Boost ERP/CRM Performance by Reorganizing Your Oracle Database: A Proven Reorganization Strategy Donald Bakels

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Clarissa McCarthy
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1 Boost ERP/CRM Performance by Reorganizing Your Oracle Database: A Proven Reorganization Strategy Donald Bakels Challenge: Oracle Space management in large, active, business critical ERP/CRM sites Donald Bakels is Director of Adfontes Software and has 20 years + experience with Oracle He has a long relationship with Quest Software where he worked as a software consultant around the Globe for more than 8 years. He can be reached at d.bakels@adfontessoftware.nl With today s databases growing faster than ever, sometimes hundreds of them in multiple locations, the typical database administrator (DBA) must spend a significant amount of time performing space management and reorganization to achieve optimal performance, capacity, and availability. Achieving these goals in dynamic database environments especially large, active sites running Oracle under SAP R/3, SAP ECC (ERP Central Component) Oracle E-Business, Siebel, Peoplesoft and JDEdwards is challenging. Such ERP environments have high transaction volumes which require large database storage capacity and routine archiving of data. Inefficient storage can lead to poor I/O performance. DBAs need a comprehensive solution that provides both tools for managing individual databases and tools for capacity management. 1

2 Optimal performance means optimal application response time. But response time can degrade due to a number of space management issues. The four primary issues are: Block fragmentation Row chaining Stagnated indexes Data partitioning Block Fragmentation When data is not efficiently packed inside table blocks, the table has block fragmentation. Block fragmentation leads to excessive I/O, which slows query performance and application response time. There are two main causes of underutilized space inside table blocks: the high water mark effect and inappropriate PCTFREE and PCTUSED settings. High Water Mark Effect Every Oracle table contains a pointer called the high water mark, which indicates the point at which the table is filled. Before data is loaded in a table, the table is empty and the high water mark points to the beginning of the table. As data is inserted into the table, the high water mark rises. It can only rise; even if data is deleted, the high water mark does not go down. Inappropriate PCTFREE and PCTUSED Settings The second cause of wasted space is inappropriate PCTFREE and PCTUSED settings. Together, PCTFREE and PCTUSED regulate the amount of free space in a block, allowing it to expand and contract cyclically. Tables that are maintained frequently, especially those that undergo a lot of inserts and deletes (as opposed to updates), will eventually reach a state where the percentage of the block used is just above the 40% PCTUSED mark in most blocks. When a table reaches this state, Oracle must perform a great deal more I/O to access data, especially for index range scans and full table scans. The result is performance degradation. The only way to adjust the PCTFREE and PCTUSED settings is to reorganize the table. Row Chaining The second important issue that affects performance is row chaining. Oracle distinguishes between two types of chained rows: spanned rows and migrated rows: Migrated rows impose a performance penalty on both full table scans and index range scans. To retrieve a migrated row, Oracle first retrieves the original block, which contains only a pointer. It then uses the pointer to retrieve the block that contains the migrated row. Therefore, to access a series of migrated rows, Oracle must perform twice the number of read operations as for unchained rows. 2

3 Stagnated Indexes The third major performance challenge is stagnated indexes indexes that have become large and sparsely populated. This condition can severely degrade the performance of index range scans. It can also waste a substantial amount of disk space. Data Partitioning The final major performance challenge is data partitioning. When objects that are frequently accessed reside in the same datafile, I/O bottlenecks can result. To better distribute I/O requests among various datafiles and disks, it is advisable to place heavily accessed tables in separate tablespaces. Partitioning distributing objects over several tablespaces Range partitions List partitions Hash partitions Composite partitions 3

What if you could: Predict disk space growth needs to plan for hardware expenditures Eliminate unnecessary disk space purchases by reclaiming

needed to create manual scripts that could otherwise result in costly mistakes Quickly resolve issues and identify top databases and

preventive maintenance of Oracle database space issues like Tablespace Maps and Exception reports identify objects that need to be

4 What if you could: Predict disk space growth needs to plan for hardware expenditures Eliminate unnecessary disk space purchases by reclaiming wasted space Prevent or minimize costly unplanned downtime of the database using online or scheduled reorganizations Eliminate the time needed to create manual scripts that could otherwise result in costly mistakes Quickly resolve issues and identify top databases and tablespaces consuming the most space Save time and resources in space capacity planning across any number of Oracle databases Provide preventive maintenance of Oracle database space issues like Tablespace Maps and Exception reports identify objects that need to be reorganized, repaired, partitioned or relocated. Tablespace Map sort on any column Save time and resources in space capacity planning across any number of Oracle databases 4

5 Considerations and questions you can ask yourself: When there are slowdowns what methods do I use to quickly identify the root cause? How often do we experience performance degradations in my applications and databases How frequently do I defragment or reorganize my oracle databases? What kind of downtime do I experience when performing reorganizations and what is the price of 1 hour downtime for my business? How much time (and costs) is my staff and project teams spending to research and resolve space problems? How much disk space and money can be saved with an appropriate space management solution? How do I plan to future disk space needs? What is the value for my business when my database request time will increase significantly? How much disk space and money can be saved with an appropriate space management solution? What is the value for my business having a reliable, stable and proactively managed database storage solution. How do I determine if my disk space is maximized? How fast are all my databases, tablespaces, and datafiles growing? How much space will I need in the future based on current growth trends? 5

6 Conclusions: Database reorganizations are an essential part of good database performance. If your database administrators are dealing with terrabytes of business critical data they need tools to help them. Complement your investment in your ERP/CRM applications by using a state of the art database space management solution and optimize your business critical processes. References: Space Management Community More information: info@adfontessoftware.nl A solid database space management solution has direct ROI, will save costs, improves performance and proactively manages and stabilizes your ERP/CRM Oracle databases which are most likely essential for your business. Quest s Spacemanager with Livereorg has the ability to run reorganizations with no downtime, which is an unique differentiator and is a proven solution where hundreds of companies businesses are relying on. 6

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