[tarantool-patches] Re: [PATCH 0/8] Get rid of Vinyl's mem_format_with_colmask

[Konstantin Osipov <kostja@tarantool.org>]

* Vladimir Davydov <vdavydov.dev@gmail.com> [18/10/15 10:15]:
> There are two formats for memory statements in Vinyl, vy_lsm::mem_format
> and vy_lsm::mem_format_with_colmask. The only difference between them is
> that the latter allows to store column mask inside tuples. It is used to
> optimize out tautological updates in the write iterator. Turns out that
> we can easily do without it as this patch set demonstrates.
> 
> I've always wanted to drop this format because I hate the very idea of
> tuple_extra (that's why I dropped upsert format a while ago as well).
> However, the reason why I'm doing this now is that it is the only thing
> why we need tuple_format_dup. Currently, tuple_format_dup is basically a
> memcpy, but once JSON indexes are introduced it's going to become much
> more complex than just that so we'd better drop it now.

First, I disagree with both premises:

- we will need tuple_extra anyway, for capped collections
- you can't guarantee that a pretty basic method of an object such as creating 
  a deep copy will never be used in the future, so there is no
  much point in attacking it now.

Yet I am happy to look at the patch trimming the code on the edges so a review
follows.

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