From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Thomas Munro <munro(at)ip9(dot)org> |
Cc: | "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: NEXT VALUE FOR <sequence> |
Date: | 2014-10-02 23:18:48 |
Message-ID: | 6116.1412291928@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
Thomas Munro <munro(at)ip9(dot)org> writes:
> On 2 October 2014 14:48, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Have you checked the archives about this? My recollection is that one
>> reason it's not in there (aside from having to reserve "NEXT") is that
>> the standard-mandated semantics are not the same as nextval().
> Right, I found the problem: "If there are multiple instances of <next value
> expression>s specifying the same sequence generator within a single
> SQL-statement, all those instances return the same value for a
> given row processed by that SQL-statement." This was discussed in a thread
> from 2002 [1].
Wow, it was that far back? No wonder I didn't remember the details.
> I suppose one approach would be to use command
> IDs as the scope.
The spec clearly says one value per row, not one per statement; so
command ID is very definitely not the right thing.
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Joe Conway | 2014-10-02 23:38:24 | Re: DDL Damage Assessment |
Previous Message | Marti Raudsepp | 2014-10-02 23:15:27 | Re: CREATE IF NOT EXISTS INDEX |