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https://issues.apache.org/jira/browse/CASSANDRA-13153?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15868143#comment-15868143
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Blake Eggleston commented on CASSANDRA-13153:
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bq. shouldn't we get rid of anti-compactions for full repairs in 2.2+ as well?
I think we're ok leaving them as is. Using pre 4.0 incremental repairs is root
cause of this. If operators stop using incremental repairs, there's no harm in
doing an anticompaction after a full repair. The only scenario it would cause
problems is when using incremental repair for the first time after upgrading to
4.0, when the repaired datasets are very likely inconsistent. This could be
addressed by just running a final full repair on the upgraded cluster. As part
of CASSANDRA-9143, full repairs no longer perform anticompaction, and streamed
sstables include the repairedAt time, which would bring the repaired and
unrepaired datasets in sync.
So having said all that, it seems like we should recommend that users who
delete data:
1. Stop using incremental repair (pre-4.0)
2. Run a full repair after upgrading to 4.0 before using incremental repair
again
We should also recommend that even if users don't delete data, they should take
a look at the amount of streaming their incremental repair is doing, and decide
if it might be less expensive to just do full repairs instead.
Thoughts?
> Reappeared Data when Mixing Incremental and Full Repairs
> --------------------------------------------------------
>
> Key: CASSANDRA-13153
> URL: https://issues.apache.org/jira/browse/CASSANDRA-13153
> Project: Cassandra
> Issue Type: Bug
> Components: Compaction, Tools
> Environment: Apache Cassandra 2.2
> Reporter: Amanda Debrot
> Labels: Cassandra
> Attachments: log-Reappeared-Data.txt,
> Step-by-Step-Simulate-Reappeared-Data.txt
>
>
> This happens for both LeveledCompactionStrategy and
> SizeTieredCompactionStrategy. I've only tested it on Cassandra version 2.2
> but it most likely also affects all Cassandra versions after 2.2, if they
> have anticompaction with full repair.
> When mixing incremental and full repairs, there are a few scenarios where the
> Data SSTable is marked as unrepaired and the Tombstone SSTable is marked as
> repaired. Then if it is past gc_grace, and the tombstone and data has been
> compacted out on other replicas, the next incremental repair will push the
> Data to other replicas without the tombstone.
> Simplified scenario:
> 3 node cluster with RF=3
> Intial config:
> Node 1 has data and tombstone in separate SSTables.
> Node 2 has data and no tombstone.
> Node 3 has data and tombstone in separate SSTables.
> Incremental repair (nodetool repair -pr) is run every day so now we have
> tombstone on each node.
> Some minor compactions have happened since so data and tombstone get merged
> to 1 SSTable on Nodes 1 and 3.
> Node 1 had a minor compaction that merged data with tombstone. 1
> SSTable with tombstone.
> Node 2 has data and tombstone in separate SSTables.
> Node 3 had a minor compaction that merged data with tombstone. 1
> SSTable with tombstone.
> Incremental repairs keep running every day.
> Full repairs run weekly (nodetool repair -full -pr).
> Now there are 2 scenarios where the Data SSTable will get marked as
> "Unrepaired" while Tombstone SSTable will get marked as "Repaired".
> Scenario 1:
> Since the Data and Tombstone SSTable have been marked as "Repaired"
> and anticompacted, they have had minor compactions with other SSTables
> containing keys from other ranges. During full repair, if the last node to
> run it doesn't own this particular key in it's partitioner range, the Data
> and Tombstone SSTable will get anticompacted and marked as "Unrepaired". Now
> in the next incremental repair, if the Data SSTable is involved in a minor
> compaction during the repair but the Tombstone SSTable is not, the resulting
> compacted SSTable will be marked "Unrepaired" and Tombstone SSTable is marked
> "Repaired".
> Scenario 2:
> Only the Data SSTable had minor compaction with other SSTables
> containing keys from other ranges after being marked as "Repaired". The
> Tombstone SSTable was never involved in a minor compaction so therefore all
> keys in that SSTable belong to 1 particular partitioner range. During full
> repair, if the last node to run it doesn't own this particular key in it's
> partitioner range, the Data SSTable will get anticompacted and marked as
> "Unrepaired". The Tombstone SSTable stays marked as Repaired.
> Then it’s past gc_grace. Since Node’s #1 and #3 only have 1 SSTable for that
> key, the tombstone will get compacted out.
> Node 1 has nothing.
> Node 2 has data (in unrepaired SSTable) and tombstone (in repaired
> SSTable) in separate SSTables.
> Node 3 has nothing.
> Now when the next incremental repair runs, it will only use the Data SSTable
> to build the merkle tree since the tombstone SSTable is flagged as repaired
> and data SSTable is marked as unrepaired. And the data will get repaired
> against the other two nodes.
> Node 1 has data.
> Node 2 has data and tombstone in separate SSTables.
> Node 3 has data.
> If a read request hits Node 1 and 3, it will return data. If it hits 1 and
> 2, or 2 and 3, however, it would return no data.
> Tested this with single range tokens for simplicity.
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