Horton

Re: ALTER TABLE ADD COLUMN fast default

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
Cc: David Rowley <david.rowley@2ndquadrant.com>, Thomas Munro <thomas.munro@enterprisedb.com>, Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2018-03-29T23:40:29Z
Lists: pgsql-hackers 
Hi,

On 2018-03-30 10:08:54 +1030, Andrew Dunstan wrote:
> On Fri, Mar 30, 2018 at 5:00 AM, Andres Freund <andres@anarazel.de> wrote:
> > this'll trigger one slot_getsomeattrs(slot, 2) call from within qual
> > evaluation, and then a slot_getsomeattrs(slot, 4) from within the
> > projection code.  If you then imagine a tuple where only the first
> > column exists physically, we'd copy b twice, because attno is only going
> > to be one 1.  I think we might just want to check tts nvalid in
> > getmissingattrs?

> OK. so add something like this to the top of slot_getmissingattrs()?
> 
>     startAttNum = Max(startAttNum, slot->tts_nvalid);

Yea, I think that should do the trick.

Greetings,

Andres Freund

Commits

  1. Clean up treatment of missing default and CHECK-constraint records.

  2. Fast ALTER TABLE ADD COLUMN with a non-NULL default

  3. Fix application of identity values in some cases