Horton

Re: ALTER TABLE ADD COLUMN fast default

David Rowley <david.rowley@2ndquadrant.com>

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From: David Rowley <david.rowley@2ndquadrant.com>
To: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
Cc: Andres Freund <andres@anarazel.de>, Thomas Munro <thomas.munro@enterprisedb.com>, Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2018-03-08T13:11:33Z
Lists: pgsql-hackers 
On 8 March 2018 at 18:40, Andrew Dunstan <andrew.dunstan@2ndquadrant.com> wrote:
>  select * from t;
>  fastdef tps = 107.145811
>  master  tps = 150.207957
>
> "select * from t" used to be about a wash, but with this patch it's
> got worse. The last two queries were worse and are now better, so
> that's a win.

How does it compare to master if you drop a column out the table?
Physical tlists will be disabled in that case too. I imagine the
performance of master will drop much lower than the all columns
missing case.



-- 
 David Rowley                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

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