1. Not so long time ago, I got a report from customer. It's reported that they had a report getted very slow and finally throw an error. I finded fout the problem sql in source code and excuted it in sql managment studio. It costs 1 minute and 46 sec…

In a Nested Loops Join, for example, the first accessed table is called the outer table and the second one the inner table. In a Hash Join, the first accessed table is the build input and the second one the probe input. Stream Aggregate and Merge Joi…

advisor调优工具优化sql(基于sql_id) 问题背景:客户反馈数据库迁移后cpu负载激增,帮忙查看原因 解决思路:1> 查看问题系统发现有大量的latch: cache buffers chains 等待:latch:cache buffers chains出现的原因 1.不够优化的SQL. 大量逻辑读的SQL语句就有可能产生非常严重的latch:cache buffers chains等待,因为每次要访问一个block,就需要获得该latch,由于有大量的逻辑读,那么就增加了latc…

Thanks to MS sql could have materialized views ,similar with oracle MVs, using indexed views. what is going on ? are they same thing ? Here we go : (1) general demo tables and rows /****************************************************AboutSQLServer.c…

P6 Professional Installation and Configuration Guide (Microsoft SQL Server Database) 16 R1       May 2016 Contents About This Guide...................................................................................... 11 Shared Topics in This Guide .…

为什么需要SQL Profile Why oracle need SQL Profiles,how it work and what are SQL Profiles... 使用DBMS_XPLAN.DISPLAY分析SQL执行计划,通常会看到Note中有类似下面这样的提示: Note ----- - SQL profile "SYS_SQLPROF_0158283a9b920000" used for this statement SQL profile由人为手工创建或在Automa…

第一章:日志管理 1.forcing log switches sql> alter system switch logfile; 2.forcing checkpoints sql> alter system checkpoint; 3.adding online redo log groups sql> alter database add logfile [group 4]sql> ('/disk3/log4a.rdo','/disk4/log4b.rdo') size 1m…

sql tunning advisor 使用的主要步骤: 1 建立tunning task 2 执行task 3 显示tunning 结果 4 根据建议来运行相应的调优方法  下面来按照这个顺序来实施一遍:    1  建立测试表以及索引 SQL> CREATE TABLE test_sql_advisor AS SELECT OWNER,OBJECT_NAME,OBJECT_ID FROM DBA_OBJECTS; Table created SQL> select count(*) fro…

SQL Server 2012 Introducing Microsoft SQL Server 2012 Microsoft SQL Server 2012 High-Performance T-SQL Using Window Functions Microsoft SQL Server 2012 Pocket Consultant Microsoft SQL Server 2012 A Beginners Guide 5/E (Beginner's Guides) Applied Micr…

This artical is forcused on Oracle 11g Release 2.  It is an summary from the OCP documentation. The topics discussed here including tunning memory, tunning sql, tunning segment access, identifing objects that are invalid or unusable and using Databas…