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https://issues.apache.org/jira/browse/CASSANDRA-12127?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15378429#comment-15378429
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Tyler Hobbs commented on CASSANDRA-12127:
-----------------------------------------
I have not looked through the complete patches, but one thing that worries me
is changing the behavior of {{ReversedType::compareCustom()}}. The new
behavior is certain the correct behavior, but I'm not sure how this change
might interact with existing, incorrectly ordered data on disk. It would be
good to run some tests to determine what happens and how we can mitigate any
problems before merging this.
> Queries with empty ByteBuffer values in clustering column restrictions fail
> for non-composite compact tables
> ------------------------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-12127
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12127
> Project: Cassandra
> Issue Type: Bug
> Components: CQL
> Reporter: Benjamin Lerer
> Assignee: Benjamin Lerer
> Fix For: 2.1.x, 2.2.x, 3.0.x, 3.x
>
> Attachments: 12127.txt
>
>
> For the following table:
> {code}
> CREATE TABLE myTable (pk int,
> c blob,
> value int,
> PRIMARY KEY (pk, c)) WITH COMPACT STORAGE;
> INSERT INTO myTable (pk, c, value) VALUES (1, textAsBlob('1'), 1);
> INSERT INTO myTable (pk, c, value) VALUES (1, textAsBlob('2'), 2);
> {code}
> The query: {{SELECT * FROM myTable WHERE pk = 1 AND c > textAsBlob('');}}
> Will result in the following Exception:
> {code}
> java.lang.ClassCastException:
> org.apache.cassandra.db.composites.Composites$EmptyComposite cannot be cast
> to org.apache.cassandra.db.composites.CellName
> at
> org.apache.cassandra.db.composites.AbstractCellNameType.cellFromByteBuffer(AbstractCellNameType.java:188)
> at
> org.apache.cassandra.db.composites.AbstractSimpleCellNameType.makeCellName(AbstractSimpleCellNameType.java:125)
> at
> org.apache.cassandra.db.composites.AbstractCellNameType.makeCellName(AbstractCellNameType.java:254)
> at
> org.apache.cassandra.cql3.statements.SelectStatement.makeExclusiveSliceBound(SelectStatement.java:1206)
> at
> org.apache.cassandra.cql3.statements.SelectStatement.applySliceRestriction(SelectStatement.java:1214)
> at
> org.apache.cassandra.cql3.statements.SelectStatement.processColumnFamily(SelectStatement.java:1292)
> at
> org.apache.cassandra.cql3.statements.SelectStatement.process(SelectStatement.java:1259)
> at
> org.apache.cassandra.cql3.statements.SelectStatement.processResults(SelectStatement.java:299)
> [...]
> {code}
> The query: {{SELECT * FROM myTable WHERE pk = 1 AND c < textAsBlob('');}}
> Will return 2 rows instead of 0.
> The query: {{SELECT * FROM myTable WHERE pk = 1 AND c = textAsBlob('');}}
> {code}
> java.lang.AssertionError
> at
> org.apache.cassandra.db.composites.SimpleDenseCellNameType.create(SimpleDenseCellNameType.java:60)
> at
> org.apache.cassandra.cql3.statements.SelectStatement.addSelectedColumns(SelectStatement.java:853)
> at
> org.apache.cassandra.cql3.statements.SelectStatement.getRequestedColumns(SelectStatement.java:846)
> at
> org.apache.cassandra.cql3.statements.SelectStatement.makeFilter(SelectStatement.java:583)
> at
> org.apache.cassandra.cql3.statements.SelectStatement.getSliceCommands(SelectStatement.java:383)
> at
> org.apache.cassandra.cql3.statements.SelectStatement.getPageableCommand(SelectStatement.java:253)
> [...]
> {code}
> I checked 2.0 and {{SELECT * FROM myTable WHERE pk = 1 AND c >
> textAsBlob('');}} works properly but {{SELECT * FROM myTable WHERE pk = 1 AND
> c < textAsBlob('');}} return the same wrong results than in 2.1.
> The {{SELECT * FROM myTable WHERE pk = 1 AND c = textAsBlob('');}} is
> rejected if a clear error message: {{Invalid empty value for clustering
> column of COMPACT TABLE}}.
> As it is not possible to insert an empty ByteBuffer value within the
> clustering column of a non-composite compact tables those queries do not
> have a lot of meaning. {{SELECT * FROM myTable WHERE pk = 1 AND c <
> textAsBlob('');}} and {{SELECT * FROM myTable WHERE pk = 1 AND c =
> textAsBlob('');}} will return nothing
> and {{SELECT * FROM myTable WHERE pk = 1 AND c > textAsBlob('');}} will
> return the entire partition (pk = 1).
> In my opinion those queries should probably all be rejected as it seems that
> the fact that {{SELECT * FROM myTable WHERE pk = 1 AND c > textAsBlob('');}}
> was accepted in {{2.0}} was due to a bug.
> I am of course open to discussion.
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