package examples; import org.mapdb.DB; import org.mapdb.DBMaker; import org.mapdb.Serializer; import java.util.Map; /** * Demonstrates how-to apply compression in various modes. *
* MapDB uses LZF compression, there is discussion to support other compression alghorithms * */ public class Compression { public static void main(String[] args) { /* * first case, just enable storage wide compression for all records. */ DB db = DBMaker.newMemoryDB() .compressionEnable() //this settings enables compression .make(); //and now create and use map as usual Map map = db.getTreeMap("test"); map.put("some","stuff"); /* * Other option is to use compression only for specific part. For example if * you have large values, you may want to compress them. It may make sense * not to compress BTree Nodes and Keys. */ DB db2 = DBMaker.newMemoryDB().make(); //no store wide compression this time //construct value serializier, use default serializier Serializer valueSerializer = db2.getDefaultSerializer(); //but wrap it, to compress its output valueSerializer = new Serializer.CompressionWrapper(valueSerializer); //now construct map, with additional options Map map2 = db2.createTreeMap("test") .valuesOutsideNodesEnable() // store values outside of BTree Nodes. Faster reads if values are large. .valueSerializer(valueSerializer) //set our value serializer. .make(); map2.put("some","stuff"); } }