[CASSANDRA-12060] Establish consistent distinction between non-existing partition and NULL value for LWTs on static columns

• Type: Bug
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 3.0.10, 3.10
• Component/s: Feature/Lightweight Transactions
• Labels: LWT
• Severity: Normal
• Assignee: Alex Petrov
• Reporter: Alex Petrov

Authors

Alex Petrov

Reviewers

Sylvain Lebresne

• Created: 22/Jun/16 15:49
• Updated: 25/Oct/19 13:11
• Resolved: 21/Sep/16 14:29

Description

When executing following CQL commands:

CREATE KEYSPACE test WITH replication = {'class': 'NetworkTopologyStrategy', 'datacenter1': '1' };
USE test;
CREATE TABLE testtable (a int, b int, s1 int static, s2 int static, v int, PRIMARY KEY (a, b));
INSERT INTO testtable (a,b,s1,s2,v) VALUES (2,2,2,null,2);
DELETE s1 FROM testtable WHERE a = 2 IF s2 IN (10,20,30);

The output is different between 2.x and 3.x:

2.x:

cqlsh:test> DELETE s1 FROM testtable WHERE a = 2 IF s2 = 5;

 [applied] | s2
-----------+------
     False | null

3.x:

cqlsh:test> DELETE s1 FROM testtable WHERE a = 2 IF s2 = 5;

 [applied]
-----------
     False

2.x would although return same result if executed on a partition that does not exist at all:

cqlsh:test> DELETE s1 FROM testtable WHERE a = 5 IF s2 = 5;

 [applied]
-----------
     False

It might be related to static column LWTs, as I could not reproduce same behaviour with non-static column LWTs. The most recent change was CASSANDRA-10532, which enabled LWT operations on static columns with partition keys only. Another possible relation is CASSANDRA-9842, which removed distinction between null column and non-existing row. (striked through since same happens on pre-CASSANDRA-9842 code.

Issue Links

• relates to: CASSANDRA-12867 Batch with multiple conditional updates for the same partition causes AssertionError