Dynamic Query Re-Optimization

نویسندگان

  • Kenneth W. Ng
  • Zhenghao Wang
  • Richard R. Muntz
  • Silvia Nittel
چکیده

Very long-running queries in database systems are not uncommon in non-traditional application domains such as image processing or data warehousing analysis. Query optimization, therefore, is important. However, estimates of the query characteristics before query execution are usually inaccurate. Further, system conngu-ration and resource availability may change during long evaluation period. As a result, queries are often evaluated with sub-optimal plan conngurations. To remedy this situation, we have designed a novel approach to re-optimize suboptimal query plan conngurations on-they with Conquest | an extensible and distributed query processing system. A dynamic optimizer considers reconnguration cost as well as execution cost in determining the best query plan connguration. Experimental results are presented.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Dynamic Plan Migration for Snapshot-Equivalent Continuous Queries in Data Stream Systems

A data stream management system executes a large number of continuous queries in parallel. As stream characteristics and query workload change over time, the plan initially installed for a continuous query may become inefficient. As a consequence, the query optimizer will re-optimize this plan based on the current statistics. The replacement of the running plan with a more efficient but semanti...

متن کامل

Relational Databases Query Optimization using Hybrid Evolutionary Algorithm

Optimizing the database queries is one of hard research problems. Exhaustive search techniques like dynamic programming is suitable for queries with a few relations, but by increasing the number of relations in query, much use of memory and processing is needed, and the use of these methods is not suitable, so we have to use random and evolutionary methods. The use of evolutionary methods, beca...

متن کامل

Global Query Optimization Based on Multistate Cost Models for a Dynamic Multidatabase System

Global query optimization in a multidatabase system (MDBS) is a challenging issue since some local optimization information such as local cost models may not be available at the global level due to local autonomy. It becomes even more difficult when dynamic environmental factors are taken into consideration. In our previous work, a qualitative approach was suggested to build so-called multistat...

متن کامل

Title : Dynamic Re - grouping of Continuous Queries

In this paper, we design and evaluate an efficient and dynamic regrouping approach to optimize a large continuous query workload. The key idea of our regrouping algorithm is to find a best solution by removing redundant groups within the existing solution from incremental group optimization. Since the existing query groups usually constitute a very small portion of the entire search space, such...

متن کامل

Evolution of Query Optimization Methods

Query optimization is the most critical phase in query processing. In this paper, we try to describe synthetically the evolution of query optimization methods from uniprocessor relational database systems to data Grid systems through parallel, distributed and data integration systems. We point out a set of parameters to characterize and compare query optimization methods, mainly: (i) size of th...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 1999