One of the most important responsibilities of an Oracle Database Administrator or Performance Analyst, when it comes to performance diagnostics, is to determine how users access the database. This article is an attempt to show the different ways one can activate tracing of an Oracle session for performance diagnostics. While the Oracle documentation mentions some of the methods, it doesn't cover them all. This article consolidates many methods of tracing an Oracle session, some of which are well documented, as well as methods that are undocumented and reserved.
Is there any limit to the speed of Oracle? With Oracle announcing a new record one million transactions per minute, many believe that there is nothing that Oracle cannot do.
However, what if we have a requirement for a system that must accept high-volume data loads into a single table:
- 500,000 rows per second
- 50 megabytes per second
Is this possible? Using the right tricks you can make Oracle load data at unbelievable speed. However, special knowledge and tricks are required.
If you write Java Server Pages, this article tries to bring together the pieces you need to know to write 'presentation logic'. This article is about custom tags, how to develop them and how to make maximum use of them. This article is also about tag libraries that come with Struts. What is covered is: what is a tag; what is a 'custom' tag; how you can build one; how they make life easier; and how Struts comes with tag libraries for developers to indulge.
While all SQL tuning professionals advocate tuning each individual SQL statement to reduce logical I/O, there are many cases where you do not have the luxury of tuning each-and-every SQL statement in an application. In these cases, the best you can hope to do is adjust the global optimizer parameters to optimizer as many SQL statements as possible.
by Nidhi Jain
Shared memory and semaphores are two important resources for an Oracle instance on Unix. An instance cannot start if it is unable to allocate what it needs.
Oracle Corporation renamed the latest version of their database management system from Oracle 10i to Oracle10G to illustrate their commitment to Grid computing and the GGG (Great Global Grid). Oracle's Chairman and CEO, Larry Ellison, will release Oracle10G at the OracleWorld conference in San Francisco on the 9th of September 2003.
Oracle Managed Files (OMF), a new feature introduced in Oracle9i, enables the Oracle Server to automatically create and delete database files using standard operating system interfaces. This
feature hugely simplifies the job of the DBA, as the DBA doesn't need to interact with the underlying operating system to create and delete files.
When an Oracle Instance is started, the characteristics of the Instance are established by parameters specified within the initialization parameter file. These initialization parameters are either stored in a PFILE or SPFILE. SPFILEs are available in Oracle 9i and above. All prior releases of Oracle are using PFILEs.
Tables can be reorganized and redefined (evolved) on-line with the DBMS_REDEFINITION package. The process is similar to on-line rebuilds of indexes, in that the original table is left on-line, while a new copy of the table is built. However, an index index-rebuild is a singular operation, while table redefinition is a multi-step process.
When Oracle allocates space to a segment (like a table or index), a group of contiguous free blocks, called an extent, is added to the segment. Metadata regarding extent allocation and unallocated extents are either stored in the data dictionary, or in the tablespace itself. Tablespaces that record extent allocation in the dictionary, are called dictionary managed tablespaces, and tablespaces that record extent allocation in the tablespace header, are called locally managed tablespaces.