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https://issues.apache.org/jira/browse/CASSANDRA-20982?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18044134#comment-18044134
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Sam Tunnicliffe commented on CASSANDRA-20982:
---------------------------------------------
The complication obviously is that this changes the behaviour of some ALTER
TABLE statements and while this behaviour change in itself may not be
problematic for users the reasons [~brandon.williams] mentioned, from a TCM
perspective it's a bit more involved.
DDL statements are recorded as operations in the metadata log and may be
replayed during node startup or when a peer falls behind and has to catch up.
If the implementation changes so that a stmt is permitted in version X and
denied in X+1, that would very likely cause problems. Once an operation is
committed to the log, it must be executable by any node in the cluster.
Committing this change to trunk now would only be an issue for operators
running pre-release versions with TCM. Any upgrade from 5.0 (or earlier) to
such a version would be fine.
If this change (or something similar) were to land in later version like 6.0.1,
there are a couple of issues to negotiate:
* An existing cluster running 6.0.0 may already have stmts committed to its
log which will become un-replayable
* During the 6.0.0 -> 6.0.1 upgrade the cluster is in a mixed state where some
nodes will allow certain stmts which other nodes will not
That would probably require moving this specific validation around type
compatibility out from {{AlterTable$AddColumns.apply}} and adding an element of
version checking to it.
Like I said, I don't think this is necessary to commit this to trunk now, but
here's how it could be handled if something like this landed in a later
version:
[https://github.com/beobal/cassandra/commit/a01af6dc5607066a98cfdb69f5b00fcacf4bf548]
> BytesType should only be compatible with simple scalar types
> ------------------------------------------------------------
>
> Key: CASSANDRA-20982
> URL: https://issues.apache.org/jira/browse/CASSANDRA-20982
> Project: Apache Cassandra
> Issue Type: Bug
> Components: Cluster/Schema
> Reporter: Brandon Williams
> Assignee: MikoĊaj
> Priority: Normal
> Fix For: 4.0.x, 4.1.x, 5.0.x, 5.x
>
> Time Spent: 2h 20m
> Remaining Estimate: 0h
>
> Discovered while backporting CASSANDRA-18760, see
> https://github.com/datastax/cassandra/commit/b5f7d239ce92db7d9c5f79c69cad0caea67fcb23
> Basically, things like
> https://github.com/apache/cassandra/blob/trunk/test/unit/org/apache/cassandra/cql3/validation/operations/AlterTest.java#L71
> shouldn't be allowed to pass, because converting a frozen collection to
> bytes allows reading the raw bytes, which is nonsensical.
> This was found because the AbstractTypeTest is beefed up
> [here|https://github.com/datastax/cassandra/blob/main/test/unit/org/apache/cassandra/db/marshal/AbstractTypeTest.java]
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