Sylvain Lebresne created CASSANDRA-15805:
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Summary: Potential duplicate rows on 2.X->3.X upgrade when
multi-rows range tombstones interacts with collection tombstones
Key: CASSANDRA-15805
URL: https://issues.apache.org/jira/browse/CASSANDRA-15805
Project: Cassandra
Issue Type: Bug
Components: Consistency/Coordination, Local/SSTable
Reporter: Sylvain Lebresne
The legacy reading code ({{LegacyLayout}} and
{{UnfilteredDeserializer.OldFormatDeserializer}}) does not handle correctly the
case where a range tombstone covering multiple rows interacts with a collection
tombstone.
A simple example of this problem is if one runs on 2.X:
{noformat}
CREATE TABLE t (
k int,
c1 text,
c2 text,
a text,
b set<text>,
c text,
PRIMARY KEY((k), c1, c2)
);
// Delete all rows where c1 is 'A'
DELETE FROM t USING TIMESTAMP 1 WHERE k = 0 AND c1 = 'A';
// Inserts a row covered by that previous range tombstone
INSERT INTO t(k, c1, c2, a, b, c) VALUES (0, 'A', 'X', 'foo', {'whatever'},
'bar') USING TIMESTAMP 2;
// Delete the collection of that previously inserted row
DELETE b FROM t USING TIMESTAMP 3 WHERE k = 0 AND c1 = 'A' and c2 = 'X';
{noformat}
If the following is ran on 2.X (with everything either flushed in the same
table or compacted together), then this will result in the inserted row being
duplicated (one part containing the {{a}} column, the other the {{c}} one).
I will note that this is _not_ a duplicate of CASSANDRA-15789 and this
reproduce even with the fix to {{LegacyLayout}} of this ticket. That said, the
additional code added to CASSANDRA-15789 to force merging duplicated rows if
they are produced _will_ end up fixing this as a consequence (assuming there is
no variation of this problem that leads to other visible issues than duplicated
rows). That said, I "think" we'd still rather fix the source of the issue.
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