Hints : DRIVING_SITE

最新推荐文章于 2025-12-20 13:10:13 发布

转载最新推荐文章于 2025-12-20 13:10:13 发布 · 108 阅读

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#数据库

本文介绍了Oracle SQL中的DRIVING_SITE提示使用方法，该提示强制查询在不同于Oracle选择的站点执行。通过示例展示了如何利用此提示改变JOIN操作的位置，从而优化远程数据处理效率。

The DRIVING_SITE hint forces query execution to be done at a different site than that
selected by Oracle. This hint can be used with either rule-based or cost-based
optimization. Table is the name or alias for the table at which site the execution should
take place.

SELECT /*+ DRIVING_SITE(DEPT) */ *
FROM EMP, DEPT@RSITE
WHERE EMP.DEPTNO = DEPT.DEPTNO;

If this query is executed without the hint, rows from DEPT will be sent to the local site
and the join will be executed there. With the hint, the rows from EMP will be sent to the
remote site and the query will be executed there, returning the result to the local site.

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