A top-k query retrieves the best k tuples by assigning scores for each tuple in a target relation with respect to a user-specific scoring function. This paper studies the problem of constructing an indexing structure for supporting top-k queries over varying scoring functions and retrieval sizes. The existing research efforts can be categorized into three approaches: list-, layer-, and view-based approaches. In this paper, we mainly focus on the layer-based approach that pre-materializes tuples into consecutive multiple layers. We first propose a dual-resolution layer that consists of coarse-level and fine-level layers. Specifically, we build coarse-level layers using skylines, and divide each coarse-level layer into fine-level sublayers using convex skylines. To make our proposed dual-resolution layer scalable, we then address the following optimization directions: 1) index construction; 2) disk-based storage scheme; 3) the design of the virtual layer; and 4) index maintenance for tuple updates. Our evaluation results show that our proposed method is more scalable than the state-of-the-art methods.

This paper discusses the problem of map translation, of servicing spatial entities in multiple languages. Existing work on entity translation harvests translation evidence from text resources, not considering spatial locality in translation. In contrast, we mine geo-tagged sources for multilingual tags to improve recall, and consider spatial properties of tags for translation to improve precision. Our approach empirically improves accuracy from 0.562 to 0.746 using Taiwanese spatial entities.