Re: locks in CREATE TRIGGER, ADD FK

On Wed, Mar 23, 2005 at 10:42:01AM +0800, Christopher Kings-Lynne wrote:
> >>If you want to be my friend forever, then fix CLUSTER so that it uses 
> >>sharerowexclusive as well :D
> >
> >I don't think it's as easy as that, because you have to move tuples
> >around in the cluster operation.  Same sort of issue as vacuum full I 
> >would suggest.
> 
> Cluster doesn't move rows...
> 
> I didn't say it was easy.  It would involve changing how cluster works. 
>  It would keep the old table around while building the new, then grab 
> an exclusive lock to swap the two.

Huh, cluster already does that.

I don't remember what the rationale was for locking the table, leaving
even simple SELECTs out.  (In fact, IIRC the decision wasn't made by me,
and it wasn't discussed at all.)

-- 
Alvaro Herrera (<alvherre[@]dcc.uchile.cl>)
"I would rather have GNU than GNOT."  (ccchips, lwn.net/Articles/37595/)