[jira] [Commented] (CASSANDRA-7423) make user defined types useful for non-trivial use cases

[" Brian Hess (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-7423?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14039352#comment-14039352 ] 

 Brian Hess commented on CASSANDRA-7423:
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I think what we want from UDTs is that the individual elements of the UDT are atomic pieces of data, just like columns of a CQL table.  They should be able to be retrieved on their own (which they are as implemented), as well as inserted/updated on their own (without having to get/modify/set the whole UDT).  The latter one is not supported as implemented and is a real issue.

One thing that comes out of them not being atomic pieces of data is that there is no safe way to update the UDT, but that is just one example.

> make user defined types useful for non-trivial use cases
> --------------------------------------------------------
>
>                 Key: CASSANDRA-7423
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7423
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: API, Core
>            Reporter: Tupshin Harper
>
> 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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