Subproperties of compaction
Constructing a map of the compaction property and its subproperties.
Using CQL, you can configure compaction for a table by constructing a map of the compaction property and the following subproperties:
|Compaction Subproperties||Description||Default||Supported Strategy|
|bucket_high||Size-tiered compaction strategy (STCS) considers SSTables to be within the same bucket if the SSTable size diverges by 50% or less from the default bucket_low and default bucket_high values: [average-size × bucket_low, average-size × bucket_high].||1.5||STCS|
|bucket_low||Same as above.||0.5||STCS|
|max_threshold||In SizeTieredCompactionStrategy, sets the maximum number of SSTables to allow in a minor compaction. In LeveledCompactionStrategy, it applies to L0 when L0 gets behind, that is, when L0 accumulates more than MAX_COMPACTING_L0 SSTables.||32||STCS|
|min_threshold||In SizeTieredCompactionStrategy sets the minimum number of SSTables to trigger a minor compaction.||4||STCS|
|min_sstable_size||The SizeTieredCompactionStrategy groups SSTables for compaction into buckets. The bucketing process groups SSTables that differ in size by less than 50%. This results in a bucketing process that is too fine grained for small SSTables. If your SSTables are small, use min_sstable_size to define a size threshold (in bytes) below which all SSTables belong to one unique bucket.||50MB||STCS|
|sstable_size_in_mb||The target size for SSTables that use the leveled compaction strategy (LCS). Although SSTable sizes should be less or equal to sstable_size_in_mb, it is possible to have a larger SSTable during compaction. This occurs when data for a given partition key is exceptionally large. The data is not split into two SSTables.||160MB||LCS|
|tombstone_compaction_interval||The minimum time to wait after an SSTable creation time before considering the SSTable for tombstone compaction. Tombstone compaction is the compaction triggered if the SSTable has more garbage-collectable tombstones than tombstone_threshold.||1 day||all|
|tombstone_threshold||A ratio of garbage-collectable tombstones to all contained columns, which if exceeded by the SSTable triggers compaction (with no other SSTables) for the purpose of purging the tombstones.||0.2||all|
To disable background compactions, use nodetool disableautocompaction/enableautocompaction instead of setting min/max compaction thresholds to 0.
Attention: Be sure this document version matches your product version!