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Sylvain Lebresne commented on CASSANDRA-7423:
---------------------------------------------
Very minor nit (haven't looked at the patch) but can you add an entry to the
CQL doc changelog and include a link to the ticket in that entry (I know we
used to not do the latter but lets try to take the habit to as it was suggested
to me it would be useful to some people and that's easy to do).
> Allow updating individual subfields of UDT
> ------------------------------------------
>
> Key: CASSANDRA-7423
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7423
> Project: Cassandra
> Issue Type: Improvement
> Components: CQL
> Reporter: Tupshin Harper
> Assignee: Tyler Hobbs
> Labels: client-impacting, cql, docs-impacting
> Fix For: 3.x
>
>
> Since user defined types were implemented in CASSANDRA-5590 as blobs (you
> have to rewrite the entire type in order to make any modifications), they
> can't be safely used without LWT for any operation that wants to modify a
> subset of the UDT's fields by any client process that is not authoritative
> for the entire blob.
> When trying to use UDTs to model complex records (particularly with nesting),
> this is not an exceptional circumstance, this is the totally expected normal
> situation.
> The use of UDTs for anything non-trivial is harmful to either performance or
> consistency or both.
> edit: to clarify, i believe that most potential uses of UDTs should be
> considered anti-patterns until/unless we have field-level r/w access to
> individual elements of the UDT, with individual timestamps and standard LWW
> semantics
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