Re: [PATCH v2 2/2] alter: zap space_vtab::commit_alter

[Konstantin Osipov <kostja@tarantool.org>]

* Vladimir Davydov <vdavydov.dev@gmail.com> [18/04/06 17:25]:
> On Fri, Apr 06, 2018 at 05:10:01PM +0300, Konstantin Osipov wrote:
> > * Vladimir Davydov <vdavydov.dev@gmail.com> [18/04/06 16:20]:
> > 
> > > space_vtab::commit_alter is implemented only by memtx, which uses it
> > > to set bsize for a new space. However, it isn't necessary to use
> > > commit_alter for this - instead we can set bsize in prepare_alter and
> > > reset it in drop_primary_key, along with memtx_space::replace. Let's
> > > do it and zap space_vtab::commit_alter altogether, because the callback
> > > is confusing: judging by its name it should be called after WAL write,
> > > but it is called before.
> > >  void
> > >  DropIndex::alter(struct alter_space *alter)
> > >  {
> > > -	space_drop_primary_key(alter->new_space);
> > > +	if (old_index_def->iid == 0)
> > > +		space_drop_primary_key(alter->new_space);
> > >  }
> > 
> > I keep wondering why you ditched a nice comment.
> > If you think it was bad, please write a better one.
> 
> This comment is only pertinent to memtx so I just moved it to
> memtx_space_drop_primary_key.

> > > -	/*
> > > -	 * If it's not the primary key, nothing to do --
> > > -	 * the dropped index didn't exist in the new space
> > > -	 * definition, so does not exist in the created space.
> > > -	 */

What about this hunk?

Anyway, it's not self-explanatory. Why aren't we doing anything
here for the secondary index and have to take an extra step for
primary? 

This is not obvious.

> > a new good comment.

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Konstantin Osipov, Moscow, Russia, +7 903 626 22 32
http://tarantool.io - www.twitter.com/kostja_osipov