Implementation:Lance format Lance Java RestoreOp

Knowledge Sources	Lance
Domains	Java_SDK, Dataset_Management
Last Updated	2026-02-08 19:33 GMT

Overview

Description

The Restore class is an immutable operation that reverts a Lance dataset to a previously committed version. It implements the Operation interface and carries a single long field representing the target version number.

Lance datasets maintain automatic versioning where every write creates a new version. The Restore operation leverages this by creating a new version whose contents match a specified historical version. This is a zero-copy operation on the data layer since it only updates the manifest to point to the existing data of the target version.

Usage

Use Restore to roll back a dataset to a known good state after a problematic write, or to implement point-in-time recovery. The restored version becomes the latest version of the dataset.

Code Reference

Source Location

java/src/main/java/org/lance/operation/Restore.java

Signature

public class Restore implements Operation {
    public static Builder builder();
    public long version();
    public String name();  // returns "Restore"
}

Import

import org.lance.operation.Restore;

I/O Contract

Inputs

Parameter	Type	Required	Description
version	long	Yes	The dataset version number to restore to

Outputs

Return	Type	Description
version()	long	The target version number
name()	String	Returns "Restore" for JNI dispatch

Usage Examples

// Restore the dataset to version 5
Restore restoreOp = Restore.builder()
    .version(5L)
    .build();

long targetVersion = restoreOp.version(); // 5
String opName = restoreOp.name(); // "Restore"

Related Pages

• Lance_format_Lance_Java_OverwriteOp -- Overwrites dataset content (creates a new version)
• Lance_format_Lance_Java_DeleteOp -- Deletes rows (creates a new version that may need rollback)