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SSTable ms Index: Trie-Based Format¶
The ms format introduces a trie-based partition index, replacing the previous
Cassandra 3.0 index format used by me and md.
Benefits¶
Compared to the previous format, the trie-based index provides:
Reduced memory footprint - less in-memory index data per SSTable.
Faster partition lookups - more efficient index traversal.
Smaller on-disk index files - shared key prefixes reduce redundant storage.
Configuring ms Format¶
New Clusters (2026.2 and Later)¶
Starting with ScyllaDB 2026.2, ms is the default value for sstable_format in the
default scylla.yaml. Clusters created with ScyllaDB 2026.2 use the ms format unless
the configuration is changed.
Upgraded Clusters¶
Clusters upgraded from an earlier version continue to use the format specified in their
scylla.yaml. To switch to the ms format, add the following to scylla.yaml:
sstable_format: ms
After the node configuration is updated, newly created SSTables will use the ms format.
Existing SSTables are not automatically converted. They will be rewritten in ms format
during the next compaction. Conversion can be triggered using nodetool upgradesstables -a
after updating the node configuration.