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From: Vladimir Davydov <vdavydov.dev@gmail.com>
To: Alexander Turenko <alexander.turenko@tarantool.org>
Cc: Kirill Shcherbatov <kshcherbatov@tarantool.org>,
	tarantool-patches@freelists.org
Subject: Re: [tarantool-patches] Re: [PATCH v2 2/2] lua: add key_def lua module
Date: Thu, 4 Apr 2019 17:36:56 +0300	[thread overview]
Message-ID: <20190404143655.ymzuaihqcxzjjf3j@esperanza> (raw)
In-Reply-To: <20190404114622.cunxe3zhnaux5gd7@tkn_work_nb>

On Thu, Apr 04, 2019 at 02:46:22PM +0300, Alexander Turenko wrote:
> > > >> Probably, we should reuse tuple_validate() for checking a tuple against
> > > >> a key_def so as not to implement the same code again.
> > > 
> > > Unfortunately tuple_validate() is designed for format validation while we don't
> > > have format here and I don't like create it for validation event in case of error.
> > 
> > Creating a format on each call to 'compare' is prohibitive from
> > performance pov, you're right. However, we could attach a format to
> > Lua's key_def object. This would also speed up comparisons, as tuples
> 
> So this module will not more be relatively simple layer that exposes
> box/key_def into Lua and this again suggests me that the name key_def
> maybe is not good choice.
> 
> > created for this format would have fieldmap.
> 
> Note: It will speed up comparisons only in case when a user give a lua

Yeah, right. So speeding up comparisons isn't an iron-clad argument
for attaching a format to Lua key_def object. May be not worth the
complexity it will introduce.

> table as input, not when it give a tuple. However if a user give a tuple
> it seems that it is in (s)he responsibility to think about the format.
> 
> And, while we're here, maybe it worth to provide a function like
> box.tuple.new(), but with key_def instance as an argument to allow a
> user to create tuples with necessary formats (to speed up comparisons
> and other fields accesses)?

No, I don't think so: the API wouldn't be generic enough, because one
might want to compare the same tuple using different key definitions.

> 
> > However, what I don't like is that in case a tuple is created from a Lua
> > table, you'll have to access all fields twice - on validation and
> > comparison - which is costly without a fieldmap. One more argument for
> > attaching a format to Lua's key_def object.
> 
> I think we can add *_unchecked() function variants like in
> msgpack/msgpackffi if the peformance will be really a problem and
> someone will request for them.

I don't think that _unchecked (i.e. crash on malformed input) is a good
idea, especially in this case.

  reply	other threads:[~2019-04-04 14:36 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-27 14:29 [tarantool-patches] [PATCH v2 0/2] " Kirill Shcherbatov
2019-03-27 14:29 ` [tarantool-patches] [PATCH v2 1/2] lua: add luaT_tuple_new() Kirill Shcherbatov
2019-03-28  9:01   ` [tarantool-patches] " Konstantin Osipov
2019-03-28  9:18     ` Alexander Turenko
2019-04-03 18:01   ` [tarantool-patches] " Vladimir Davydov
2019-04-04  2:51     ` Alexander Turenko
2019-04-04  8:14       ` Vladimir Davydov
2019-03-27 14:29 ` [tarantool-patches] [PATCH v2 2/2] lua: add key_def lua module Kirill Shcherbatov
2019-03-28  2:01   ` Alexander Turenko
2019-03-28  7:38     ` [tarantool-patches] " Kirill Shcherbatov
2019-03-28  8:41     ` Kirill Shcherbatov
     [not found]       ` <6d915212-e80f-4a6d-d884-b838bf25f8a7@tarantool.org>
2019-03-28 11:22         ` Alexander Turenko
2019-04-03 11:10           ` Vladimir Davydov
2019-04-03 11:46             ` Alexander Turenko
2019-04-03 12:01               ` Vladimir Davydov
2019-04-03 13:26                 ` Alexander Turenko
2019-04-04  5:07             ` Alexander Turenko
2019-04-04  8:04               ` Kirill Shcherbatov
2019-04-04  9:05                 ` Vladimir Davydov
2019-04-04 11:46                   ` Alexander Turenko
2019-04-04 14:36                     ` Vladimir Davydov [this message]
2019-04-04  8:38               ` Vladimir Davydov
2019-04-04 11:17                 ` Alexander Turenko
2019-04-04 12:00                   ` Alexander Turenko
2019-04-04 14:42                     ` Vladimir Davydov

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