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RocksDB

RocksDB is often used as Crux’s primary kv-store.

In order to use RocksDB within Crux, you must first add RocksDB as a project dependency:

Project Dependency

  juxt/crux-rocksdb {:mvn/version "20.09-1.11.0-beta"}

Starting a node using RocksDB

(defn start-rocks-node [storage-dir]
  (crux/start-node {:crux.node/topology '[crux.standalone/topology
                                          crux.kv.rocksdb/kv-store]
                    :crux.standalone/event-log-dir (io/file storage-dir "event-log")
                    :crux.standalone/event-log-kv-store 'crux.kv.rocksdb/kv
                    :crux.kv/db-dir (str (io/file storage-dir "indexes"))}))

Please note that when configuring a standalone node with persisted indexes (via :crux.kv/db-dir), you should always have the tx-log and document-store persisted as well (via :crux.standalone/event-log-dir). Crux does not currently enforce this constraint or disallow otherwise invalid topology combinations.

You can create a node with custom RocksDB options by passing extra keywords in the topology. These are:

  • :crux.kv.rocksdb/disable-wal?, which takes a boolean (if true, disables the write ahead log)

  • :crux.kv.rocksdb/db-options, which takes a RocksDB 'Options' object (see more here, from the RocksDB javadocs)

To include RocksDB metrics in monitoring crux.kv.rocksdb/kv-store-with-metrics should be included in the topology map instead of the above.