[jira] [Commented] (CASSANDRA-8480) Update of primary key should be possible

["Aleksey Yeschenko (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-8480?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14246642#comment-14246642 ] 

Aleksey Yeschenko commented on CASSANDRA-8480:
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The explanation for this is that primary key columns are internally parts of the cell name (or a partition's key), not a cell's value. And while you can update a cell's value, you can't update its name (and most certainly not a partition key).

Indeed, we kinda sorta maybe could implement it by deleting the old record entirely and writing a totally new one behind the scenes. I don't see a way to make it eventually consistent, however. Plus, it's at best debatable whether or not further hiding what's really going internally is a good thing.

If you need to update part of primary key, then in Cassandra view, you've modeled your schema incorrectly, and should redesign it.

> 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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