[CASSANDRA-12127] Queries with empty ByteBuffer values in clustering column restrictions fail for non-composite compact tables

• Type: Bug
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 2.1.16, 2.2.8, 3.0.9
• Component/s: Legacy/CQL
• Severity: Normal
• Assignee: Benjamin Lerer
• Reporter: Benjamin Lerer

Authors

Benjamin Lerer

Reviewers

Jason Brown

• Created: 01/Jul/16 19:36
• Updated: 16/Apr/19 09:30
• Resolved: 16/Aug/16 13:54

Description

For the following table:

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);

The query: SELECT * FROM myTable WHERE pk = 1 AND c > textAsBlob('');

Will result in the following Exception:

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)
	[...]

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('');

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)
	[...]

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.

Issue Links

• relates to: CASSANDRA-14462 CAS temporarily broken on reversed tables after upgrading on 2.1.X or 2.2.X