Optimization of Query Plans in the presence of Access Limitations
نویسندگان
چکیده
We consider the problem of querying data sources that have limited capabilities and can thus only be accessed by complying with certain binding patterns for their attributes. This is often the case, e.g., in the context of data on the web queryable via web forms as well as in legacy data wrapped in relational tables. In such contexts, computing the answer to a user query cannot be done as in a traditional database; instead, a query plan is needed that takes the access limitations into
منابع مشابه
Optimizing source-call ordering in Information Gathering Plans
In this paper we consider the problem of optimizing the order in which source relations are joined in information gathering plans. This problem differs significantly from the traditional database query optimization problem, as sources on the Internet have a variety of access limitations and the execution cost in information gathering is affected both by network traffic and by the connection set...
متن کاملDetermining Relevant Relations for Datalog Queries under Access Limitations is Undecidable
Access limitations are restrictions in the way in which the tuples of a relation can be accessed. Under access limitations, query answering becomes more complex than in the traditional case, with no guarantee that the answer tuples that can be extracted (aka maximal answer) are all those that would be found without access limitations (aka complete answer). The field of query answering under acc...
متن کاملQuery processing using HP NonStop SQL/MP software
Query optimization.............................................................................................................................. 3 Generating the plan ......................................................................................................................... 3 Serial execution plans ......................................................................................
متن کاملQuerying with Access Patterns and Integrity Constraints
Traditional query processing involves a search for plans formed by applying algebraic operators on top of primitives representing access to relations in the input query. But many querying scenarios involve two interacting issues that complicate the search. On the one hand, the search space may be limited by access restrictions associated with the interfaces to datasources, which require certain...
متن کاملPerformance of Query Optimization Heuristics in Object-Oriented Databases
This paper investigates the performance of query optimization heuristics in object-oriented databases. Query optimization involves the following two stages : (1) Reduce the search space of access plans for a query to be considered during query evaluation using optimization heuristics (2) Estimate the cost of each access plan in (1) and select the cheapest access plan. To compute the cost of eac...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2007