MVStore with custom sort order Comparator?

[ivan]

Hi,

  for the key order, is it possible to allow user defined custom sort order using java comparator?

Thanks

[Noel Grandin]

No, but you can create custom datatypes and supply your own comparison operation

org.h2.mvstore.type.DataType#compare(Object, Object)

​

[ivan]

Hi,

 Thanks for the tips but I got this error : 

Any help?  :-P 

Thanks

Exception in thread "main" java.lang.IllegalArgumentException: Could not serialize String2@12faeca [1.4.197/0]

at org.h2.mvstore.DataUtils.newIllegalArgumentException(DataUtils.java:844)

at org.h2.mvstore.type.ObjectDataType.serialize(ObjectDataType.java:359)

at org.h2.mvstore.type.ObjectDataType$SerializedObjectType.write(ObjectDataType.java:1535)

at org.h2.mvstore.type.ObjectDataType.write(ObjectDataType.java:127)

at org.h2.mvstore.type.ObjectDataType.write(ObjectDataType.java:121)

at org.h2.mvstore.Page.write(Page.java:745)

at org.h2.mvstore.Page.writeUnsavedRecursive(Page.java:828)

at org.h2.mvstore.MVStore.storeNowTry(MVStore.java:1108)

at org.h2.mvstore.MVStore.storeNow(MVStore.java:1016)

at org.h2.mvstore.MVStore.commitAndSave(MVStore.java:1005)

at org.h2.mvstore.MVStore.commit(MVStore.java:966)

Caused by: java.io.NotSerializableException: String2

at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1183)

at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:347)

at org.h2.mvstore.type.ObjectDataType.serialize(ObjectDataType.java:356)

... 11 more

here is my code :

================================================

import java.nio.ByteBuffer;

import org.h2.mvstore.DataUtils;

import org.h2.mvstore.WriteBuffer;

import org.h2.mvstore.type.DataType;

/**

 * A string type.

 */

public class String2 implements DataType {

    public static final String2 INSTANCE = new String2();

    @Override

    public int compare(Object a, Object b) {

        return a.toString().compareTo(b.toString());

    }

    @Override

    public int getMemory(Object obj) {

        return 24 + 2 * obj.toString().length();

    }

    @Override

    public void read(ByteBuffer buff, Object[] obj, int len, boolean key) {

        for (int i = 0; i < len; i++) {

            obj[i] = read(buff);

        }

    }

    @Override

    public void write(WriteBuffer buff, Object[] obj, int len, boolean key) {

        for (int i = 0; i < len; i++) {

            write(buff, obj[i]);

        }

    }

    @Override

    public String read(ByteBuffer buff) {

        int len = DataUtils.readVarInt(buff);

        return DataUtils.readString(buff, len);

    }

    @Override

    public void write(WriteBuffer buff, Object obj) {

        String s = obj.toString();

        int len = s.length();

        buff.putVarInt(len).putStringData(s, len);

    }

}

================================================