From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Michael Paquier <michael@paquier.xyz>
Cc: Justin Pryzby <pryzby@telsasoft.com>
Cc: pgsql-hackers@postgresql.org
Subject: Re: clean up docs for v12
Date: Mon, 22 Apr 2019 14:17:48 -0400
Message-ID: <20637.1555957068@sss.pgh.pa.us> (raw)
In-Reply-To: <20190422175547.cpjwgt2ghwyqy2cc@alap3.anarazel.de>
References: <20190422161955.GA17411@alvherre.pgsql>
<16490.1555950804@sss.pgh.pa.us>
<20190422164356.7d63s4bui3735r3q@alap3.anarazel.de>
<20190422165324.iyduznrdspcia7ja@alap3.anarazel.de>
<18604.1555954037@sss.pgh.pa.us>
<20190422175547.cpjwgt2ghwyqy2cc@alap3.anarazel.de>
Andres Freund <andres@anarazel.de> writes:
> On 2019-04-22 13:27:17 -0400, Tom Lane wrote:
>> I wonder
>> also if it wouldn't be smart to explicitly check that the "guaranteeing"
>> column is not attisdropped.
> Yea, that probably would be smart. I don't think there's an active
> problem, because we remove NOT NULL when deleting an attribute, but it
> seems good to be doubly sure / explain why that's safe:
> /* Remove any NOT NULL constraint the column may have */
> attStruct->attnotnull = false;
> I'm a bit unsure whether to make it an assert, elog(ERROR) or just not
> assume column presence?
I'd just make the code look like
/*
* If it's NOT NULL then it must be present in every tuple,
* unless there's a "missing" entry that could provide a non-null
* value for it. Out of paranoia, also check !attisdropped.
*/
if (att->attnotnull &&
!att->atthasmissing &&
!att->attisdropped)
guaranteed_column_number = attnum;
I don't think the extra check is so expensive as to be worth obsessing
over.
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, andres@anarazel.de, alvherre@2ndquadrant.com, michael@paquier.xyz, pryzby@telsasoft.com
Subject: Re: clean up docs for v12
In-Reply-To: <20637.1555957068@sss.pgh.pa.us>
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