Andreas Mager created CASSANDRA-19349:
-----------------------------------------

             Summary: Timeuuid compare is broken
                 Key: CASSANDRA-19349
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-19349
             Project: Cassandra
          Issue Type: Bug
            Reporter: Andreas Mager


 

I have stumbled over a wired problem on my pc.

{{When i turn on my wifi interface, then some of my integration test are 
failing.}}

{{The mac part(lsb) of the timeuuids become changed in our Uuid 
implementation.}}

{{ These uuids are used for the cassandra insertions and queries.}}

 

{{TestSetup with "broken" Uuids:}}
{code:java}
CREATE TABLE object_comment (
    object timeuuid,
    comment timeuuid,
    value blob,
    PRIMARY KEY (object, comment)
)

INSERT INTO object_comment (object, comment , value) VALUES 
(95278adc-c03f-11ee-ab43-bb35e932d536, cf9e6440-c01e-11ee-847b-34cff6b1be80, 
0x01);
INSERT INTO object_comment (object, comment , value) VALUES 
(95278adc-c03f-11ee-ab43-bb35e932d536, cf9f75b0-c01e-11ee-847b-34cff6b1be80, 
0x02);

// cf9f75b0-c01e-11ee-847b-34cff6b1be7f is lsb-1 and the same timestamp
SELECT * FROM object_comment where object = 
95278adc-c03f-11ee-ab43-bb35e932d536 AND comment <= 
cf9f75b0-c01e-11ee-847b-34cff6b1be7f; object                               | 
comment                              | value
--------------------------------------+--------------------------------------+-------
 95278adc-c03f-11ee-ab43-bb35e932d536 | cf9e6440-c01e-11ee-847b-34cff6b1be80 |  
0x01
 95278adc-c03f-11ee-ab43-bb35e932d536 | cf9f75b0-c01e-11ee-847b-34cff6b1be80 |  
0x02(2 rows)
 {code}
 

 

The second row must not be present. The Only row expected is : 
{code:java}
95278adc-c03f-11ee-ab43-bb35e932d536 | cf9e6440-c01e-11ee-847b-34cff6b1be80 |  
0x01{code}
 

I think i have found the cause of the issue.

The Methods `org.apache.cassandra.utils.TimeUUID#compareTo` and 
`org.apache.cassandra.db.marshal.TimeUUIDType#compareCustom` return different 
results.

Test pseudocode:
{code:java}
var id = UUID.fromString("cf9f75b0-c01e-11ee-847b-34cff6b1be80");
var idDecrementInLsb = UUID.fromString("cf9f75b0-c01e-11ee-847b-34cff6b1be7f");

// java.util.UUID#compareTo
assertThat(idDecrementInLsb.compareTo(id)).isEqualTo(-1);

var timeUuidDec = 
org.apache.cassandra.utils.TimeUUID.fromUuid(idDecrementInLsb);
var timeUuidId = org.apache.cassandra.utils.TimeUUID.fromUuid(id);

// org.apache.cassandra.utils.TimeUUID#compareTo
assertThat(timeUuidDec.compareTo(timeUuidId)).isEqualTo(-1);

// org.apache.cassandra.db.marshal.TimeUUIDType.compareCustom
assertThat(org.apache.cassandra.db.marshal.TimeUUIDType.compareCustom(idDecrementInLsb,
 id1)).isEqualTo(-1); // This fails
 {code}
 



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