ZhaoYang created CASSANDRA-15640:
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Summary: digest may not match when single partition named queries
skip older sstables
Key: CASSANDRA-15640
URL: https://issues.apache.org/jira/browse/CASSANDRA-15640
Project: Cassandra
Issue Type: Bug
Components: Legacy/Local Write-Read Paths
Reporter: ZhaoYang
Name queries (aka. single partition query with full clustering keys) query
sstables sequentially in recency order, in the hope that most recent sstables
will contain most recent data, so that they can avoid reading older sstables in
{{SinglePartitionReadCommand#reduceFilter}}.
Unfortunately, this optimization may cause digest mismatch if older sstables
contain range tombstone or row deletion with lower timestamp. [Test
Code|https://github.com/jasonstack/cassandra/commit/3dfa29bb34bc237ab2b68f849906c09569c5cc94]
{code:java}
Table with (pk, ck1, ck2)
Node1:
* delete row (pk=1, ck1=1) with ts=10
* insert row (pk=1, ck1=1, ck2=1) with ts=11
Node2:
* delete row (pk=1, ck1=1) with ts=10
* flush into sstable1
* insert row (pk=1, ck1=1, ck2=1) with ts=11
* flush into sstable2
Query with pk=1 and ck1=1 and ck2=1
* node1 returns: RT open marker, row, RT close marker
* node2 returns: row (because sstable1 is skipped)
Note: similar mismatch can happen with row deletion as well.
{code}
In the above example: Is it safe to ignore RT or row deletion if row liveness
has higher timestamp for named queries in node1?
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