These settings are available in system.merge_tree_settings and are autogenerated from the ClickHouse snapshot.
materialize_skip_indexes_on_merge
When enabled, merges build and store skip indices for new parts. Otherwise they can be created/stored by explicit MATERIALIZE INDEX or during INSERTs.
See also exclude_materialize_skip_indexes_on_merge for more fine-grained control.
materialize_statistics_on_merge
When enabled, merges will build and store statistics for new parts. Otherwise they can be created/stored by explicit MATERIALIZE STATISTICS or during INSERTs
materialize_ttl_recalculate_only
Only recalculate ttl info when MATERIALIZE TTL