Mailing-List: contact dev-help@cassandra.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@cassandra.apache.org
Received-SPF: pass (nike.apache.org: domain of povel.y@gmail.com designates
 74.125.82.44 as permitted sender)
References: 
 <CALdd-zjXtwT2hXDbPithL2oszM8HN80BG+0tnkSmzTo0Z02SOg@mail.gmail.com>
 <CAKkz8Q3+Cb-FmzCtwUcJHbZcwwtiGHqrN3yHB2WEvKLQZZYz1g@mail.gmail.com>
From: Pavel Yaskevich <povel.y@gmail.com>
In-Reply-To: 
 <CAKkz8Q3+Cb-FmzCtwUcJHbZcwwtiGHqrN3yHB2WEvKLQZZYz1g@mail.gmail.com>
Mime-Version: 1.0 (1.0)
Date: Wed, 26 Sep 2012 16:08:40 +0300
Message-ID: <3714302396387518439@unknownmsgid>
Subject: Re: Pushing Cassandra 1.2 back a month to November?
To: "dev@cassandra.apache.org" <dev@cassandra.apache.org>
Content-Type: text/plain; charset=ISO-8859-1

+1

26 sep 2012 kl. 15:56 skrev Sylvain Lebresne <sylvain@datastax.com>:

> +1
>
> On Tue, Sep 25, 2012 at 7:16 PM, Jonathan Ellis <jbellis@gmail.com> wrote:
>> We are more or less on track for the promised late October 1.2 release
>> [1] but I'm starting to think we should expand the scope of 1.2 a bit
>> to get cql3 and the corresponding binary protocol truly "right."
>>
>> Specifically,
>> 1) We'd like to move the consistency level setting from the CQL
>> language to the protocol level.
>> 2) The binary protocol only really has a Java implementation so far.
>> Having the time to flesh out the Python implementation would be a good
>> sanity check before we commit to protocol stability.
>>
>> Additionally,
>> 3) vnodes is a big change that could use more time to test.  I'd like
>> to avoid a repeat of the schema change mess from 1.1, where we did a
>> substantial rewrite that took six minor releases to get all the bugs
>> out of.
>>
>> Gory details on the CQL situation:
>>
>> Currently, in CQL3, you set the consistency level of an operation in
>> the language, eg 'SELECT * FROM foo USING CONSISTENCY QUORUM'.  It now
>> looks like this was a mistake, and that consistency should be set at
>> the protocol level, i.e. as a separate parameter along with the query.
>>
>> The reasoning is that the CL applies to the guarantee provided by the
>> operation being successful, not to the query itself.  Specifically,
>> having the CL being part of the language means that CL is opaque to
>> low level client libraries without themselves parsing the CQL, which
>> we want to avoid.  Thus,
>>
>>    - Those libraries can't implement automatic retries policy, where a query
>>      would be retried with a smaller CL.  (I'm aware that this is often a
>>      Bad Idea, but it does have legitimate uses and not having that available
>>      is seen as a regression from the Thrift api.)
>>    - We had to introduce CASSANDRA-4448 to allow the client to configure some
>>      form of default CL since the library can't handle that anymore, which is
>>      hackish.
>>    - Executing prepared statements with different CL requires preparing
>>      multiple statements.
>>    - CL only makes sense for BATCH operations as a whole, not the
>>      sub-statements within the batch. Currently CQL3 "fixes" that by
>>      validating the given CLs match, but it would be much more clear
>>      if the CL was on the protocol side.
>>
>> Moving the CL to the protocol level solves all of that but the problem
>> is, if we move the CL from the language to the protocol after 1.2,
>> that's a breaking change of CQL3, so we're talking CQL4.  Bad idea.
>>
>> [1] although later-than-planned freeze is a warning sign
>>
>> --
>> Jonathan Ellis
>> Project Chair, Apache Cassandra
>> co-founder of DataStax, the source for professional Cassandra support
>> http://www.datastax.com