Given a database instance and a query on it whose result is initially non-empty, the resilience decision problem is to decide if there exist a small enough number of facts in the database instance such that the deletion of these facts empties the result of the given query. In this paper, we revisit the resilience decision problem. We investigate the parameterized complexity for various classes of database queries. We consider the factors including the query size and the number of variables, and present several intractable cases even from the perspective of parameterized complexity. Meanwhile, we refine the characteristics of resilience for self-join-free conjunctive queries containing triads, and show that it is still NP-hard even if the structure of the input database instance is simple. This result implies the hardness essentially comes from the parity of triangle sequence instead of the complicate (non-planar) intersections of cycles. On the other hand, we also obtain some positive results showing that the resilience decision problem is still fixed parameter tractable for an important case through kernelization. Our work demonstrates a new insight for employing resilience computation in database operations.

给定一个数据库实例及其查询，其结果最初为非空，则弹性决策问题是确定数据库实例中是否存在足够少的事实，从而删除这些事实就可以清空给定的结果查询。在本文中，我们重新审视了弹性决策问题。我们研究了各种类型的数据库查询的参数化复杂性。我们考虑了包括查询大小和变量数量在内的因素，并且即使从参数化复杂性的角度来看，也存在几种棘手的情况。同时，我们改进了包含三元组的无自连接合取查询的弹性特性，并表明即使输入数据库实例的结构简单，它仍然是NP难的。该结果表明硬度基本上来自三角形序列的奇偶性，而不是复杂的（非平面）循环交点。另一方面，我们还获得了一些积极的结果，这些结果表明，通过重要化，弹性决策问题对于重要的情况仍然是可处理的固定参数。我们的工作展示了在数据库操作中采用弹性计算的新见解。