Cooperative Update Exchange in the Youtopia System

TL;DR

The paper introduces a cooperative update exchange model for Youtopia that combines deterministic change propagation with human control, allowing cycle handling and conflict management in collaborative data systems.

Contribution

It presents a novel hybrid change propagation model integrating deterministic chase with user intervention, enabling cycle handling and conflict serializability in collaborative data management.

Findings

The model permits cycles without losing correctness.

Two notions of serializability are introduced to prevent harmful interference.

An optimistic algorithm with abort reduction techniques is developed and tested.

Abstract

Youtopia is a platform for collaborative management and integration of relational data. At the heart of Youtopia is an update exchange abstraction: changes to the data propagate through the system to satisfy user-specified mappings. We present a novel change propagation model that combines a deterministic chase with human intervention. The process is fundamentally cooperative and gives users significant control over how mappings are repaired. An additional advantage of our model is that mapping cycles can be permitted without compromising correctness. We investigate potential harmful interference between updates in our model; we introduce two appropriate notions of serializability that avoid such interference if enforced. The first is very general and related to classical final-state serializability; the second is more restrictive but highly practical and related to conflict-serializability. We present an algorithm to enforce the latter notion. Our algorithm is an optimistic one, and as such may sometimes require updates to be aborted. We develop techniques for reducing the number of aborts and we test these experimentally.