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Jason Kania commented on CASSANDRA-8480:
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Thanks for the response and explanation.
I am quite certain that with all your combined efforts to date you are looking
to make Cassandra as usable as possible. It is just a question of what you rule
out as possible versus documenting as performance impacting. I have worked in
the capacity of performance architect on several large scale production systems
and have had to balance user needs versus performance many times. My experience
is that when choosing between stopping what users can do versus having the big
flashing danger sign, the big flashing danger sign is usually what the end
users are looking for.
I would suggest that it might be worth polling users about which approach would
work versus falling back to core principles that may not be in the best
interests of wider product adoption.
> 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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