David Capwell created CASSANDRA-20398:
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Summary: Unified Compaction does not properly validate min and
target sizes
Key: CASSANDRA-20398
URL: https://issues.apache.org/jira/browse/CASSANDRA-20398
Project: Apache Cassandra
Issue Type: Bug
Components: Local/Compaction/UCS
Reporter: David Capwell
{code}
AND compaction = {'base_shard_count': '7', 'class':
'org.apache.cassandra.db.compaction.UnifiedCompactionStrategy',
'flush_size_override': '492E+207 KiB', 'min_sstable_size': '871 GiB',
'provide_overlapping_tombstones': 'CELL', 'target_sstable_size': '12E899 B'}
{code}
In this example min_sstable_size < target_sstable_size but the error the user
sees is
{code}
Caused by: org.apache.cassandra.exceptions.ConfigurationException: Invalid
configuration, min_sstable_size (871.000GiB) should be less than the target
size minimum: 2.000GiB at
org.apache.cassandra.db.compaction.unified.Controller.validateOptions(Controller.java:627)
at
org.apache.cassandra.db.compaction.UnifiedCompactionStrategy.validateOptions(UnifiedCompactionStrategy.java:106)
{code}
The variables in question for this error
{code}
targetSSTableSize = 9223372036854775807
sizeInBytes = 935229128704
limit = 2147483647 // (int) (targetSSTableSize * Math.sqrt(0.5))
{code}
The issue here is that the target size is larger than int max so we wrap around!
{code}
sizeInBytes >= Math.ceil(targetSSTableSize * INVERSE_SQRT_2) == false
sizeInBytes >= (int) Math.ceil(targetSSTableSize * INVERSE_SQRT_2) == true
{code}
Here is another example where the error isn't clear but isn't due to wrap
arround
{code}
AND compaction = {'base_shard_count': '2', 'class':
'org.apache.cassandra.db.compaction.UnifiedCompactionStrategy',
'min_sstable_size': '437.825 MiB', 'scaling_parameters':
'T2,N,1961141729,-163573937,L10,L3,T4,N,N', 'target_sstable_size': '+565 MiB'}
{code}
{code}
Caused by: org.apache.cassandra.exceptions.ConfigurationException: Invalid
configuration, min_sstable_size (437.825MiB) should be less than the target
size minimum: 399.515MiB
at
org.apache.cassandra.db.compaction.unified.Controller.validateOptions(Controller.java:627)
{code}
Here the same variables above are
{code}
targetSSTableSize = 592445440
sizeInBytes = 459092787
limit = 418922189
{code}
This looks to be due to the 70% (INVERSE_SQRT_2) on the target, so the error
uses a value the user doesn't provide but rather one that is calculated.
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