Oracle和MySQL - 博客园

DFS lock handle等待事件

摘要： The session waits for the lock handle of a global lock request on the distributed file system (DFS). It is most common in a parallel server situation. SolutionsDuring a period of wait, use the followi... 阅读全文

posted @ 2013-03-19 00:47 Oracle和MySQL 阅读(609) 评论(0) 推荐(0)

提高DBWR进程的吞吐量

摘要： Improve DBWR ThroughputTo improve DBWR's throughput, consider the following: Disk capabilities and setup (stripe size, speed, controllers etc...) Using raw devices instead of File System files -- depe... 阅读全文

posted @ 2013-03-19 00:47 Oracle和MySQL 阅读(307) 评论(0) 推荐(0)

Changing an Init.ora Parameter

摘要： To change an init.ora parameter, follow these steps. Open the file called init.ora. For example, if the database is called oraprod, then the file would be called initoraprod.ora. The file can be in a ... 阅读全文

posted @ 2013-03-19 00:47 Oracle和MySQL 阅读(121) 评论(0) 推荐(0)

PX qref latch等待事件

摘要： Contention caused by communication between parallel query processes. SolutionsDecrease the degree of parallelism for the queriesTune the parallel_execution_message_size parameter (may require larger... 阅读全文

posted @ 2013-03-19 00:47 Oracle和MySQL 阅读(255) 评论(0) 推荐(0)

Reduce the Number of SQL Statements

摘要： Shareable SQL uses bind variables rather than literal values. If an application makes use of literal (unshared) SQL then this can severely limit scalability and throughput. The cost of parsing a new S... 阅读全文

posted @ 2013-03-19 00:47 Oracle和MySQL 阅读(132) 评论(0) 推荐(0)

Round-Trip Time

摘要： Round-trip time when running "select 1 from dual" (includes network time but not connect time) on this database. SolutionIf this is high, contact your network administrator to understand network lat... 阅读全文

posted @ 2013-03-19 00:47 Oracle和MySQL 阅读(240) 评论(0) 推荐(0)

Seconds in wait

摘要： The term "seconds in wait" means the number of seconds that a SQL Statement, Database User, etc. was waiting on an event. It is possible that the total number of "seconds in wait" exceeds the total am... 阅读全文

posted @ 2013-03-19 00:47 Oracle和MySQL 阅读(273) 评论(0) 推荐(0)

Exadata Storage Cell Offloading / Smart Scan

摘要： One of the main new features associated with Exadata systems is that I/O can be offloaded to storage servers rather than be done on the database server. Each of the storage servers may get a piece of ... 阅读全文

posted @ 2013-03-19 00:47 Oracle和MySQL 阅读(236) 评论(0) 推荐(1)

Automatic Tuning of Undo Retention

摘要： Oracle 10gR2 and higher automatically tunes the undo retention period based on how the undo tablespace is configured. If the undo tablespace is configured with the AUTOEXTEND option, the database dyna... 阅读全文

posted @ 2013-03-19 00:47 Oracle和MySQL 阅读(186) 评论(0) 推荐(0)

block change tracking buffer space

摘要： Wait is related to the sizing / usage of the CTWR dba buffer in the Large Pool memory structure more ... SolutionsProblem: When a session waits on the "Block Change Tracking Buffer" event, it indica... 阅读全文

posted @ 2013-03-19 00:47 Oracle和MySQL 阅读(459) 评论(0) 推荐(0)

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