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https://issues.apache.org/jira/browse/CASSANDRA-6783?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sylvain Lebresne updated CASSANDRA-6783:
----------------------------------------
Attachment: (was: 6783-2.txt)
> Collections should have a proper compare() method for UDT
> ---------------------------------------------------------
>
> Key: CASSANDRA-6783
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6783
> Project: Cassandra
> Issue Type: Bug
> Reporter: Sylvain Lebresne
> Assignee: Sylvain Lebresne
> Fix For: 2.1 beta2
>
> Attachments: 6783.txt
>
>
> So far, ListType, SetType and MapType don't have a proper implementation of
> compare() (they throw UnsupportedOperationException) because we haven't need
> one since as far as the cell comparator is concenred, only parts of a
> collection ends up in the comparator and need to be compared, but the full
> collection itself does not.
> But with UDT can nest a collection and that sometimes require to be able to
> compare them. Typically, I pushed a dtest
> [here|https://github.com/riptano/cassandra-dtest/commit/290e9496d1b2c45158c7d7f5487d09ba48897a7f]
> that ends up throwing:
> {noformat}
> java.lang.UnsupportedOperationException: CollectionType should not be use
> directly as a comparator
> at
> org.apache.cassandra.db.marshal.CollectionType.compare(CollectionType.java:72)
> ~[main/:na]
> at
> org.apache.cassandra.db.marshal.CollectionType.compare(CollectionType.java:37)
> ~[main/:na]
> at
> org.apache.cassandra.db.marshal.AbstractType.compareCollectionMembers(AbstractType.java:174)
> ~[main/:na]
> at
> org.apache.cassandra.db.marshal.AbstractCompositeType.compare(AbstractCompositeType.java:101)
> ~[main/:na]
> at
> org.apache.cassandra.db.marshal.AbstractCompositeType.compare(AbstractCompositeType.java:35)
> ~[main/:na]
> at java.util.TreeMap.compare(TreeMap.java:1188) ~[na:1.7.0_45]
> at java.util.TreeMap.put(TreeMap.java:531) ~[na:1.7.0_45]
> at java.util.TreeSet.add(TreeSet.java:255) ~[na:1.7.0_45]
> at org.apache.cassandra.cql3.Sets$DelayedValue.bind(Sets.java:205)
> ~[main/:na]
> at org.apache.cassandra.cql3.Sets$Literal.prepare(Sets.java:91)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.UserTypes$Literal.prepare(UserTypes.java:60)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.Operation$SetElement.prepare(Operation.java:221)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.UpdateStatement$ParsedUpdate.prepareInternal(UpdateStatement.java:201)
> ~[main/:na]
> ...
> {noformat}
> Note that this stack doesn't involve cell name comparison at all, it's just
> that CQL3 sometimes uses a SortedSet underneath to deal with set literals
> (since internal sets are sorted by their value), and so when a set contains
> UDT that has set themselves, we need the collection comparison. That being
> said, for some cases like having a UDT as a map key, we do would need
> collections to be comparable for the purpose of cell name comparison.
> Attaching relatively simple patch. The patch is a bit bigger than it should
> be because while adding the 3 simple compare() method, I realized that we had
> methods to read a short length (2 unsigned short) from a ByteBuffer
> duplicated all over the place and that it was time to consolidate that in
> ByteBufferUtil where it should have been from day one (thus removing the
> duplication). I can separate that trivial refactor in a separate patch if we
> really need to, but really, the new stuff is the compare() method
> implementation in ListType, SetType and MapType and the rest is a bit of
> trivial cleanup.
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