:
Subject: Re: [HACKERS] Almost there on column aliases