Query Optimization Paper
I. Abstract
The query optimizer is an important system component of a relational database management system (DBMS). It is the responsibility of this component to translate the user-submitted query - usually written in a non the database. The research literature describes a wide variety of optimization strategies for different quer y languages and implementation environments. However, very little is known about how to design and structure the query optimization component to implement these strategies. This paper proposes a first step towards the design of a modular query optimizer. We describe its operations by transformation rules which generate different QEPs from initial query specifications. As we distinguish different aspects of the query optimization process, our hope is that the approach taken in this paper will contribute to the more general goal of a modular query optimizer as part of an extensible database management system. -procedural language - into an efficient query evaluation plan (QEP) which is then executed against
II. INTRODUCTION:
Query optimization is a function of many relational database in which multiple query for satisfying a query are examined and a good query plan is identified. This may or not be the absolute best strategy because there are many ways of doing plans. There is a trade-off between the amount of time spent figuring out the best plan and the amount running the plan. Different qualities of database management systems have different ways of balancing these two. Cost based query optimizers evaluate the resource footprint of various query plans and use this as the basis for plan selection.
Typically the resources which are costed are CPU path length, amount of disk buffer space, disk storage service time, and interconnect usage between units of parallelism. The set of query plans examined is formed by examining possible access paths (e.g., primary index access, secondary index access, full file scan) and various
The query optimizer is an important system component of a relational database management system (DBMS). It is the responsibility of this component to translate the user-submitted query - usually written in a non the database. The research literature describes a wide variety of optimization strategies for different quer y languages and implementation environments. However, very little is known about how to design and structure the query optimization component to implement these strategies. This paper proposes a first step towards the design of a modular query optimizer. We describe its operations by transformation rules which generate different QEPs from initial query specifications. As we distinguish different aspects of the query optimization process, our hope is that the approach taken in this paper will contribute to the more general goal of a modular query optimizer as part of an extensible database management system. -procedural language - into an efficient query evaluation plan (QEP) which is then executed against
II. INTRODUCTION:
Query optimization is a function of many relational database in which multiple query for satisfying a query are examined and a good query plan is identified. This may or not be the absolute best strategy because there are many ways of doing plans. There is a trade-off between the amount of time spent figuring out the best plan and the amount running the plan. Different qualities of database management systems have different ways of balancing these two. Cost based query optimizers evaluate the resource footprint of various query plans and use this as the basis for plan selection.
Typically the resources which are costed are CPU path length, amount of disk buffer space, disk storage service time, and interconnect usage between units of parallelism. The set of query plans examined is formed by examining possible access paths (e.g., primary index access, secondary index access, full file scan) and various
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