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https://issues.apache.org/jira/browse/CASSANDRA-4539?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Ellis updated CASSANDRA-4539:
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Reviewer: thepaul
> potential backwards incompatibility in native protocol
> ------------------------------------------------------
>
> Key: CASSANDRA-4539
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4539
> Project: Cassandra
> Issue Type: Improvement
> Components: API
> Affects Versions: 1.2.0 beta 1
> Reporter: paul cannon
> Assignee: Sylvain Lebresne
> Priority: Minor
> Labels: cql, native_protocol
> Fix For: 1.2.0 beta 1
>
> Attachments: 4539.txt
>
>
> In the text of the native_protocol.spec document, it explains the format for
> a notation called {{[option]}}, which should represent "{{a pair of
> <id><value>}}".
> In doing a first-draft implementation of the protocol for the python driver,
> though, I found that I had a misunderstanding. I read that section as saying
> that {{<value>}} was a {{[value]}}, and that it could have a length of 0
> (i.e., the {{[int]}} on the front of the {{[value]}} could be 0). However, it
> turns out that {{<value>}} might not be there at all, or might be *two*
> {{[value]}}'s, depending on the option id and message context.
> I'm not a fan of this, since
> * A protocol parsing library can't simply implement a single function to
> read in {{[option]}}'s, since the length of the value part is dependent on
> the message context
> * If we add a new native data type (a new option id which could be used
> inside a {{<col_spec_i>}} in a RESULT message), then older clients will not
> know how to read past the value part. Of course they won't know how to
> interpret the data or deserialize later rows of that unknown type - that's
> not the problem - the problem is that the older client should be able just to
> mark that column as unparseable and still handle the rest of the columns.
> Can we make {{<value>}} be a {{[value]}}, the contents of which can be
> re-interpreted as a {{[string]}}, an {{[option]}}, two {{[option]}}'s, or
> whatever?
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