[CASSANDRA-19007] Queries with multi-column replica-side filtering can miss rows - ASF JIRA

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Details

Type: Bug
Status: Open
Priority: Normal
Resolution: Unresolved
Fix Version/s: 5.0.x, 5.x
Component/s: Consistency/Coordination
Labels:
None

Bug Category:
Correctness - Consistency
Severity:
Normal
Complexity:
Challenging
Discovered By:
Code Inspection
Platform:

All
Impacts:

None
Since Version:

0.3

Description

SELECT queries with multi-column replica-side filtering can miss rows if the filtered columns are spread across out-of-sync replicas. This dtest reproduces the issue:

@Test
public void testMultiColumnReplicaSideFiltering() throws IOException
{
    try (Cluster cluster = init(Cluster.build().withNodes(2).start()))
    {
        cluster.schemaChange(withKeyspace("CREATE TABLE %s.t (k int PRIMARY KEY, a int, b int)"));

        // insert a split row
        cluster.get(1).executeInternal(withKeyspace("INSERT INTO %s.t(k, a) VALUES (0, 1)"));
        cluster.get(2).executeInternal(withKeyspace("INSERT INTO %s.t(k, b) VALUES (0, 2)"));

        String select = withKeyspace("SELECT * FROM %s.t WHERE a = 1 AND b = 2 ALLOW FILTERING");
        Object[][] initialRows = cluster.coordinator(1).execute(select, ALL);
        assertRows(initialRows, row(0, 1, 2)); // not found!!
    }
}

This edge case affects queries using ALLOW FILTERING or any index implementation.

It affects all branches since multi-column replica-side filtering queries were introduced, long before 3.0.

The protection mechanism added by ~~CASSANDRA-8272~~/8273 won't deal with this case, since it only solves single-column conflicts where stale rows could resurrect. This bug however doesn't resurrect data, it can only miss rows while the replicas are out-of-sync.