Database Journal
MS SQL Oracle DB2 Access MySQL PostgreSQL Sybase PHP SQL Etc SQL Scripts & Samples Links Database Forum

» Database Journal Home
» Database Articles
» Database Tutorials
MS SQL
Oracle
DB2
MS Access
MySQL
» RESOURCES
Database Tools
SQL Scripts & Samples
Links
» Database Forum
» Sitemap
Free Newsletters:
DatabaseDaily  
News Via RSS Feed


follow us on Twitter
Database Journal |DBA Support |SQLCourse |SQLCourse2
 

Featured Database Articles

Database News

Posted Dec 12, 2003

Database administration: Causes of Oracle buffer busy waits

By DatabaseJournal.com Staff

[From Builder.com]

One of the most confounding problems with Oracle is the resolution of buffer busy wait events. Buffer busy waits are common in an I/O-bound Oracle system, as evidenced by any system with read (sequential/scattered) waits in the top-five waits in the Oracle STATSPACK report, like this:

Top 5 Timed Events
                                                         % Total
Event                         Waits        Time (s)     Ela Time
--------------------------- ------------ ----------- -----------
db file sequential read       2,598        7,146           48.54
db file scattered read       25,519        3,246           22.04
library cache load lock         673        1,363            9.26
CPU time                      2,154          934            7.83
log file parallel write      19,157          837            5.68
 

The main way to reduce buffer busy waits is to reduce the total I/O on the system. This can be done by tuning the SQL to access rows with fewer block reads (i.e., by adding indexes). Even if we have a huge db_cache_size, we may still see buffer busy waits, and increasing the buffer size won't help.

The article continues at http://builder.com.com/5100-6388-5110875.html?tag=sc



Database News Archives

Comment and Contribute

 


(Maximum characters: 1200). You have characters left.

 

 




Latest Forum Threads
Database News Forum
Topic By Replies Updated
Efficient SQL Server Indexing by Design lcole 0 April 30th, 12:38 PM
Mine Oracle Database, SQL Server and Other Databases with Monarch Data Pump Pro V10.5 lcole 0 April 30th, 12:37 PM
Oracle Database and Oracle Fusion Middleware for Private Social Network Application lcole 0 April 30th, 12:31 PM
Oracle Database Maintains a Stronghold in the DBMS Market lcole 0 April 30th, 12:30 PM


















Thanks for your registration, follow us on our social networks to keep up-to-date