About me:Oracle ACE pro,optimistic,passionate and harmonious. Focus on ORACLE,MySQL and other database programming,peformance tuning,db design, j2ee,Linux/AIX,Architecture tech,etc
全部博文(191)
发布时间:2022-04-14 14:11:00
My Oracle SQL Tuning Roadmap,包括sql优化的本质,sql tuning roadmap方法论, sql tuning sample以及execution plan etc,......【阅读全文】
发布时间:2022-04-14 14:09:18
My Oracle SQL Tuning Roadmap,包括sql优化的本质,sql tuning roadmap方法论, sql tuning sample以及execution plan etc,......【阅读全文】
发布时间:2022-04-12 10:46:03
SQL> DROP TABLE t;SQL> CREATE TABLE t AS SELECT * FROM dba_objects;SQL> INSERT INTO t SELECT * FROM t;SQL> commit;SQL> SELECT COUNT(*) FROM t;----------已更新999行。索引已创建。PL/SQL 过程已成功完成。 1.COUNT统计NULL的数据执行计划Plan hash v.........【阅读全文】
发布时间:2022-04-12 10:26:22
选择组合索引的前导列,必须根据具体的业务(SQL)写法不同而不同,很多书本或网上都说,前导列要选择高选择性的,但是,脱离具体的业务,这些是没有意义的,
本文就举一些常见的例子来分析下如何正确选择前导列,以抛砖引玉,实际应用中,有更多复杂的情况需要具体分析。......【阅读全文】
发布时间:2022-04-11 14:34:30
一个非常简单的SQL如何优化,类似于:SELECT *
FROM (SELECT ROW_NUMBER() OVER(PARTITION BY owner ORDER BY created) RN, T.*
FROM T)
WHERE RN = 1;......【阅读全文】
吻的感觉适2025-07-18 23:11
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