SQL Statement Tuning

The Need for Tuning

The need for tuning, a simple example SELECT MPRN FROM TLM_CONSUMERS WHERE ZGC = 21991022 .This statement looks quite simple.But, It is a real complex statement, multiple sorts, table scans, complex inner and outer joins. Click on the above link to read more and to become a Oracle DBA.

The Basic Forms of Oracle Data Retrieval

The following sections attempt to explain the various manners in which Oracle will read and work with the data available in order to satisfy your queries. Click on the above link to read more and to become a Oracle DBA.

Oracle Optimizer

Prior to beginning the actual work to satisfy a query Oracle takes a look around and decides on what it thinks is the best way to perform the query. A table may have a number of indexes, they may be composite, unique, functional etc. Click on the above link to read more and to become a Oracle DBA.

Obtaining the Access Plan for a Statement

There are many tools available to help you tune your SQL. Some tools are aimed at DBA's to monitor the server, some at developers to help tune their statements. I have always preferred the standard explain plan for tuning my statements. Click on the above link to read more and to become a Oracle DBA.

Tuning A Single Statement

There are no hard and fast rules to statement tuning. Poor performance can be caused by any number of things, or any combination of a number of things. Each statement is unique, and unique in the context of the instance or schema it is running on. Click on the above link to read more and to become a Oracle DBA.

Identifying Existing Statements

Some DBA's will occassionally look at the code that is currently running on their instances, either out of curiosity (some say it's devil like desire to come and slap us developers about a bit!). Click on the above link to read more and to become a Oracle DBA.

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