CavalliumDB Engine

A very simple reactive wrapper for RocksDB and Lucene.

This is not a database, but only a wrapper for Lucene Core and RocksDB, with a bit of abstraction.

Features

• RocksDB key-value database engine

  • Snapshots
  • Multi-column database
  • Write-ahead log and corruption recovery
  • Multiple data types:
    • Single value (Singleton)
    • Map (Dictionary)
    • Composable nested map (Deep dictionary)
  • Customizable data serializers
  • Values codecs
  • Update-on-write value versioning using versioned codecs

• Apache Lucene Core indexing library

  • Snapshots
  • Documents structure
  • Sorting
    • Ascending and descending
    • Numeric or non-numeric
  • Searching
    • Nested search terms
    • Combined search terms
    • Fuzzy text search
    • Coordinates, integers, longs, strings, text
  • Indicization and analysis
    • N-gram
    • Edge N-gram
    • English words
    • Stemming
    • Stopwords removal
  • Results filtering

F.A.Q.

• Why is it so difficult to use?

  This is not a DBMS.

  This is an engine on which a DBMS can be built upon; for this reason it's very difficult to use directly without building another abstraction layer on top.

• Can I use objects instead of byte arrays?

  Yes, you must serialize/deserialize them using a library of your choice.

  CodecSerializer allows you to implement versioned data using a codec for each data version. Note that it uses 1 to 4 bytes more for each value to store the version.

• Why there is a snapshot function for each database part?

  Since RocksDB and lucene indices are different software, you can't take a snapshot of everything in the same instant.

  A single snapshot must be implemented as a collection of all the snapshots.

• Is CavalliumDB Engine suitable for your project?

  No.

  This engine is largely undocumented, and it doesn't provide extensive tests.

Examples

In src/example/java you can find some quick implementations of each core feature.