Re: Reduce lock levels others reloptions in ALTER TABLE

On 1 March 2016 at 19:00, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Mon, Feb 29, 2016 at 12:58 PM, Fabrízio de Royes Mello
> <fabriziomello(at)gmail(dot)com> wrote:
> > Some time ago we added [1] the infrastructure to allow different lock
> levels
> > for relation options.
> >
> > So per discussion [2] the attached patch reduce lock levels down to
> > ShareUpdateExclusiveLock for:
> > - fastupdate
> > - fillfactor
> > - gin_pending_list_limit
> > - seq_page_cost
> > - random_page_cost
> > - n_distinct
> > - n_distinct_inherited
> > - buffering
>
> I am of the opinion that there needs to be comments or a README or
> some kind of documentation somewhere indicating the rationale for the
> lock levels we choose here. Just changing it without analyzing why a
> certain level is sufficient for safety and no higher than necessary
> seems poor. And the reasoning should be documented for future
> readers.
>

+1

The patch altered tests for fillfactor, so I extracted just that parameter
from the patch for commit, after adding comments and docs.

Fabrízio, you've been around long enough to know that patches need docs and
tests. And as Robert says, comments that show you've done the analysis to
show you know the patch is safe.

Some parts of this patch could be resubmitted in a later CF with some time
and attention spent on it, but it isn't in a good enough state for last CF.

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