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https://issues.apache.org/jira/browse/CASSANDRA-17047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17719855#comment-17719855
 ] 

Benjamin Lerer commented on CASSANDRA-17047:
--------------------------------------------

I will.

> Dropping a column can break queries until the schema is fully propagated 
> (TAKE 2)
> ---------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-17047
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-17047
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Cluster/Schema
>            Reporter: Benjamin Lerer
>            Assignee: Benjamin Lerer
>            Priority: Normal
>             Fix For: 3.0.x, 3.11.x, 4.0.x
>
>          Time Spent: 40m
>  Remaining Estimate: 0h
>
> With a table like:
> {code}
> CREATE TABLE ks.tbl (id int primary key, v1 int, v2 int, v3 int)
> {code}
> and we drop {{v2}}, we get this exception on the replicas which haven't seen 
> the schema change:
> {code}
> ERROR [SharedPool-Worker-1] node2 2020-06-24 09:49:08,107 
> AbstractLocalAwareExecutorService.java:169 - Uncaught exception on thread 
> Thread[SharedPool-Worker-1,5,node2]
> java.lang.IllegalStateException: [ColumnDefinition{name=v1, 
> type=org.apache.cassandra.db.marshal.Int32Type, kind=REGULAR, position=-1}, 
> ColumnDefinition{name=v2, type=org.apache.cassandra.db.marshal.Int32Type, 
> kind=REGULAR, position=-1}, ColumnDefinition{name=v3, 
> type=org.apache.cassandra.db.marshal.Int32Type, kind=REGULAR, position=-1}] 
> is not a subset of [v1 v3]
>       at 
> org.apache.cassandra.db.Columns$Serializer.encodeBitmap(Columns.java:546) 
> ~[main/:na]
>       at 
> org.apache.cassandra.db.Columns$Serializer.serializeSubset(Columns.java:478) 
> ~[main/:na]
>       at 
> org.apache.cassandra.db.rows.UnfilteredSerializer.serialize(UnfilteredSerializer.java:184)
>  ~[main/:na]
>       at 
> org.apache.cassandra.db.rows.UnfilteredSerializer.serialize(UnfilteredSerializer.java:114)
>  ~[main/:na]
>       at 
> org.apache.cassandra.db.rows.UnfilteredSerializer.serialize(UnfilteredSerializer.java:102)
>  ~[main/:na]
>       at 
> org.apache.cassandra.db.rows.UnfilteredRowIteratorSerializer.serialize(UnfilteredRowIteratorSerializer.java:132)
>  ~[main/:na]
>       at 
> org.apache.cassandra.db.rows.UnfilteredRowIteratorSerializer.serialize(UnfilteredRowIteratorSerializer.java:87)
>  ~[main/:na]
> ...
> {code}
> Note that it doesn't matter if we {{SELECT *}} or {{SELECT id, v1}}
> CASSANDRA-15899 tried to fix the problem when columns are dropped as well as 
> when columns are added. Unfortunately the fix introduced an issue and had to 
> be reverted in CASSANDRA-16735. 
> If the scenario for ADDED columns is tricky, the original scenario for 
> DROPPED columns can  be solved in a safe way at the {{ColumnFilter}} level. 
> By consequence, I think that we should at least solve that scenario.
> [~bdeggleston], [~samt], [~ifesdjeen] does my proposal makes sense to you?    



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