One of the advantages of logic programming is the fact that it offers many sources of implicit parallelism, such as and-parallelism and or-parallelism. A major problem that a parallel model must address consists in represent the multiple values that shared variables can be binded to when exploited in parallel. Binding Arrays and Environment Copying are two or-parallel models that efficiently solve that problem. Recently, research in combining independent and-parallelism and or-parallelism within the same system has led to two new binding representation approaches: the Sparse Binding Array (an evolution of binding arrays) and the Copy-On-Write binding models.

In this paper, we investigate whether for or-parallelism the newer models are practical alternatives to copying. To address this question, we experimented with YapOr, an or-parallel copying system using the YAP Prolog engine, and we implemented the Sparse Binding Array (SBA) and the Copy-On-Write (COWL) over the original system. The three alternative systems share schedulers and the underlying engine; they differ only in their binding scheme. We compared their performance on a set of well-known all-solutions benchmarks.