Yes, you will have it like that :) Thank you for this idea. Great example
of cooperation over diverse domains.
On Fri, Apr 11, 2025 at 12:29 AM David Capwell <dcapw...@apple.com> wrote:
> I am biased but I do prefer
>
> val3 text CHECK NOT NULL AND JSON AND LENGTH() < 1024
>
> Here is a similar accord CQL
>
> BEGIN TRANSACTION
> LET a = (…);
> IF a IS NOT NULL
> AND a.b IS NOT NULL
> AND a.c IS NULL; THEN
> — profit
> END IF
> COMMIT TRANSACTION
>
> On Apr 10, 2025, at 8:46 AM, Yifan Cai <yc25c...@gmail.com> wrote:
>
> Re: reserved keywords, “check” is currently not, and I don’t think it
> needs to be a reserved keyword with the proposal.
>
> ------------------------------
> *From:* C. Scott Andreas <sc...@paradoxica.net>
> *Sent:* Thursday, April 10, 2025 7:59:35 AM
> *To:* dev@cassandra.apache.org <dev@cassandra.apache.org>
> *Cc:* dev@cassandra.apache.org <dev@cassandra.apache.org>
> *Subject:* Re: Constraint's "not null" alignment with transactions and
> their simplification
>
> If the proposal does not introduce “check” as a reserved keyword that
> would require quoting in existing DDL/DML, this concern doesn’t apply and
> the email below can be ignored. This might be the case if “CHECK NOT NULL”
> is the full token introduced rather than “CHECK” separately from
> constraints that are checked.
>
> If “check” is introduced as a standalone reserved keyword: my primary
> feedback is on the introduction of reserved words in the CQL grammar that
> may affect compatibility of existing schemas.
>
> In the Cassandra 3.x series, several new CQL reserved words were added
> (more than necessary) and subsequently backed out, because it required
> users to begin quoting schemas and introduced incompatibility between 3.x
> and 4.x for queries and DDL that “just worked” before.
>
> The word “check” is used in many domains (test/evaluation engineering,
> finance, business processes, etc) and is likely to be used in user schemas.
> If the proposal introduces this as a reserved word that would require it to
> be quoted if used in table or column names, this will create
> incompatibility for existing user queries on upgrade.
>
> Otherwise, ignore me. :)
>
> Thanks,
>
> – Scott
>
> –––
> Mobile
>
> On Apr 10, 2025, at 7:47 AM, Jon Haddad <j...@rustyrazorblade.com> wrote:
>
>
> This looks like a really nice improvement to me.
>
>
> On Thu, Apr 10, 2025 at 7:27 AM Štefan Miklošovič <smikloso...@apache.org>
> wrote:
>
> Recently, David Capwell was commenting on constraints in one of Slack
> threads (1) in dev channel and he suggested that the current form of "not
> null" constraint we have right now in place, e.g like this
>
> create table ks.tb (id int primary key, val int check not_null(val));
>
> could be instead of that form used like this:
>
> create table ks.tb (id int primary key, val int check not null);
>
> That is - without the name of a column in the constraint's argument. The
> reasoning behind that was that it is not only easier to read but there is
> also this concept in transactions (cep-15) where there is also "not null"
> used in some fashion and it would be nice if this was aligned so a user
> does not encounter two usages of "not null"-s which are written down
> differently, syntax-wise.
>
> Could the usage of "not null" in transactions be confirmed?
>
> This rather innocent suggestion brought an idea to us that constraints
> could be quite simplified when it comes to their syntax, consider this:
>
> val int check not_null(val)
> val text check json(val)
> val text check lenght(val) < 1000
>
> to be used like this:
>
> val int check not null
> val text check json
> val text check length() < 1000
>
> more involved checks like this:
>
> val text check not_null(val) and json(val) and length(val) < 1000
>
> might be just simplified to:
>
> val text check not null and json and length() < 1000
>
> It almost reads like plain English. Isn't this just easier for an eye?
>
> The reason we kept the column names in constraint definitions is that,
> frankly speaking, we just did not know any better at the time it was about
> to be implemented. It is a little bit more tricky to be able to use it
> without column names because in Parser.g / Antlr we just bound the grammar
> around constraints to a column name directly there. When column names are
> not going to be there anymore, we need to bind it later in the code behind
> the parser in server code. It is doable, it was just about being a little
> bit more involved there.
>
> Also, one reason to keep the name of a column was that we might specify
> different columns in a constraint from a column that is defined on to have
> cross-column constraints but we abandoned this idea altogether for other
> reasons which rendered the occurrence of a column name in a constraint
> definition redundant.
>
> To have some overview of what would be possible to do with this proposal:
>
> val3 text CHECK SOMECONSTRAINT('a');
> val3 text CHECK JSON;
> val3 text CHECK SOMECONSTRAINT('a') > 1;
> val3 text CHECK SOMECONSTRAINT('a', 'b', 'c') > 1;
> val3 text CHECK JSON AND LENGTH() < 600;
> afternoon time CHECK afternoon >= '12:00:00' AND afternoon =< '23:59:59';
> val3 text CHECK NOT NULL AND JSON AND LENGTH() < 1024
>
> In addition to the specification of constraints without columns, what
> would be possible to do is to also specify arguments to constraints. It is
> currently not possible and there is no constraint which would accept
> arguments to its function but I think that to be as flexible as possible
> and prepare for the future, we might implement it as well.
>
> Constraints in their current form are already usable however I just think
> that if we do not simplify, align and extend the syntax right now, before
> it is baked in in a release, then we will never do it as it will be quite
> tricky to extend this without breaking it and maintaining two grammars at
> the same time would be very complex if not flat out impossible.
>
> Are you open to the simplification of constraint definitions as suggested
> and what is your feedback about that? I already have a working POC which
> just needs to be polished and tests fixed to accommodate the new approach.
>
> Regards
>
> (1) https://the-asf.slack.com/archives/CK23JSY2K/p1742409054164389
>
>
>
