On-Demand Query Result Cleaning

Incomplete data is ubiquitous. When a user issues a query over incomplete data, the results may contain incomplete data as well. If a user requires high precision query results, or current estimation algorithms fail to make accurate estimates on incomplete data, data collection by humans may instead be used to find values for, or to confirm this incomplete data. We propose an approach that incrementally confirms incomplete data: First, queries on incomplete data are processed by a probabilistic database system. Incomplete data in the query results is represented in a form called candidate questions. Second, we incrementally solicit user feedback to confirm candidate questions. The challenge of this approach is to determine in what order to confirm candidate questions with the user. To solve this, we design a framework for ranking candidate questions for user confirmation using a concept that we call cost of perfect information (CPI). The core component of CPI is a penalty function that is based on entropy. We compare each candidate question’s CPI and choose an optimal candidate question to solicit user feedback. Our approach achieves accurate query results with low confirmation and computation costs. Experiments on a real dataset show that our approach outperforms other strategies.