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https://issues.apache.org/jira/browse/CASSANDRA-8480?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14248388#comment-14248388
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Aleksey Yeschenko commented on CASSANDRA-8480:
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Don't get me wrong. We obviously want Cassandra to be as usable as possible,
and CQL as expressive as possible, too.
Yet, there are things that are fundamentally anti-Cassandra, and this request
is one of those things. One of the core principles of Cassandra is not
introducing implicit reads to the write path, thus having the write path have
consistent performance characteristics.
Another ticket similar to this one is CASSANDRA-6750. That one would also be
good to have. We recognize that. That said, being a distributed database with a
focus on scaling out, we have to restrict certain functionality that doesn't
fit the overall direction of the project :(
> Update of primary key should be possible
> ----------------------------------------
>
> Key: CASSANDRA-8480
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8480
> Project: Cassandra
> Issue Type: Improvement
> Components: API
> Reporter: Jason Kania
>
> While attempting to update a column in a row, I encountered the error
> PRIMARY KEY part thingy found in SET part
> The error is not helpful as it doesn't state why this is problem so I looked
> on google and encountered many, many entries from people who have experienced
> the issue including those with single column table who have to hack to work
> around this.
> After looking around further in the documentation, I discovered that it is
> not possible to update a primary key but I still have not found a good
> explanation. I suspect that that this is because it would change the indexing
> location of the record effectively requiring a delete followed by an insert.
> If the question is one of guaranteeing no update to a deleted row, a client
> will have the same issue.
> To me, this really should be handled behind the API because:
> 1) it is an expected capability in a database to update all columns and
> having these limitations only puts off potential users especially when they
> have to discover the limitation after the fact
> 2) being able to use a column in a WHERE clause requires it to be part of the
> primary key so what this limitation means is if you can update a column, you
> can't search for it, or if you can search on a column, you can't update it
> which leaves a serious gap in handling a wide number of use cases.
> 3) deleting and inserting a row with an updated primary key will mean sucking
> in all the data from the row up to the client and sending it all back down
> even when a single column in the primary key was all that was updated.
> Why not document the issue but make the interface more usable by supporting
> the operation?
> Jason
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