RE: How to understand SGA?

I have a generic but IMO important advice for you.

When dealing with questions like the following...

> So what is the meaning of "server processes" here? Which definition is more accurate? How to understand SGA?

... the first thing you should do is to open the Concept Guide at http://docs.oracle.com/database/121/CNCPT/toc.htm. For example, in this specific case, "Overview of the System Global Area (SGA)" at http://docs.oracle.com/database/121/CNCPT/memory.htm#GUID-24EDB8CD-8279-4CED-82AF-642FC01A4A73. In there you also find the term "server processes"... so, if you don't know what those things are, you check the Glossary available in the same book. So, for "server processes", you find a definition at http://docs.oracle.com/database/121/CNCPT/glossary.htm#GUID-E660AC1C-B704-4DC1-A35A-DB49EFB34F4A.

The Concept Guide is one of the most important books published by Oracle. Every time you have question related to the architecture of the database engine, you should refer to it.

HTH
Chris Antognini

Troubleshooting Oracle Performance, Apress 2008/2014 http://top.antognini.ch

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