Re: FETCH FIRST clause PERCENT option

From: Vik Fearing <vik(dot)fearing(at)2ndquadrant(dot)com>
To: Surafel Temesgen <surafel3000(at)gmail(dot)com>, Mark Dilger <hornschnorter(at)gmail(dot)com>
Cc: Andres Freund <andres(at)anarazel(dot)de>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>
Subject: Re: FETCH FIRST clause PERCENT option
Date: 2018-11-25 10:24:03
Message-ID: 44e18a0f-ea74-e24f-f8c7-5d73c9f3282d@2ndquadrant.com
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On 25/11/2018 10:00, Surafel Temesgen wrote:
>
>
>
>
> I messed around with your changes to the grammar and it seems you don't
> need to add PERCENT as a reserved keyword.  Moving this to the
> unreserved
> keyword section does not cause any shift/reduce errors, and the
> regression
> tests still pass.  Relative to your patch v4, these changes help:
>
>
> In sql standard PERCENT list as reserved world so i don't think it is a
> thing that can change by me.

Yes it absolutely is. In PostgreSQL we only make words as reserved as
they need to be, and PERCENT doesn't need to be reserved at all.

Also, this query returns 210 rows instead of the expected 208:

select *
from generate_series(1, 1000)
fetch first 20.8 percent rows only

As for the design, I think you should put some serious consideration
into Andrew Gierth's approach. I would rather see something like that.
--
Vik Fearing +33 6 46 75 15 36
http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support

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