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Leveled compaction strategy

As explained in ScyllaDB in Action

Leveled compaction strategy is an SSTable compaction strategy that organizes fixed-size files into levels with non-overlapping key ranges within each level.

Leveled compaction strategy (LCS) organizes fixed-sized SSTables into levels. Within each level, a partition key appears in only one SSTable, and compaction runs when a level fills. section 8.4.1 section 8.5

LCS differs from the other ScyllaDB compaction strategies in several practical ways:

  • It uses levels rather than size-based tiers, unlike size-tiered compaction strategy. section 8.4.1
  • It keeps a partition in only one SSTable per level, reducing duplicate partition placement within that level. section 8.5
  • It is one of three standard strategies alongside size-tiered and time-window compaction; size-tiered is the default. section 8.4.1

Selecting LCS for a table

Set the table's compaction strategy with CQL: ALTER TABLE reviews.authors WITH compaction = {'class': 'LeveledCompactionStrategy'};

How ScyllaDB in Action covers it

How deep it goes
Explains fixed-sized SSTables, per-level partition placement, and fill-triggered compaction without detailed sizing or tuning guidance.
Examples
Uses an ALTER TABLE statement and a figure showing fixed-sized SSTables divided into levels.
What it assumes
Assumes familiarity with SSTables and compaction while contrasting LCS with size-tiered and time-window strategies.
What you can do after
Operate/configure LCS by assigning LeveledCompactionStrategy to a ScyllaDB table with ALTER TABLE.
How it connects
Connects LCS with SSTables, memtables, minor compaction, and size-tiered and time-window compaction strategies.
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Related concepts

This explainer was generated by Manning's knowledge graph from the text of ScyllaDB in Action. The section links point to the parts of the book it draws on.