| From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
| Cc: | Greg Stark <stark(at)mit(dot)edu>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Josh Berkus <josh(at)agliodbs(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: First-draft release notes for next week's releases |
| Date: | 2014-03-17 23:55:26 |
| Message-ID: | 20140317235526.GT16438@awork2.anarazel.de |
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| Thread: | |
| Lists: | pgsql-hackers |
On 2014-03-17 20:51:31 -0300, Alvaro Herrera wrote:
> > I think the best way to really cleanup a table is to use something like:
> > ALTER TABLE rew ALTER COLUMN data TYPE text USING (data);
> > where text is the previous type of the column. That should trigger a
> > full table rewrite, without any finesse about tracking ctid chains.
>
> Isn't this what VACUUM FULL does?
No, it uses rewriteheap.c via cluster.c, which tries to preserve
visibility information. There's tracking/mapping of t_ctid... I am not
entirely sure how much it preserves, but I am not really hopeful.
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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