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• Cause of degraded application performance • Various questions on Oracle From: Chakersh Katare: Hi, I am facing problem related to performance. I moved all my SQL statements from Client layer to Database layer in the form of Stored Procedures. I was thinking that performance of my Application will be improved but reverse is happening, performance is going down by nearly 30% . Why is it happening can u suggest some valuable ideas so that i can improve performance of my database. We can only guess that there are other factors are the cause of this loss of performance such as more users, or adding/dropping indexes. Our suggestions would be make sure you analyse tables and indexes to give the optimiser accurate statistics. Pin the most frequently used packages into memory. Query the database to find out which queries are taking the most time or use the most i/o and then set about optimising them. Also make sure the Oracle server has enough real (physcial) memory on the machine where it is running. If PL/SQL code has been taken from the client and put on the server the overall memory requirements may well have increased. You will need to look at the performance statistics at the operating system level to determine this. Look for processes being swapped out of memory and/or very high memory utilisation. Disk access is the slowest operation and swapping processes in and out of memory will cause very poor performance. For more help with Oracle performance tuning see the many free articles and tutorials we have on our site or consider taking some of our formal Oracle training courses. The Oracle resources page has book recommendations as well as links to OTN and other useful sites. --------- From Saritha V: I would appreciate if u could answer these questions and provide me with links and resources where i could find info. 1. What are different types of cursors? 2. What cursor type do you use to retrieve multiple recordsets? 3. What are different types of index? 4. which type of index does the oracle create when we define primary key? 5. what are tradeoffs having index? 6. What is the diference between "NULL in C" and "NULL in Oracle?" 7. What are "HINTS"? What is "index covering" of a query? That's a lot of questions and to answer them fully would require half a book at least. We would recommend that you read some of the books recommended on the Oracle resources page. Meanwhile here are some brief answers.    1. There are implicit and explicit cursors for queries, updates and deletes    2. If you're using PL/SQL you need to declare an explicit cursor to retrieve multiple records    3. There are two main types of index: unique and non-unique, there also bit-map indexes and b-tree indexes which describe the physical structure of the indexes.    4. A primary key index is always unique - also columns in the primary key may not be null    5. The trade-offs to consider when using indexes is that whilst read operations are quicker (hopefully), insert update and delete operations are slower because of the need to maintain the index(es) in line with the data.    6. NULL in Oracle means the value is undefined    7. Hints are just instructions that the Oracle optimiser will try to use to perform the required operation. See the many free articles and tutorials we have on our site for more help or consider taking some of our formal Oracle training courses.  --------------------------------------- Looking to sky-rocket productivity, save time and reduce costs? Training is a highly cost-effective and proven method of boosting productivity.  Smartsoft offers instructor-led training in Oracle and related technologies on or off site in cities across the UK as well as self-study online training. See our scheduled Oracle training courses, or let us know your requirements. Oracle tips and tricks Subscribe to our newsletter, jam-packed full of tips and tricks to help you slash costs, sky-rocket productivity and make your systems better, faster and smarter. © Smartsoft Computing Ltd, Bristol, England Need help? Contact Us This site uses woopra.com to gather statistical information about our visitors. This data is aggregated to show industry trends (such as browser share). However, this data shall be the average of many thousands of visits and is in no way linked to individuals. View woopra privacy policy.     View Smartsoft privacy policy Oracle and Java are registered trademarks of Oracle and/or its affiliates. Other names may be trademarks of their respective owners.