+1 The vnode troubleshooting process has been rough, so I'm all for more testing there.
On Tue, Sep 25, 2012 at 12:16 PM, Jonathan Ellis <jbel...@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
