Data types

HestiaStore supports a variety of data types for storing keys and values in a binary-efficient and consistent manner. Each data type is associated with a TypeDescriptor, which handles serialization, deserialization, comparison, and hashing logic.

Below is a list of the supported data types and their characteristics.

Java Class	TypeDescriptor Class	Max Length (Bytes)	Notes
java.lang.Byte	TypeDescriptorByte	1	Two's complement representation
java.lang.Integer	TypeDescriptorInteger	4	Big-endian encoding
java.lang.Long	TypeDescriptorLong	8	Big-endian encoding
java.lang.Float	TypeDescriptorFloat	4	IEEE 754 format
java.lang.Double	TypeDescriptorDouble	8	IEEE 754 format
java.lang.String	TypeDescriptorShortString	128	UTF-8 encoding, prefixed with 2-byte length
java.lang.String	TypeDescriptorString	2 GB	UTF-8 encoding, prefixed with 2-byte length
hestia.datatype.ByteArray	TypeDescriptorByteArray	n	Raw bytes, length determined by actual data

Custom Data Types

HestiaStore allows advanced users to define custom TypeDescriptor implementations for handling specialized serialization strategies or complex types. Main usecases:

• Allows to store new data type.
• Introduce some specific encoding. it could lead to space saving.
• Limit data to some exact size

To create a new data type:

1. Implement the TypeDescriptor<T> interface. It's just a collection of simple interfaces which allows store data type to bytes and restore it from byte array
2. Optionallly register it using org.hestiastore.index.sst.DataTypeDescriptorRegistry.addTypeDescriptor(Class, descriptor).

How to use new Data Type

During Index configuration new data type descriptor can by directly used:

IndexConfiguration<Integer, Integer> conf = IndexConfiguration
    .<Integer, Integer>builder()//
    .withKeyClass(Integer.class)//
    .withValueClass(MySuperDataType.class)//
        ...
    .withValueTypeDescriptor(new TypeDescriptorMySuperDataType()) //
        ...
    .build();

Index<Integer, Integer> index = Index.<Integer, Integer>create(directory, conf);

Notes

• All numeric types use big-endian byte order for consistent sorting and comparison.
• ByteArray is a wrapper class designed to support equals(), hashCode(), and lexicographic comparison. It can be used for binary blobs or hash digests.