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https://issues.apache.org/jira/browse/CASSANDRA-4734?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13467766#comment-13467766
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Sylvain Lebresne commented on CASSANDRA-4734:
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bq. does that mean we should also remove set_cql_version
There's still prepare_cql_query that is shared by both versions and uses the
version set by set_cql_version. But I would agree that it's probably worth
duplicating that one too and removing set_cql_version.
bq. ave we already changed CQL3 enough that it's not worth the trouble?
Well, prior to this patch, the main syntax break was in CREATE statements (the
change to the map syntax). But this patch probably break way more code as any
non-trivial code will have code to adapt. That being said, backporting would
still probably help, the main problem being that I'm not sure how to properly
support both the new and old methods (i.e. the QueryProcessor in 1.1 would have
to support both the consistency in the language and in the protocol, which
seems messy).
> Move CQL3 consistency to protocol
> ---------------------------------
>
> Key: CASSANDRA-4734
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4734
> Project: Cassandra
> Issue Type: Task
> Components: API
> Reporter: Jonathan Ellis
> Assignee: Sylvain Lebresne
> Fix For: 1.2.0 beta 2
>
> Attachments: 0001-Move-consistency-level-to-the-protocol-level.txt,
> 0002-Remove-remains-of-4448.txt
>
>
> 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.
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