Top-n query tuning in huge OLTP applications | Oracle FAQ
Submitted by Marcin Miller on Wed, 2006-02-01 18:00 Top-n Query is one of the more advanced SQL problems. How does one retrieve N first (or least) rows from a record set? For example, how does one find the top five highest-paid employees in a given department? People with no experience in such situation usually try to solve the problem with a query like this: SELECT e.* FROM emp e WHERE ROWNUM < 6
Materialized View Fast Refreshes are Slow | Oracle FAQ
A materialized view that is verified to be fast refresh should update relatively fast. But, what happens when there are few changes to the master table, no network issues, no aggregation in the snapshot query and the refresh still runs slow? About Materialized Views One of the most useful replication and data warehousing features in Oracle is materialized views. Materialized views, also known as s
10gR2 New Feature: Asynchronous Commit | Oracle FAQ
Submitted by Natalka Roshak on Sun, 2005-10-09 19:00 One of the primary tests for DBMS reliability is what's known as the ACID test. ACID-compliant systems are as close as you can get to guaranteed not to lose your data. Essentially, as long as your database files are intact, you are guaranteed that your data is consistent. This is not true for non-ACID compliant systems. Non-ACID-compliant system
Partitioning in Oracle 11g | Oracle FAQ
Partitioning is one of the most sought after options for data warehousing. Almost all Oracle data warehouses use partitioning to improve the performance of queries and also to ease the day-to-day maintenance complexities. Starting with 11G, more partitioning options have been provided and these should reduce the burden of the DBA to a great extent. This article should be helpful to DBAs and Develo
Interval partitioning - Oracle FAQ
Interval partitioning is a partitioning method introduced in Oracle 11g. This is a helpful addition to range partitioning where Oracle automatically creates a partition when the inserted value exceeds all other partition ranges. The following restrictions apply: You can only specify one partitioning key column, and it must be of NUMBER or DATE type. Interval partitioning is NOT supported for index
Monitoring Open and Cached Cursors | Oracle FAQ
Submitted by Natalka Roshak on Thu, 2005-12-01 23:55 Just about every DBA has had to deal with ora-1000 errors, "Maximum open cursors exceeded." This article will discuss initialization parameters that affect open cursors, the difference between open and cached cursors, closing cursors, and monitoring open and cached cursors. Open cursors Open cursors take up space in the shared pool, in the libra
Oracle database Performance Tuning FAQ - Oracle FAQ
General Oracle database Performance Tuning FAQ. Remember: The best performance comes from the unnecessary work you don't do. Why and when should one tune?[edit] One of the biggest responsibilities of a DBA is to ensure that the Oracle database is tuned properly. The Oracle RDBMS is highly tunable and allows the database to be monitored and adjusted to increase its performance. One should do perfor
OracleFAQ: Script and Code Exchange
Below are some free Oracle Scripts and code examples you can download: You can have your scripts and code examples published here. Just upload them and include them on this page. However, please ensure all code is properly formated. General SQL Scripts[edit] Sample SQL matrix report Lookup Oracle error messages Display Database version, installed options and port string "Who am I" script Select th
Oracle FAQ
The Oracle FAQ is NOT an official Oracle Support site, but rather a get-together of people with jobs in Oracle. In our spare time we come together here to learn about Oracle, share knowledge and try to help others solve their problems. In doing so, this sites puts a wealth of information at the fingertips of Oracle professionals all over the world. You can use our directories and powerful search f
SQL*Plus FAQ - Oracle FAQ
What is SQL*Plus and where does it come from?[edit] SQL*Plus is a command line SQL and PL/SQL language interface and reporting tool that ships with the Oracle Database Client and Server software. It can be used interactively or driven from scripts. SQL*Plus is frequently used by DBAs and Developers to interact with the Oracle database. If you are familiar with other databases, sqlplus is equivalen
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Shared Server -- Part III | Oracle FAQ
OraFAQ Forum: Server Administration » Setting db_keep_cache_size