Re: Changing SQL Inlining Behaviour (or...?) - Mailing list pgsql-hackers

From Paul Ramsey
Subject Re: Changing SQL Inlining Behaviour (or...?)
Date
Msg-id 3D6D6871-5F63-4C0D-AA18-91D5C4E43F3A@cleverelephant.ca
Whole thread Raw
In response to Re: Changing SQL Inlining Behaviour (or...?)  (Andres Freund <andres@anarazel.de>)
Responses Re: Changing SQL Inlining Behaviour (or...?)
List pgsql-hackers

> On Jan 21, 2019, at 3:27 PM, Andres Freund <andres@anarazel.de> wrote:
>
> Hi,
>
> On 2019-01-21 15:21:29 -0800, Paul Ramsey wrote:
>> As a practical matter, most of the exact-test functions have a
>> preamble that checks the bbox, so in the seqscan case having the
>> operator along for the ride isn’t any advantage. In any event, if we
>> do have exact tests w/o a lossy preamble, we could add that for v12,
>> as this renovation won’t be a small one if we go this direction.
>
> How expensive are the bbox checks in comparison to the exact tests? IOW,
> how much of a problem is it to potentially do a bbox check twice?

Very very cheap. The geometry object usually has a bbox already instantiated and stored along with the actual
coordinates.The exceptions are objects (points, two-vertex lines) that are basically their own boxes anyways. 

P

>
> Greetings,
>
> Andres Freund



pgsql-hackers by date:

Previous
From: Andres Freund
Date:
Subject: Re: Changing SQL Inlining Behaviour (or...?)
Next
From: Alvaro Herrera
Date:
Subject: Re: problems with foreign keys on partitioned tables