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  1. 2008.03.11 [펌] 9. Tuning Distributed Queries

[펌] 9. Tuning Distributed Queries

ITWeb/스크랩 2008.03.11 17:28

ref. http://download.oracle.com/docs/cd/A58617_01/server.804/a58246/distrib.htm

remote and distributed query 에 대한 성능 정보를 찾다가 oracle tuning 에서 이런게 있길래 퍼왔습니다.

Summary: Optimizing Performance of Distributed Queries

You can improve performance of distributed queries in several ways:

  • Choose the best SQL statement.

    In many cases there are several SQL statements which can achieve the same result. If all tables are on the same database, the difference in performance between these SQL statements might be minimal; but if the tables are located on different databases, the difference in performance might be bigger.

  • Use cost-based optimization.

    Cost-based optimization can use indexes on remote tables, considers more execution plans than rule-based optimization, and generally gives better results. With cost-based optimization performance of distributed queries is generally satisfactory. Only in rare occasions is it necessary to change SQL statements, create views, or use procedural code.

  • Use views.

    In some situations, views can be used to improve performance of distributed queries; for example:

    • to join several remote tables on the remote database
    • to send a different table through the network
  • Use procedural code.

    In some rare occasions it can be more efficient to replace a distributed query by procedural code, such as a PL/SQL procedure or a precompiler program. Note that this option is mentioned here only for completeness, not because it is often needed.

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